U.S. patent application number 10/224903 was filed with the patent office on 2003-08-07 for single dose azithromycin.
Invention is credited to Dunne, Michael William.
Application Number | 20030148964 10/224903 |
Document ID | / |
Family ID | 23217490 |
Filed Date | 2003-08-07 |
United States Patent
Application |
20030148964 |
Kind Code |
A1 |
Dunne, Michael William |
August 7, 2003 |
Single dose azithromycin
Abstract
The present invention relates to a method of treating infections
in humans by administering a single dose of azithromycin.
Inventors: |
Dunne, Michael William; (Old
Saybrook, CT) |
Correspondence
Address: |
Connolly Bove Lodge & Hutz LLP
1220 Market Street
P.O. Box 2207
Wilmington
DE
19899
US
|
Family ID: |
23217490 |
Appl. No.: |
10/224903 |
Filed: |
August 21, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60313867 |
Aug 21, 2001 |
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Current U.S.
Class: |
514/28 |
Current CPC
Class: |
A61P 27/16 20180101;
A61K 31/7052 20130101; A61P 31/04 20180101; A61P 11/00
20180101 |
Class at
Publication: |
514/28 |
International
Class: |
A61K 031/7052 |
Claims
1. A method of treating a respiratory infection in a human
comprising administering to a human in need thereof a single dose
of azithromycin wherein the dose is about 30 mg/kg body weight or
greater.
2. The method of claim 1 wherein the dose is about 31 mg/kg body
weight or greater.
3. The method of claim 1 wherein the dose is about 50 mg/kg body
weight or greater.
4. The method of claim 1 wherein the dose is about 70 mg/kg body
weight or greater.
5. The method of claim 1 wherein the dose is between about 30 mg/kg
and 90 mg/kg body weight.
6. The method of claim 1 wherein the dose is between about 30 mg/kg
and 35 mg/kg body weight.
7. The method of claim 1 wherein the dose is between about 31 mg/kg
and 35 mg/kg body weight.
8. The method of claim 1 wherein the dose is between about 35 mg/kg
and 40 mg/kg body weight.
9. The method of claim 1 wherein the dose is between about 40 mg/kg
and 45 mg/kg body weight.
10. The method of claim 1 wherein the dose is between about 45
mg/kg and 50 mg/kg body weight.
11. The method of claim 1 wherein the dose is between about 50
mg/kg and 55 mg/kg body weight.
12. The method of claim 1 wherein the dose is between about 55
mg/kg and 60 mg/kg body weight.
13. The method of claim 1 wherein the dose is between about 60
mg/kg and 65 mg/kg body weight.
14. The method of claim 1 wherein the dose is between about 65
mg/kg and 70 mg/kg body weight.
15. The method of claim 1 wherein the dose is between about 70
mg/kg and 75 mg/kg body weight.
16. The method of claim 1 wherein the dose is between about 75
mg/kg and 80 mg/kg body weight.
17. The method of claim 1 wherein the dose is between about 80
mg/kg and 85 mg/kg body weight.
18. The method of claim 1 wherein the dose is between about 85
mg/kg and 90 mg/kg body weight.
19. The method of claim 1 wherein the human is an adult sixteen
years of age or older.
20. The method of claim 1 wherein the respiratory infection is
acute otitis media.
21. A method of treating a respiratory infection in a human
comprising administering to a human in need thereof a single dose
of azithromycin wherein the dose is within the range of about 0.15
to 4.5 g.
22. The method of claim 21 wherein the respiratory infection is
acute otitis media.
23. The method of claim 21 wherein the dose is within the range of
about 0.15 to 1.5 g.
24. The method of claim 21 wherein the dose is within the range of
about 1.5 to 2.5 g.
25. The method of claim 21 wherein the dose is within the range of
about 2.5 to 3.5 g.
26. The method of claim 21 wherein the dose is within the range of
about 3.5 to 4.5 g.
27. The method of claim 21 wherein the human is an adult sixteen
years of age or older.
28. A method of treating a respiratory infection caused by S.
pneumoniae in a human comprising administering to a human in need
thereof a single dose of azithromycin wherein the dose is about 30
mg/kg body weight or greater.
29. The method of claim 28 wherein the human is an adult sixteen
years of age or older.
30. The method of claim 28 wherein the respiratory infection is
acute otitis media.
31. The method of claim 28 wherein the dose is about 31 mg/kg body
weight or greater.
32. The method of claim 28 wherein the dose is about 50 mg/kg body
weight or greater.
33. The method of claim 28 wherein the dose is about 70 mg/kg body
weight or greater.
34. The method of claim 28 wherein the dose is between about 30
mg/kg and 90 mg/kg body weight.
35. The method of claim 28 wherein the dose is between about 30
mg/kg and 35 mg/kg body weight.
36. The method of claim 28 wherein the dose is between about 31
mg/kg and 35 mg/kg body weight.
37. The method of claim 28 wherein the dose is between about 35
mg/kg and 40 mg/kg body weight.
38. The method of claim 28 wherein the dose is between about 40
mg/kg and 45 mg/kg body weight.
39. The method of claim 28 wherein the dose is between about 45
mg/kg and 50 mg/kg body weight.
40. The method of claim 28 wherein the dose is between about 50
mg/kg and 55 mg/kg body weight.
41. The method of claim 28 wherein the dose is between about 55
mg/kg and 60 mg/kg body weight.
42. The method of claim 28 wherein the dose is between about 60
mg/kg and 65 mg/kg body weight.
43. The method of claim 28 wherein the dose is between about 65
mg/kg and 70 mg/kg body weight.
44. The method of claim 28 wherein the dose is between about 70
mg/kg and 75 mg/kg body weight.
45. The method of claim 28 wherein the dose is between about 75
mg/kg and 80 mg/kg body weight.
46. The method of claim 28 wherein the dose is between about 80
mg/kg and 85 mg/kg body weight.
47. The method of claim 28 wherein the dose is between about 85
mg/kg and 90 mg/kg body weight.
48. The method of claim 28 wherein the respiratory infection is
caused by an S. pneumoniae isolate containing a mef A gene.
49. The method of claim 48 wherein the human is an adult sixteen
years of age or older.
50. The method of claim 48 wherein the respiratory infection is
acute otitis media.
51. The method of claim 48 wherein the dose is about 31 mg/kg body
weight or greater.
52. The method of claim 48 wherein the dose is about 50 mg/kg body
weight or greater.
53. The method of claim 48 wherein the dose is about 70 mg/kg body
weight or greater.
54. The method of claim 48 wherein the dose is between about 30
mg/kg and 90 mg/kg body weight.
55. The method of claim 48 wherein the dose is between about 30
mg/kg and 35 mg/kg body weight.
56. The method of claim 48 wherein the dose is between about 31
mg/kg and 35 mg/kg body weight.
57. The method of claim 48 wherein the dose is between about 35
mg/kg and 40 mg/kg body weight.
58. The method of claim 48 wherein the dose is between about 40
mg/kg and 45 mg/kg body weight.
59. The method of claim 48 wherein the dose is between about 45
mg/kg and 50 mg/kg body weight.
60. The method of claim 48 wherein the dose is between about 50
mg/kg and 55 mg/kg body weight.
61. The method of claim 48 wherein the dose is between about 55
mg/kg and 60 mg/kg body weight.
62. The method of claim 48 wherein the dose is between about 60
mg/kg and 65 mg/kg body weight.
63. The method of claim 48 wherein the dose is between about 65
mg/kg and 70 mg/kg body weight.
64. The method of claim 48 wherein the dose is between about 70
mg/kg and 75 mg/kg body weight.
65. The method of claim 48 wherein the dose is between about 75
mg/kg and 80 mg/kg body weight.
66. The method of claim 48 wherein the dose is between about 80
mg/kg and 85 mg/kg body weight.
67. The method of claim 48 wherein the dose is between about 85
mg/kg and 90 mg/kg body weight.
68. A method of treating a respiratory infection caused by H.
influenzae in a human comprising administering to a human in need
thereof a single dose of azithromycin wherein the dose is about 30
mg/kg body weight or greater.
69. The method of claim 68 wherein the human is an adult sixteen
years of age or older.
70. The method of claim 68 wherein the respiratory infection is
acute otitis media.
71. The method of claim 68 wherein the dose is about 31 mg/kg body
weight or greater.
72. The method of claim 68 wherein the dose is about 50 mg/kg body
weight or greater.
73. The method of claim 68 wherein the dose is about 70 mg/kg body
weight or greater.
74. The method of claim 68 wherein the dose is between about 30
mg/kg and 90 mg/kg body weight.
75. The method of claim 68 wherein the dose is between about 30
mg/kg and 35 mg/kg body weight.
76. The method of claim 68 wherein the dose is between about 31
mg/kg and 35 mg/kg body weight.
77. The method of claim 68 wherein the dose is between about 35
mg/kg and 40 mg/kg body weight.
78. The method of claim 68 wherein the dose is between about 40
mg/kg and 45 mg/kg body weight.
79. The method of claim 68 wherein the dose is between about 45
mg/kg and 50 mg/kg body weight.
80. The method of claim 68 wherein the dose is between about 50
mg/kg and 55 mg/kg body weight.
81. The method of claim 68 wherein the dose is between about 55
mg/kg and 60 mg/kg body weight.
82. The method of claim 68 wherein the dose is between about 60
mg/kg and 65 mg/kg body weight.
83. The method of claim 68 wherein the dose is between about 65
mg/kg and 70 mg/kg body weight.
84. The method of claim 68 wherein the dose is between about 70
mg/kg and 75 mg/kg body weight.
85. The method of claim 68 wherein the dose is between about 75
mg/kg and 80 mg/kg body weight.
86. The method of claim 68 wherein the dose is between about 80
mg/kg and 85 mg/kg body weight.
87. The method of claim 68 wherein the dose is between about 85
mg/kg and 90 mg/kg body weight.
88. A method of treating an infection caused by S. pyogenes in a
human comprising administering to a human in need thereof a single
dose of azithromycin wherein the dose is about 30 mg/kg body weight
or greater.
89. The method of claim 88 wherein the human is an adult sixteen
years of age or older.
90. The method of claim 88 wherein the infection is a respiratory
infection.
91. The method of claim 88 wherein the dose is about 31 mg/kg body
weight or greater.
92. The method of claim 88 wherein the dose is about 50 mg/kg body
weight or greater.
93. The method of claim 88 wherein the dose is about 70 mg/kg body
weight or greater.
94. The method of claim 88 wherein the dose is between about 30
mg/kg and 90 mg/kg body weight.
95. The method of claim 88 wherein the dose is between about 30
mg/kg and 35 mg/kg body weight.
96. The method of claim 88 wherein the dose is between about 31
mg/kg and 35 mg/kg body weight.
97. The method of claim 88 wherein the dose is between about 35
mg/kg and 40 mg/kg body weight.
98. The method of claim 88 wherein the dose is between about 40
mg/kg and 45 mg/kg body weight.
99. The method of claim 88 wherein the dose is between about 45
mg/kg and 50 mg/kg body weight.
100. The method of claim 88 wherein the dose is between about 50
mg/kg and 55 mg/kg body weight.
101. The method of claim 88 wherein the dose is between about 55
mg/kg and 60 mg/kg body weight.
102. The method of claim 88 wherein the dose is between about 60
mg/kg and 65 mg/kg body weight.
103. The method of claim 88 wherein the dose is between about 65
mg/kg and 70 mg/kg body weight.
104. The method of claim 88 wherein the dose is between about 70
mg/kg and 75 mg/kg body weight.
105. The method of claim 88 wherein the dose is between about 75
mg/kg and 80 mg/kg body weight.
106. The method of claim 88 wherein the dose is between about 80
mg/kg and 85 mg/kg body weight.
107. The method of claim 88 wherein the dose is between about 85
mg/kg and 90 mg/kg body weight.
108. A method of treating an infection caused by E. faecalis in a
human comprising administering to a human in need thereof a single
dose of azithromycin wherein the dose is about 30 mg/kg body weight
or greater.
109. The method of claim 108 wherein the human is an adult sixteen
years of age or older.
110. The method of claim 108 wherein the infection is a urinary
tract infection.
111. The method of claim 108 wherein the dose is about 31 mg/kg
body weight or greater.
112. The method of claim 108 wherein the dose is about 50 mg/kg
body weight or greater.
113. The method of claim 108 wherein the dose is about 70 mg/kg
body weight or greater.
114. The method of claim 108 wherein the dose is between about 30
mg/kg and 90 mg/kg body weight.
115. The method of claim 108 wherein the dose is between about 30
mg/kg and 35 mg/kg body weight.
116. The method of claim 108 wherein the dose is between about 31
mg/kg and 35 mg/kg body weight.
117. The method of claim 108 wherein the dose is between about 35
mg/kg and 40 mg/kg body weight.
118. The method of claim 108 wherein the dose is between about 40
mg/kg and 45 mg/kg body weight.
119. The method of claim 108 wherein the dose is between about 45
mg/kg and 50 mg/kg body weight.
120. The method of claim 108 wherein the dose is between about 50
mg/kg and 55 mg/kg body weight.
121. The method of claim 108 wherein the dose is between about 55
mg/kg and 60 mg/kg body weight.
122. The method of claim 108 wherein the dose is between about 60
mg/kg and 65 mg/kg body weight.
123. The method of claim 108 wherein the dose is between about 65
mg/kg and 70 mg/kg body weight.
124. The method of claim 108 wherein the dose is between about 70
mg/kg and 75 mg/kg body weight.
125. The method of claim 108 wherein the dose is between about 75
mg/kg and 80 mg/kg body weight.
126. The method of claim 108 wherein the dose is between about 80
mg/kg and 85 mg/kg body weight.
127. The method of claim 108 wherein the dose is between about 85
mg/kg and 90 mg/kg body weight.
128. A method of treating a respiratory infection caused by M.
catarrhalis in a human comprising administering to a human in need
thereof a single dose of azithromycin wherein the dose is about 30
mg/kg body weight or greater.
129. The method of claim 128 wherein the human is an adult sixteen
years of age or older.
130. The method of claim 128 wherein the respiratory infection is
acute otitis media.
131. The method of claim 128 wherein the dose is about 31 mg/kg
body weight or greater.
132. The method of claim 128 wherein the dose is about 50 mg/kg
body weight or greater.
133. The method of claim 128 wherein the dose is about 70 mg/kg
body weight or greater.
134. The method of claim 128 wherein the dose is between about 30
mg/kg and 90 mg/kg body weight.
135. The method of claim 128 wherein the dose is between about 30
mg/kg and 35 mg/kg body weight.
136. The method of claim 128 wherein the dose is between about 31
mg/kg and 35 mg/kg body weight.
137. The method of claim 128 wherein the dose is between about 35
mg/kg and 40 mg/kg body weight.
138. The method of claim 128 wherein the dose is between about 40
mg/kg and 45 mg/kg body weight.
139. The method of claim 128 wherein the dose is between about 45
mg/kg and 50 mg/kg body weight.
140. The method of claim 128 wherein the dose is between about 50
mg/kg and 55 mg/kg body weight.
141. The method of claim 128 wherein the dose is between about 55
mg/kg and 60 mg/kg body weight.
142. The method of claim 128 wherein the dose is between about 60
mg/kg and 65 mg/kg body weight.
143. The method of claim 128 wherein the dose is between about 65
mg/kg and 70 mg/kg body weight.
144. The method of claim 128 wherein the dose is between about 70
mg/kg and 75 mg/kg body weight.
145. The method of claim 128 wherein the dose is between about 75
mg/kg and 80 mg/kg body weight.
146. The method of claim 128 wherein the dose is between about 80
mg/kg and 85 mg/kg body weight.
147. The method of claim 128 wherein the dose is between about 85
mg/kg and 90 mg/kg body weight.
Description
[0001] This application is a continuation-in-part of U.S. Patent
Application 60/313,867, filed Aug. 21, 2001, which is hereby
incorporated by reference herein in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to a method of treating
infection by administering a single dosage of azithromycin.
BACKGROUND OF THE INVENTION
[0003] Azithromycin is the U.S.A.N. (generic name) for
9a-aza-9a-methyl-9-deoxo-9a-homoerythromycin A, a broad spectrum
antimicrobial compound derived from erythromycin A. Azithromycin
was independently discovered by Bright, U.S. Pat. No. 4,474,768 and
Kobrehel et al., U.S. Pat. No. 4,517,359. These patents disclose
that azithromycin and certain derivatives thereof possess
antibacterial properties and are accordingly useful as antibiotics.
Azithromycin may be made, formulated and administered according to
procedures described in the following US patents, which are all
incorporated herein in their entirety by reference: U.S. Pat. Nos.
6,268,489; 4,963,531; 5,633,006; 5,686,587; 5,605,889; 6,068,859;
4,328,334; and 5,498,699.
[0004] Azithromycin is administered for the treatment of
infections, particularly respiratory infections, more particularly
respiratory infections of the bronchial tract, lungs, and sinus,
and still more particularly acute otitis media. Acute otitis media
is an inflammation of the area behind the eardrum (tympanic
membrane) in the chamber called the middle ear. Acute otitis media
is an infection that produces pus, fluid, and inflammation within
the middle ear.
[0005] Acute otitis media may be caused by a variety of pathogens,
such as M. catarrhalis, S. pneumoniae, and H. influenzae. Acute
otitis media is particularly common in infants and children.
Azithromycin has been prescribed for the treatment of acute otitis
media with a 30 mg/kg body weight total treatment dose given as a
five day regimen in the US and as a three day regimen in Europe.
The multiple dosages prescribed to completely cure the infection
have caused compliance problems, particularly in pediatric
patients. Even in the adult population, compliance with multiple
dosaging regimens is not complete because of forgetfulness and
other reasons. A method of treating and curing infection,
particularly a microbial infection such as acute otitis media, by
administering a single dose of azithromycin would significantly
shorten courses of therapy and be of a great advantage to patient
compliance.
[0006] A continual problem with antibiotic therapy is the emergence
of resistant microbial strains. A method of treating microbial
infections with a reduced risk of developing treatment-resistant
strains is desirable. It is believed that a single dose
azithromycin treatment provides such as reduced risk. The
inflammatory cells provide a mode of transport of azithromycin to
the infection site and provide a reservoir for azithromycin at the
infection site. As a result, azithromycin is characterized by high
and sustained concentrations in a wide range of tissues, and a
particularly increased concentration at sites of infection. It is
believed that a single dose therapy with azithromycin, by providing
a higher initial concentration at the infection site, may help
prevent less susceptible sub-populations of the pathogens initially
present from becoming established. Also, a single-dose regimen will
result in greater patient compliance, which should contribute to
reduced emergence of less susceptible strains.
[0007] A related resistance problem is the problem of treating
infection caused by pathogens having a high susceptibility
threshold to most therapeutically available antiinfective agents.
Such resistant pathogens are characterized by being unlikely to be
inhibited if the antimicrobial compound reaches the concentrations
usually achievable and other therapy is needed. Often, the other
therapy involves anti-infective agents with undesirable side
effects, such as severe gastrointestinal distress or heightened
sensitivity to sun. It is an ongoing problem to develop new
therapies to treat disorders caused by such pathogens that exhibit
resistance to available anti-infective agents while minimizing
undesirable side-effects. It is an object of the present invention
to solve these problems with a well-tolerated therapy of a
sufficient dosage of azithromycin administered as a single dose to
treat infections caused by certain resistant pathogens.
[0008] Single dose administration of azithromycin for the treatment
of non-gonococcal urethritis and cervicitis due to C. trachomatis
has been prescribed and is a therapy approved by the US Food and
Drug Administration. Single dose treatment of respiratory
infections in humans with azithromycin has been reported. For
example, Stan Block et al. reported on a study in which a single
dose of azithromycin (30 mg/kg) was administered to treat acute
otitis media in infants and children six months to twelve years of
age. S. Block et al., "Single-Dose Azithromycin (30 mg/kg) in Acute
Otitis Media", 38.sup.th Annual Meeting of the Infectious Diseases
Society of America, New Orleans LA, Sept. 7-10, 2000 [Abstract
174]. Arguedas reported on single-dose therapy in otitis media
using azithromycin in infants and children. Arguedas, A.,
"Single-dose therapy in otitis media", Poster Presentation at
9.sup.th European Congress of Clinical Microbiology and Infectious
Diseases, Berlin, Germany, Mar. 21-24, 1999, Clin. Microbiol.
Infect. 1999:5 (Supp. 3 March):28 (Abstr). A single oral dose of 2
g azithromycin was administered to healthy male subjects in tests
of gastrointestinal side effects reported in U.S. Pat. No.
6,068,859.
SUMMARY OF THE INVENTION
[0009] The present invention provides a method of treating a
respiratory infection in a human comprising administering to a
human in need thereof a single dose of azithromycin wherein the
dose is about 30 mg/kg body weight or greater. In another
embodiment, the invention is directed to a method of treating a
respiratory infection in a human comprising administering to a
human in need thereof a single dose of azithromycin wherein the
dose is within the range of about 0.15 to 4.5 g.
[0010] A further embodiment is directed to a method of treating a
respiratory infection caused by S. pneumoniae isolates in a human
comprising administering to a human in need thereof a single dose
of azithromycin. A further embodiment involves the treatment of a
respiratory infection in a human in which the respiratory infection
is caused by an S. pneumoniae isolate containing a mef A gene. In
yet another embodiment, the invention is directed to a method of
treating a respiratory infection caused by H. influenzae in a human
comprising administering to a human in need thereof a single dose
of azithromycin. A further embodiment is directed to a method of
treating an infection caused by S. pyogenes in a human comprising
administering to a human in need thereof a single dose of
azithromycin. In a still further embodiment, the invention is
directed to a method of treating an infection caused by E. faecalis
in a human comprising administering to a human in need thereof a
single dose of azithromycin. The invention is also directed to a
method of treating a respiratory infection caused by M. catarrhalis
in a human comprising administering to a human in need thereof a
single dose of azithromycin.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 shows Day 28 Outcome and MIC Distribution for
azithromycin. Baseline susceptibility data for azithromycin was
available for 66 subjects with S. pneumonia who had a clinical
outcome on day 28. Clinical cure is shown in gray and clinical
failures in black. Isolates with an MIC of 8 .mu.l/ml to
azithromycin contained the mef A gene and isolates with an
MIC>256 .mu.l/mi contained the erm B gene.
[0012] FIG. 2 shows H. influenzae Clinical Outcome--Test of Cure
Visit day 21-35. Presented are the 95% confidence intervals on the
point estimate of success for all drugs approved for treatment of
otitis media that had data available in the product label on
clinical outcome at day 28 in patients with H. influenzae
identified at baseline. The data is presented as clinical success
(cure+improvement) or cure alone as shown in the label. The
vertical dashed lines mark the limits of the 95% confidence
interval for single dose azithromycin. No attempt was made to
adjust outcomes by important demographic variables.
[0013] FIGS. 3a and 3b show the eradication of H. influenzae in a
gerbil model of middle ear infection.
[0014] FIG. 4 shows the impact of different dosage regimens of
Augmentin.RTM. amoxicillin/clavulanate potassium (from
GlaxoSmithKline, Inc.) on an infection of H. influenzae in a gerbil
model of middle ear infection.
[0015] FIG. 5 shows azithromycin mouse serum concentrations
following dosage of azithromycin administered over one, two or
three days.
DETAILED DISCUSSION
[0016] The invention provides a method of treating infections,
particularly respiratory infections such as acute otitis media, in
a human in need thereof by administering a single dose of
azithromycin. The human patient may be an adult sixteen years of
age or older, a child under sixteen years of age, or a young child
twelve years of age or younger. By "single dose" is meant a dosage
that is administered only once over a 28-day period. The dosage may
be administered in a single dosage form, such as one capsule or
tablet, or may be divided, e.g. constituted by more than one dosage
form, such as by multiple capsules or tablets that are taken at or
about the same time. Any type of dosage form may be used, such as
capsule, tablet, liquid suspension for oral administration, or
liquid for intravenous administration.
[0017] The "single dose" of the invention is formulated for
immediate release and is not formulated for controlled, sustained
or delayed release. For example, an orally administered
azithromycin single dose administered according to the present
invention is preferably in a form such that it releases
azithromycin to the human gastrointestinal tract at a rate such
that the total amount of azithromycin released therein is more than
4 mg of azithromycin per kg of patient weight in the first fifteen
minutes after ingestion and more preferably is more than 30 mg of
azithromycin per kg of weight in the first six hours after
ingestion.
[0018] Azithromycin can be employed in its pharmaceutically
acceptable salts and also in anhydrous as well as hydrated forms,
such as the di- and mono-hydrates. All such forms are within the
scope of this invention. The azithromycin employed is preferably
the dihydrate, which is disclosed in published European Patent
Application 0 298 650 A2.
[0019] Under the inventive methods, respiratory infections in
humans are treated by administering azithromycin in a single dose
of about 30 mg/kg body weight or greater.
[0020] Preferably, the single dose is between about 30 mg/kg and 90
mg/kg. Other preferred dosages are between about 30 mg/kg and 35
mg/kg body weight, between about 31 mg/kg and 35 mg/kg body weight,
between about 35 mg/kg and 40 mg/kg body weight, between about 40
mg/kg and 45 mg/kg body weight, between about 45 mg/kg and 50 mg/kg
body weight, between about 50 mg/kg and 55 mg/kg body weight,
between about 55 mg/kg and 60 mg/kg body weight, between about 60
mg/kg and 65 mg/kg body weight, between about 65 mg/kg and 70 mg/kg
body weight, between about 70 mg/kg and 75 mg/kg body weight,
between about 75 mg/kg and 80 mg/kg body weight, between about 80
mg/kg and 85 mg/kg body weight, and between about 85 mg/kg and 90
mg/kg body weight.
[0021] Other preferred doses are the following doses: 31 mg/kg or
greater, 32 mg/kg or greater, 33 mg/kg or greater, 34 mg/kg or
greater, 35 mg/kg or greater, 36 mg/kg or greater, 37 mg/kg or
greater, 38 mg/kg or greater, 39 mg/kg or greater, 40 mg/kg or
greater, 41 mg/kg or greater, 42 mg/kg or greater, 43 mg/kg or
greater, 44 mg/kg or greater, 45 mg/kg or greater, 46 mg/kg or
greater, 47 mg/kg or greater, 48 mg/kg or greater, 49 mg/kg or
greater, 50 mg/kg or greater, 51 mg/kg or greater, 52 mg/kg or
greater, 53 mg/kg or greater, 54 mg/kg or greater, 55 mg/kg or
greater, 56 mg/kg or greater, 57 mg/kg or greater, 58 mg/kg or
greater, 59 mg/kg or greater, 60 mg/kg or greater, 61 mg/kg or
greater, 62 mg/kg or greater, 63 mg/kg or greater, 64 mg/kg or
greater, 65 mg/kg or greater, 66 mg/kg or greater, 67 mg/kg or
greater, 68 mg/kg or greater, 69 mg/kg or greater, 70 mg/kg or
greater, 71 mg/kg or greater, 72 mg/kg or greater, 73 mg/kg or
greater, 74 mg/kg or greater, 75 mg/kg or greater, 76 mg/kg or
greater, 77 mg/kg or greater, 78 mg/kg or greater, 79 mg/kg or
greater, 80 mg/kg or greater, 81 mg/kg or greater, 82 mg/kg or
greater, 83 mg/kg or greater, 84 mg/kg or greater, 85 mg/kg or
greater, 86 mg/kg or greater, 87 mg/kg or greater, 88 mg/kg or
greater, 89 mg/kg or greater, and about 90 mg/kg.
[0022] In another embodiment, the single dose of azithromycin is
administered as a single dose within the range of about 0.15 to 4.5
g, preferably a dose within the range of about 0.15 to 1.5 g or
about 1.5 to 4.5 g. Other preferred doses are a single dose within
the range of about 0.7 to 1.5 g, a single dose within the range of
about 1.5 to 2.5 g, a single dose within the range of about 2.5 to
3.5 g, and a single dose within the range of about 3.5 to 4.5 g. In
other embodiments, the single dose is selected from the group
consisting of 0.15, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0,
1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3,
2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6,
3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, and 4.5 g.
[0023] The methods of the invention may be used to treat infections
caused or mediated by different pathogens. Preferably, the pathogen
is selected from S. aureaus, S. pneumoniae, H. influenzae, M.
catarrhalis, E. faecalis, and S. pyrogenes, and more preferably is
selected from S. pneumoniae isolates having a mef A gene, H.
influenzae and M. catarrhalis. The invention preferably is directed
to treating a respiratory infection such as acute otitis media
caused or mediated in whole or part by one of these specified
pathogens.
EXAMPLES
[0024] 1.0 Single Dose Azithromycin Pediatric Test
[0025] Azithromycin has a long half-life in infected tissues. On
pharmocokinetic grounds, it is not the duration but rather the
total dose of azithromycin that is predicted to correlate most
closely with clinical efficacy. Craig, W. A., "Postantibiotic
effects and the dosing of Macrolides, azalides, and
streptogramins", In: Zinner, S. H. et al. (editor) Expanding
Indications for New Macrolides, Azalides, and Streptogramins, New
York: Marel Dekker (1997), pp.27-38. A study was undertaken to
examine the efficacy of a single 30 mg/kg oral dose of azithromycin
in the treatment of acute otitis media in children.
[0026] A trial was performed using a single 30-mg/kg dose of
azithromycin in the treatment of otitis media in pediatric
patients. Children six months to twelve years were enrolled if they
had symptoms and signs of acute otitis media ("AOM") for less than
four weeks and middle ear effusion by acoustic reflectometry.
Symptoms necessary for enrollment included ear pain or fullness,
discharge from the external auditory canal, decreased hearing or
fever. On physical examination they must have had one or more of
the following: bulging or marked erythema of the tympanic membrane,
loss of the normal light reflex or tympanic membrane landmarks, or
impaired tympanic mobility on biphasic pneumatic otoscopy. The
effusion was to be documented by acoustic reflectometry with an
abnormal reading of 3 or higher. Patients were excluded if they had
a history of hypersensitivity to macrolides or azithromycin, had
been treated with antibiotics in the prior thirty days, had
symptoms of otitis media for longer than four weeks, had
tympanostomy tubes present, or had been receiving antimicrobial
prophylaxis.
[0027] Samples of middle ear fluid were obtained by tympanocentesis
or, in the case of a perforated tympanic membrane, by swab. Middle
ear fluid samples were obtained for culture at baseline. Patients
then received azithromycin 30 mg/kg as a single dose. Children who
vomited within thirty minutes of dosing were redosed.
[0028] Samples of middle ear fluid were split for storage at a
central laboratory and cultured locally. All pathogens isolated
locally were subcultured and sent to a central laboratory for
confirmation and susceptibility testing, performed by Kirby-Bauer
disk-diffusion or MIC testing according to NCCLS standards.
[0029] Polymerase chain reaction (PCR) determination of resistance
mechanisms in all the azithromycin-resistant pneumococci was
done.
[0030] A phone contact occurred on study day 5 to assess for
adverse events followed by visits on days 10 and 24-28, at which
time detailed clinical assessments were made and adverse events
were recorded. Definitions included clinical cure (complete
resolution of all signs and symptoms of AOM); improvement (partial
resolution of signs and symptoms); or failure (no change or
worsening of signs and symptoms, or requirement for additional
antibiotic therapy for AOM). Any patient considered to have failed
therapy was to have a repeat tympanocentesis.
[0031] Statistical Methodology
[0032] The primary endpoint of the trial was the investigator
designated cure rate at Day 24-28 for which a 95% confidence
interval was computed using the normal approximation to the
binomial distribution. Other endpoints analyzed included the
clinical response rate by baseline pathogen at Day 24-28, the
overall clinical response at Day 10, the percentage of subjects
with individual signs and symptoms, as well as findings from
pneumatic otoscopy and acoustic reflectometry. Only Streptococcus
pneumoniae, Moraxella catarrhalis and Haemophilus influenzae were
considered baseline pathogens for the purposes of these
analyses.
[0033] Results
[0034] This trial was an open-label, non-comparative study
conducted at twenty-two sites from the United States, Costa Rica,
Guatemala and Chile.
[0035] A total of 248 patients were entered into the trial of whom
247 received azithromycin. Children were enrolled from sites in the
United States (63%), Costa Rica (16%), Guatemala (13%) and Chile
(8%). The mean age of the children was 3.4 years (range 6 months-12
years). Seventy-two percent (178/248) of the children were noted to
have had previous episodes of otitis media and eight percent
reported a history of sinusitis. The mean duration of symptoms
related to the present episode of acute otitis media was 2.5
days.
[0036] The clinical cure rate, as determined by the investigator,
at day 24-28 was 206/242 (85%) (table 1). Children less than two
years of age had a somewhat lower cure rate (64/83; 77%) while
those greater than two years of age were somewhat more likely to be
cured (142/159; 89%). Similar results were seen at day 10 with an
overall success rate (cure+improvement) of 89% (213/240).
[0037] One hundred twenty four patients had a pathogen identified
at baseline by culture. The clinical cure rate for these subjects
at day 24-28 was 100/124 (81%). Cure rates were highest for
patients with M. catarrhalis isolated at baseline (10/10; 100%)
followed by S. pneumoniae (67/76; 88%) and H. influenzae (28144;
64%). At day 10, the clinical success rate for patients with a
pathogen identified at baseline was 86% (105/122). Success rates by
baseline pathogen were as follows: M. catarrhalis--10/10 (100%); S.
pneumoniae--70/76 (92%); H. influenzae--30/42 (71%).
[0038] All H. influenzae and M. catarrhalis that were isolated were
susceptible to azithromycin. Twelve children were found to have an
infection with an isolate of S. pneumoniae resistant to macrolides
(FIG. 1). Five of the 12 isolates had an MIC of >256 .mu.g/ml.
All five isolates were resistant to clindamycin and on PCR were
found to contain the erm B gene. Only two of these five patients
were cured at day 28. The seven remaining isolates had an MIC of 8
.mu.g/ml, were sensitive to clindamycin and were found to contain
the mef A gene. Six of these seven patients were cured at day 28.
The patient who failed was resolving the disease in the ear from
which the baseline isolate was obtained but had a different S.
pneumoniae isolate recovered on day 4 from the opposite ear. This
second isolate had an MIC of >256 .mu.g/ml, was resistant to
clindamycin and contained the erm B gene. The two isolates also
differed by pulsed field electrophoresis. Nine children had
isolates of S. pneumoniae that were penicillin resistant
(MIC.gtoreq.2 .mu.g/ml). Clinical cure at day 28 was seen in 6 of
these children. The 3 children who failed therapy had isolates with
an MIC>256 .mu.g/ml to macrolides and contained the erm B
gene.
[0039] Ninety-two percent of patients had complete resolution of
their baseline symptoms by day 28. Tympanic membrane motility was
impaired in 93% of patients at baseline, decreasing to 27% by day
10 and 12% at day 24-28. Other objective signs of tympanic membrane
disease were seen in less than 10% of subjects at day 24-28.
Abnormal acoustic reflectometry scores were seen in 214/233 (92%)
of patients at baseline. By day 24-28 completely normal readings
were found in 53% of children with 83% having scores improved from
baseline.
[0040] Adverse events were noted in 30/248 (12.1%) subjects
possibly or probably related to azithromycin. Most common adverse
events were vomiting (6%) and diarrhea (3%).
[0041] Discussion
[0042] The results of this study demonstrate that treatment of
children with otitis media with a single oral dose of azithromycin
was well tolerated and resulted in adequate presumed pathogen
eradication rates. A single dose treatment for acute otitis media
could lead to improved compliance. Moreover, azithromycin is
believed to be the only oral antimicrobial therapy known at this
time that can be delivered in one administration.
[0043] In this study 124/247 (50%) children with AOM had a
bacterial pathogen cultured from the tympanic fluid, similar to
isolation rates from previous trials. Azithromycin given as a
single 30 mg/kg oral dose resulted in clinical cure rates
consistent with those observed after a similar total dose was given
over five days or over three days. Response rates at day 24-28 for
S. pneumoniae and M. catarrhalis are high, and that for H.
influenzae is consistent with other similarly designed clinical
trials (FIG. 2). On pharmacokinetic grounds this outcome can be
explained given that the efficacy of azithromycin is primarily
dependent on the total dose delivered, as measured by the
AUC.sub.24, and not the delivery regimen. The amount of drug
delivered in the first 24 hours is higher with a single dose
regimen compared with either the three day or five day treatment
options. While the contribution of Cmax cannot be excluded, it is
felt that outcome is likely to be best predicted by AUC.sub.24/MIC,
supporting the overall comparability of these results to the three
and five day regimens. Of particular interest was the efficacy in
6/7 patients, whose S. pneumoniae isolates were found to contain
the mef A gene, responsible for efflux-mediated resistance. The S.
pneumoniae isolates having a mef A gene are known as resistant to
macrolides. Azithromycin, which is a macrolide, surprisingly was
able to effectively treat infections caused or mediated by S.
pneumoniae isolates having a mef A gene when administered as a
single dose of 30 mg/kg. The possibility that efflux pump
resistance could be overcome by exposing resistant organisms to
higher concentrations of drug earlier in the course of therapy was
noteworthy.
[0044] In conclusion, treatment of acute otitis media with a single
oral dose of azithromycin was safe and effective therapy, and it
offers a therapeutic alternative that maximizes compliance while
minimizing the burden on the patient and the caregiver.
1TABLE 1 Clinical Outcome by Age Range and Baseline Pathogen. 95%
Confidence Azithromycin Interval Randomized and treated 247 Day 10
Clinical Success (Cure + Improvement) All Subjects 213/240 (89%)
85%, 93% Age < 2 years 69/82 (84%) 76%, 93% Age > 2 years
144/158 (91%) 81%, 96% By pathogen identified at baseline 105/122
(86%) S. pneumoniae 70/76 (92%) M. catarrhalis 10/10 H. influenzae
30/42 (71%) Day 24-28 Clinical Cure All Subjects 206/242 (85%) 80%,
90% Age < 2 years 64/83 (77%) 68%, 87% Age > 2 years 142/159
(89%) 84%, 94% By pathogen identified at baseline 100/124 (81%) S.
pneumoniae 67/76 (88%) PC 23140 10 M. catarrhalis 10/10 H.
influenzae 28/44 (64%)
[0045] Laboratory experiments with azithromycin suggest that it is
the total amount of drug rather than the interval of the drug
dosing regimen that determines the concentration at the infection
site and results in efficacy (Tables 2 and 3). In the acute murine
models challenged with S. pneumoniae, H. influenzae, S. pyogenes,
or E. faecalis, azithromycin was superior in efficacy when given as
a single oral dose as determined by PD.sub.50 measurements. A
PD.sub.50 measurement is the protective dose of a drug required to
protect 50% of a cohort of animals from death when infected at a
lethal level with a given pathogen. These preclinical infection
model data are consistent with what is being observed in clinical
studies supporting the one-day therapy advantage over a more
prolonged course of therapy.
2TABLE 2 The Effect of Dose Regimen on Efficacy of Azithromycin and
Clarithromycin in an Acute Murine Model MIC Dosing Oral PD50
Pathogen Drug (.mu.g/ml) Regimen (mg/kg/day) S. Azithromycin 0.06 3
days 3.8 (3.8-3.9) pyogenes 2 days 2.5 (1.8-3.3) 1 day 1.0
(0.6-1.4) S. Clarithromycin 0.06 3 days 3.1 (2.6-3.7) pyogenes 2
days 2.2 (0.9-3.6) 1 day 11.3 (3.1-19.4) H. Azithromycin 3 days
181.6 (180.1-183.1) influenzae 2 days 49.9 (41.5-58.5) 1 day 25.3
(14.3-36.2) H. Clarithromycin 1 day >200 influenzae E. faecalis
Azithromycin 3 days 59.3 (27.5-91.2) 2 days 42.7 (42.2-43.2) 1 day
14.8 (10.2-19.5) E. faecalis Clarithromycin 3 days 18.8 (7.2-30.3)
2 days 23.7 (5.4-42) 1 day 2.2 (0.9-4.2)
[0046] It appears that the additional component of Cmax (3-fold
better when administered as a single dose vs. the same total dose
administered over 3 days) may also factor into the effectiveness of
the regimen. The data suggest that Peak/MIC as well as AUC/MIC play
important roles in predicting efficacy. Thus, using the same total
therapeutic dose, the duration of treatment with azithromycin can
be reduced and appears to be more efficacious (Tables 2-6). While
AUC/MIC still predicts efficacy, these results reflect the
contribution of additional factors, namely Cmax and azithromycin's
prolonged persistent effects, on efficacy.
[0047] Since inflammatory cells provide a mode of transport to the
infection site and a reservoir for azithromycin at the infection
site, superior delivery to the infection site is believed to occur
when one administers large azithromycin doses as early as practical
during the period where maximal inflammation is associated with the
infection. The higher initial concentration at the infection site
may help prevent less susceptible sub-populations of the pathogens
initially present from becoming established. This has been proposed
as the reason for less in vivo emergence of resistance to
azithromycin compared with clarithromycin in patients who received
either drug for treatment or prophylaxis against M. avium. A
shorter oral dosage regimen would also result in greater patient
compliance, which should contribute to reduced emergence of less
susceptible strains.
3TABLE 3 The Effect of Dose Regimen on Efficacy of Azithromycin and
Clarithromycin in Murine Pulmonary Infection Model. Drug MIC
(.mu.g/ Dosing Oral PD50 Pathogen ml) Regimen (mg/kg/total) S.
pneumoniae Azithromycin 0.06 3 days 49.4 (28.1-70.8) 2 days 27.6
(22.8-32.4) 1 day 20.4 (16.4-24.3) S. pneumoniae Clarithromycin
0.06 3 days >200 2 days >200 1 day >200
[0048] The improvement in the PD.sub.50 for treatment of H.
influenzae was especially noteworthy. These findings have been
extended to a gerbil model of middle ear infection challenged with
two different strains of H. influenzae (Table 4 and FIG. 3). H.
influenzae strains 54A1100 and 54A1218 are non-typable isolates;
54A1218 also carries a TEM-1 .beta.-lactamase. In these
experiments, colony-forming units (CFU) are assessed from the bulla
wash of five gerbils per time point. The ED.sub.50 values reflect
the dose in which the CFU recoverable from the bulla wash is 50% of
the non-treated animals. In the first experiment, azithromycin
administered as a single dose was found to be as efficacious as the
same total dose given over 2 or 3 days (Table 4).
4TABLE 4 The Effect of Dose Regimen on Efficacy of Azithromycin in
the Gerbil Middle Ear Infection Model. MIC Dosing ED50 Pathogen
(.mu.g/ml) Regimen (mg/kg/total) H. influenzae 1 3 days 162.9
(140-185.9) 2 days 138.1 (118.7-157.6) 1 day 138.1
(118.7-157.6)
[0049] However, the in vivo kill kinetics demonstrated that the
one-day dosing therapeutic regimen resulted in the most rapid
eradication of the pathogens (FIG. 3) and, in the case of 54A1100,
was the only dosing regimen that leads to complete clearance. Thus,
a single dose therapy has advantages over a more prolonged course
of therapy.
[0050] Several studies have shown good efficacy for azithromycin as
compared to other commercial antibiotics. For the localized and
intracellular infections, this efficacy correlated with the
sustained high tissue levels of azithromycin. Studies of this
nature continue to be published. For example, of the several
macrolides tested (azithromycin, erythromycin, clarithromycin and
roxithromycin), azithromycin was the only one that was efficacious
after a single oral 10 mg/kg dose in a Mycoplasma pneumoniae
pulmonary infection model in hamsters. This efficacy correlated
with the high Cmax and prolonged exposure for azithromycin in
uninfected lungs compared with other macrolides. In a mouse
Chlamydia trachomatis salpingitis model, azithromycin (.+-. an
anti-inflammatory agent) was superior to doxycycline and ofloxacin
combinations in preserving fertility.
[0051] A hypothesis to explain the transfer of azithromycin from
tissue cells to non-intracellular pathogens growing in contact with
the tissue cells has been proposed. Recently, the results from a
mouse model demonstrated azithromycin administered as a single dose
significantly increased survival versus a pneumococcal challenge
compared with all the other dose regimens. This confirmed our
studies discussed above. These data suggest that the high initial
concentrations of azithromycin favor a good outcome.
[0052] 2.2 Supporting Data
[0053] 2.2.1 Murine Lung Infection Model Challenged with
Streptococcus pneumoniae
[0054] Subject
[0055] Accelerated dosing study. In vivo evaluation of azithromycin
and clarithromycin giving the same total dose over 1, 2 and 3 days
vs. an intranasal lung infection produced by a susceptible
Streptococcus pneumoniae (02J1016) in 21.1 gm CF-1 female mice.
[0056] Comments
[0057] Azithromycin and clarithromycin are both active against the
susceptible Streptococcus pneumoniae 02J1016 that produces a more
slowly developing disease relative to other pneumococcal strains in
the in vivo panel. In this pulmonary infection model 100% mortality
in no-drug controls is not observed until 7 days post-infection.
Clarithromycin was chosen as a comparator to azithromycin because
the pharmacokinetics for these two macrolides are quite different.
While clarithromycin achieves relatively high blood levels quickly
and is cleared fairly rapidly, azithromycin accumulates in tissues
and leeches out slowly over time into the bloodstream yielding
overall lower blood levels than clarithromycin but a much longer
exposure time. Additionally, the research of Craig et al. in
preclinical species suggests that the outcomes observed with
azithromycin best correlate with the PD parameter of the AUC/MIC
and time above MIC for clarithromycin. We modeled the differences
in PK/PD over a longer period. The experiment below was to
determine if the compounds work better against a lung infection
with Streptococcus pneumoniae if the same total dose was given over
a 1, 2, or 3-day period administered using a q.d. therapeutic
regimen.
[0058] Azithromycin performs the best when given once rather than
the total dose being spread out over 3 days. It is important to
note that while the azithromycin one day dosing PD.sub.50 (20.4
mg/kg/regimen) is significantly different than the 3 day dosing
PD.sub.50 (49.4 mg/kg/regimen), both are within the 95% confidence
limits of the 2 day dosing regimen PD.sub.50 (27.6
mg/kg/regimen).
[0059] Clarithromycin fails (PD.sub.50>200 mg/kg/regimen) using
the q.d. regimen regardless as to the duration of therapy. This is
puzzling since clarithromycin has a MIC equivalent to that of
azithromycin against 02J1016 (0.01-0.06 .mu.g/ml). However, since
clarithromycin is cleared more rapidly from the animal and this
infection takes longer to manifest itself and cause mortality, this
is most likely an accurate result. Previous efficacy data with
clarithromycin in this pneumococcal pneumonia model was generated
following BID administration over two days of therapy where
clarithromycin therapy is successful with PD.sub.50s ranging from
5-25 mg/kg.
[0060] Procedure
[0061] Azithromycin and clarithromycin were administered P.O. in
diluent q.d. for 1, 2 or 3 days after an I.N. challenge with
Streptococcus pneumoniae (02J1016).
5 Dose Mice (mg/kg/ Surviving/ PD50 Compound day) Total
(mg/kg/regimen) Azithromycin P.O. 33.3 9/10 Lot #17419-64-1F 8.3
1/10 49.4 MIC 0.02-0.13 .mu.g/ml 2.1 0/10 (28.1-70.8)* 3 day
regimen 0.52 0/10 Azithromycin P.O. 50.0 9/10 Lot #17419-64-1F 12.5
4/10 27.6 MIC 0.02-0.13 .mu.g/ml 3.12 0/10 (22.8-32.4) 2 day
regimen 0.78 0/10 Azithromycin P.O. 100.0 10/10 Lot #17419-64-1F
25.0 7/10 20.4 MIC 0.02-0.13 .mu.g/ml 6.25 1/10 (16.4-24.3) 1 day
regimen 1.56 0/10 Clarithromycin P.O. 66.7 2/10 Lot #34844-174-01
16.7 0/10 >200 MIC 0.01-0.06 .mu.g/ml 4.2 0/10 3 day regimen
1.04 0/10 Clarithromycin P.O. 100.0 1/10 Lot #34844-174-01 25.0
0/10 >200 MIC 0.01-0.06 .mu.g/ml 6.25 0/10 2 day regimen 1.56
0/10 Clarithromycin P.O. 200.0 4/10 Lot #34844-174-01 50.0 1/10
>200 MIC 0.01-0.06 .mu.g/ml 12.5 1/10 1 day regimen 3.12 0/10
Infected (non-treated) control 10-1 dilution 0/10 10-2 dilution
0/10 (used in study) 10-3 dilution 0/10 BHI 10/10 (non-infected
control) *95% confidence limits Bacterial challenge: 2.88 *
10.sup.4 organisms/mouse
[0062] 2.2.2 Murine Acute Infection Model Challenged with
Streptococcus pyogenes
[0063] Subject
[0064] Accelerated dosing study. In vivo evaluation of azithromycin
and clarithromycin giving the same total dose over 1, 2 and 3 days
vs. an acute infection produced by a susceptible Streptococcus
pyogenes (02C0203) in 14.2 gm CF-1 mixed mice.
[0065] Comments
[0066] Azithromycin and clarithromycin are both active against the
susceptible Streptococcus pyogenes 02C0203. The outcomes for
various lengths of therapy were compared in this infection model,
because the peritonitis caused by this strain lends itself to
prolonged therapy as 100% mortality doesn't occur until 2-3 days
post-challenge. Clarithromycin was chosen as a comparator to
azithromycin because the pharmacokinetics for these two macrolides
are quite different. While clarithromycin achieves relatively high
blood levels quickly and is cleared fairly rapidly, azithromycin
accumulates in tissues and leeches out slowly over time into the
bloodstream yielding overall lower blood levels than clarithromycin
but a much longer exposure time. Additionally, the research of
Craig et al. in preclinical species suggests that the outcomes
observed with azithromycin best correlate with the PD parameter of
the AUC/MIC and time above MIC for clarithromycin. See Craig, W. et
al. (1997), "Postantibiotic effects and dosing of macrolides,
azalides and streptogramins", in Expanding Indications of the New
Macrolides, Azalides, and Streptogramins (Zinner S H, Young L S,
Acar J F, Neu H C, eds.) pp. 27-38, Marcel Dekker, New York. This
experiment was to determine if the compounds work better against a
lung infection with Streptococcus pyogenes acute infection giving
the same total therapeutic dose over a 1, 2, or 3-day dosing
period. In this same type of experiment with a susceptible
Streptococcus pneumoniae (02J1016) it was found that azithromycin
performs best when administered in one dose rather than spreading
the same total dose out over 3 days. All three regimens of
clarithromycin failed (PD.sub.50s>200 mg/kg), so no useful
information was gleaned from that portion of the experiment except
to say that when therapy was administered using a b.i.d. regimen
the PD.sub.50s were in the range of 5-25 mg/kg.
[0067] Against 02C0203, azithromycin performs the best when given
once rather than the total dose being spread out over 3 days. The
azithromycin 1 day dosing PD.sub.50 (1.0 mg/kg/regimen) is
significantly different than the 2 and 3 day dosing PD.sub.50s (2.5
and 3.8 mg/kg/regimen, respectively). The 2 and 3 day dosing
regimen PD.sub.50s are also significantly different from each
other.
[0068] Clarithromycin has the best activity when given more often
(2-days and 3-days dosing versus 1-day dosing). The PD.sub.50s for
the 2 and 3-day dosing regimens (3.1 and 2.2 mg/kg/regimen) are
equivalent, while the PD.sub.50 for the 1-day dosing regimen, 11.3
mg/kg/regimen), is clearly higher. However, when the 95% confidence
limits for all three regimens are taken into account, it appears as
though all three regimens are equivalent. The 2 and 3-day therapies
are more consistent with historical data for clarithromycin
administered b.i.d. for 1-day.
[0069] Procedure
[0070] Azithromycin and clarithromycin were administered P.O. in
diluent q.d. for either 1, 2 or 3 days after an I.P. challenge with
Streptococcus pyogenes (02C0203) starting 1.0 hour after
infection.
6 Dose Mice (mg/kg/ Surviving/ PD50 Compound day) Total
(mg/kg/regimen) Azithromycin P.O. 12.5 10/10 Lot #17419-64-1F 3.12
10/10 3.8 MIC 0.01-0.10 .mu.g/ml 0.78 3/10 (3.8-3.9)* 3 day regimen
0.20 0/10 Azithromycin P.O. 25.0 9/10 Lot #17419-64-1F 6.25 10/10
2.5 MIC 0.01-0.10 .mu.g/ml 1.56 7/10 (1.8-3.3) 2 day regimen 0.39
1/10 Azithromycin P.O. 50.0 10/10 Lot #17419-64-1F 12.5 10/10 1.0
MIC 0.01-0.10 .mu.g/ml 3.12 8/10 (0.6-1.4) 1 day regimen 0.78 3/10
Clarithromycin P.O. 12.5 10/10 Lot #34844-174-01 3.12 9/10 3.1 MIC
0.01-0.03 .mu.g/ml 0.78 5/10 (2.6-3.7) 3 day regimen .20 0/10
Clarithromycin P.O. 25.0 8/10 Lot #34844-174-01 6.25 9/10 2.2 MIC
0.01-0.03 .mu.g/ml 1.56 8/10 (0.9-3.6) 2 day regimen 0.39 0/10
Clarithromycin P.O. 50.0 10/10 Lot #34844-174-01 12.5 6/10 11.3 MIC
0.01-0.03 .mu.g/ml 3.12 4/10 (3.1-19.4) 1 day regimen 0.78 0/10
Infected (non-treated) control 10-1 dilution 0/10 10-2 dilution
0/10 (used in study) 10-3 dilution 0/10 BHI (non-infected control)
10/10 *95% confidence limits Bacterial challenge: 1 * 10.sup.6
organisms/mouse
[0071] 2.2.3 Murine Acute Infection Model Challenged with
Haemophilus influenzae
[0072] Subject
[0073] Accelerated dosing paradigm. In vivo evaluation of
azithromycin vs. an acute infection of Haemophilus influenzae
54A1100 (non-type B) in 20 gram [F] DBA/2 mice comparing equivalent
therapies (same total therapeutic dose) administered over 1, 2 and
3 days. One set of clarithromycin-dosed mice was also tested, with
total dose administered in just one day.
[0074] Discussion
[0075] Improved in vivo efficacy has been shown for azithromycin in
preclinical infection models with S. pneumoniae, S. pyogenes, (both
supra) and Enterococcus faecalis (infra) when the total therapeutic
dose is administered in an accelerated fashion (one day of therapy
vs. two or three). Hemophilus influenzae 54A1100 also produces a
more slowly developing disease relative to more acutely lethal
pathogens used in the in vivo models. Azithromycin had previously
been tested in the mouse systematic disease (PD50) model utilizing
a standard dosing paradigm (b.i.d. on day 1) and had a PD50 of 27
mg/kg. s.c. vs 54A1100. Because in this model 100% mortality is not
seen until day 2 in the no drug controls, one is able to evaluate
the influence of therapy duration on survival.
[0076] In this study, for azithromycin the same total therapeutic
dose (i.e., 200 mg/kg/therapeutic regimen) was administered Q.D. on
day one (i.e., 200 mg/kg on day 1), Q.D. on day one and two (i.e.,
100 mg/kg on day 1 and 3) or Q.D. on day one, two and three (i.e.,
67 mg/kg on day 1, 2 and 3). For azithromycin, efficacy was best
with one therapeutic dose (25.3 mg/kg s.c.) and this accelerated
dosing regimen was significantly better (p<0.05) than the 2 and
3-day regimens. Furthermore, the 2-day regimen was also
significantly better than the 3-day regimen (p<0.05).
Clarithromycin (with a one day dose regimen and an MIC of 8
.mu.g/ml) failed (PD50: >200 mg/kg s.c.).
7 Dose Mice (mg/kg/ Surviving/ PD50 Compound day) Total
(mg/kg/regimen) Azithromycin s.c. 200 10/10 25.3 (17419-064-1F) 50
9/10 .sup. (14.3-36.2).sup.1 MIC: 0.5-1 .mu.g/ml 12.5 1/10 Q.D. [1
day] 3.12 0/10 Azithromycin 100 10/10 49.9 (17419-64-1F) 25 5/10
(41.5-58.5) Q.D. [2 days] 6.25 1/10 1.56 0/10 Azithromycin 66.6
6/10 181.6 (17419-064-1F) 16.6 0/10 (180.1-183.1) Q.D. [3 days]
4.15 0/10 1.04 0/10 Clarithromycin 200 0/10 >200 (4844-174-01)
50 2/10 MIC: 8 .mu.g/ml 12.5 0/10 Q.D. [1 day] 3.12 0/10 Infected
only 0/10 dilution 10.sup.-2 dilution 10.sup.-3 0/10 dilution
10.sup.-4 0/10 3% yeast 10/10 Bacterial challenge: 1 * 10.sup.7 per
mouse .sup.195% confidence limits
[0077] 2.2.4 Murine Acute Infection Model Challenged with
Enterococcus faecalis
[0078] Subject
[0079] Accelerated dosing paradigm. In vivo evaluation of
azithromycin and clarithromycin vs. an acute infection of
Enterococcus faecalis 03A1085 in 22 gram [F] DBA/2 mice comparing
equivalent therapies (same total therapeutic dose) administered
over 1, 2 and 3 days.
[0080] Discussion
[0081] Previous experiments demonstrated improved in vivo efficacy
for azithromycin in preclinical infection models with S. pneumoniae
and S. pyogenes (both supra) when the total therapeutic dose is
administered in an accelerated fashion (one day of therapy vs. two
or three). Azithromycin and clarithromycin are both active against
the susceptible Enterococcus faecalis 03A1085 that also produces a
more slowly developing disease relative to more acutely lethal
pathogens used in the in vivo models. Azithromycin and
clarithromycin had previously been tested in the mouse systemic
disease (PD50) model utilizing a standard dosing paradigm (b.i.d.
on day 1) and had PD50's of 10.1 mg/kg s.c. and 1.7 mg/kg. s.c.,
respectively, vs. 03A1085. Because 100% mortality does not occur in
this model until day 2-3 in the no drug controls, the experiment
allows one to evaluate the influence of therapy duration on
survival.
[0082] In this study, the same total therapeutic dose (i.e., 200
mg/kg/therapeutic regimen) was administered Q.D. on day one (i.e.,
200 mg/kg on day 1), Q.D. on day one and two (i.e., 100 mg/kg on
day 1 and 3) or Q.D. on day one, two and three (i.e., 67 mg/kg on
day 1, 2 and 3). For azithromycin, efficacy was best with one dose
(14.8 mg/kg s.c.) and this accelerated dosing regimen was
significantly better (p<0.05). Interestingly, clarithromycin
efficacy was also best with one dose (2/2 mg/kg s.c.), and as with
azithromycin, the one-dose confidence limits did not overlap with
the 2 and 3-day regimens. However, the data for the 2-day and 3-day
regimens were indistinguishable.
8 Dose Mice (mg/kg/ Surviving/ PD50 Compound day) Total
(mg/kg/regimen) Azithromycin s.c. 200 10/10 14.8 (17419-064-1F) 50
9/10 .sup. (10.2-19.5).sup.1 MIC: 3-6 .mu.g/ml 12.5 4/10 Q.D. [1
day] 3.12 1/10 w/serum: 6.25 Azithromycin 100 10/10 42.7
(17419-064-1F) 25 7/10 (42.2-43.2) Q.D. [2days] 6.25 0/10 1.56 1/10
Azithromycin 66.6 9/10 59.3 (17419-064-1F) 16.6 4/10 (27.5-91.2)
Q.D. [3 days] 4.15 2/10 1.04 3/10 Clarithromycin 100 10/10 2.2
(34844-174-01) 25 10/10 (0.19-4.2) MIC: 3.12 .mu.g/ml 6.25 7/10
Q.D. [1 day] 1.56 3/10 w/serum: 3.12 Clarithromycin 50 10/10 23.7
(34844-174-01) 12.5 6/10 (5.4-42) Q.D. [2 days] 3.12 5/10 0.78 1/10
Clarithromycin 33.3 9/10 2.2 (34844-174-01) 8.3 8/10 (0.19-4.2)
Q.D. [3 days] 2.08 1/10 0.52 3/10 Infected only 0/10 18.8 dilution
10.sup.-2 dilution 10.sup.-3 .sup. 1/10.sup.2 (7.2-30.3) dilution
10.sup.-4 0/10 3% yeast 10/10 Bacterial challenge: 1 .times.
10.sup.7 per mouse .sup.195% confidence limits .sup.2PD50
adjusted
[0083] 2.2.5 Accelerated Dosing Paradigm in the Gerbil Middle Ear
Infection Model with Infection of Haemophilus influenzae
54A1100
[0084] Subject
[0085] Accelerated dosing paradigm in the gerbil middle ear
infection model. In vivo evaluation of azithromycin vs. a localized
infection of Haemophilus influenzae 54A1100 (non-type B) in 50.4
gram [F] Mongolian gerbils comparing one equivalent therapy [200
mg/kg/therapy p.o.] (same total therapeutic dose) administered over
1, 2, or 3 days. CFU counts/mi. bulla wash (5 gerbils per time
point) were taken at 24, 48, 72, and 96 hours post-infection for
each of the Q.D. 1, Q.D. 2, and Q.D. 3 groups.
[0086] Discussion
[0087] In this study based on a mg/kg/total regimen for
azithromycin the same therapeutic dose (i.e., 200 mg/kg/therapeutic
regimen) was administered Q.D. on day one (i.e., 200 mg/kg on day
1), Q.D. on day one and two (i.e., 100 mg/kg on day 1 and 2) or
Q.D. on day one, two and three (i.e., 66.6 mg/kg on day 1, 2 and
3). A baseline CFU count of bulla wash was measured 24 hours
post-infection, before dosing began. Thereafter, samples for counts
from each group were taken at 48, 72, 96 hours post-infection. By
looking at the kinetics of bacterial reduction in the bulla wash, a
kinetic kill curve could be constructed which was designed to
visually elucidate the observed in vivo therapeutic efficacy by
examining the dose/time-kill relationship (FIG. 3a).
[0088] Summary
[0089] In past studies of accelerated dosing with azithromycin vs.
54A1100 (in the gerbil), Q.D. 1, O.D. 2, and Q.D. 3 therapies had
equivalent activity (ED50's of 138.1, 138.1, and 162.7 mg/kg/total
regimen, respectively). It did not matter if dosing began at 24 or
72 hours post-infection. This study indicates the importance of
dose related (concentration) kill over time. For Q.D. 1, activity
appeared to be cidal at the 200 mg/kg p.o. level (i.e., there was
<log 2.0000 bacterial load at 48 hours post-infection (24 hours
post-dose) and there was no re-growth at 72-96 hours
post-infection). For Q.D. 2, at 48 hours post-infection (24 hours
post-last-dose), cfu counts were reduced relative to infected
control [P=0.0250] and eradication was observed in 4/5 test
subjects at 72 hours post-infection (24 hours post-last-dose),
P=0.0000, and at 96 hours post-infection (48 hours post-last-dose),
P=0.0105. For Q.D. 3, at 48 hours post-infection (24 hours
post-last-dose) bacterial reduction relative to infected control
was not significant (P=0.8540) and while the bacterial burden was
reduced at 72 and 96 hours post-infection, eradication was not
observed in any test subject; 72 hours post-infection (24 hours
post-last-dose), P=0.0007 and at 96 hours post-infection (24 hours
post-last-dose), P=0.0902. The Q.D. 2 and Q.D. 3 therapies
demonstrated antibacterial activity, but not total clearance and
with possibly a slight re-growth by 96 hours post-infection (see
graph below). In these two groups (in animals not cleared or
.gtoreq.log 2.0000 cfu/ml bulla wash), concern for development of
bacterial resistance arises because the bacterial load that is
present is exposed to implicitly sub-therapeutic concentrations of
antibiotic for the duration of the therapeutic evaluation (no
susceptibilities were determined to address this point). Q.D. 1 at
the 200 mg/kg p.o. level demonstrated the best activity with total
clearance being demonstrated early on in therapy. This observation
implies that the likelihood of development of resistance using this
accelerated regimen would be diminished relative to the 2-3 day
therapy.
9 Dose Sample Time Recoverable (mg/kg/ [hours] CFU (Bulla) [ day)
Post- Log.sub.10 .multidot. Geo .multidot. Mean] Compound oral
Infection (SEM) P-value.sup.2 Azithromycin 200 24 7.3206
(0.28).sup.1 (17419-064-1F) 48 <2.0000 P = .0000 Q.D. [1 day] 72
<2.0000 P = .0001 96 <2.0000 P = .0001 Azithromycin 100 24
7.3206 (0.28).sup.1 Q.D. 2 [2 days] 48 5.7572 (0.54) P = .0250 Q.D.
2 72 <2.4580 (0.46) P = .0000 (continued) 96 <3.1112 (1.11) P
= .0105 Azithromycin 66.6 24 7.3206 (0.28).sup.1 Q.D. [3 days] 48
5.8817 (0.44) P = .8540 72 4.5981 (0.14) P = .0007 96 6.1520 (0.75)
P = .0902 Infected only -- 24 7.3206 (0.28).sup.1 48 7.2491 (0.26)
72 7.8242 (0.41) 96 7.7274 (0.33) Bacterial challenge: 1 .times.
10.sup.4/gerbil .sup.124 hours post-infection baseline count done
before dosing begins (SEM) .sup.2P-value: infected/dosed compared
to infected only of same timepoint
[0090]
10 Summary: cfu counts in bulla wash samples at 48, 72, and 96
hours post infection P-value [dosed to Hrs. post infected only of
same Group Infection Geo. Mean SD SEM timepoint group] QD1 48
<2.0000 P = .0000 QD2 48 5.7572 1.2 0.54 P = .0250 QD3 48 5.8817
0.99 0.44 P = .8540 Infected 48 7.2491 0.57 0.26 QD1 72 <2.0000
P = .0001 QD2 72 <2.4580 1.02 0.46 P = .0000 QD3 72 4.5981 0.3
0.14 P = .0007 Infected 72 7.8242 0.92 0.41 QD1 96 <2.0000 P =
.0001 QD2 96 <3.1112 2.48 1.11 P = .0105 QD3 96 6.1520 1.67 0.75
P = .0902 Infected 96 7.7274 0.73 0.33 Note: 24 hour cfu counts
(before dosing began): 7.3206 [log of cfu-bulla wash/ml]
[0091] 2.2.6 Accelerated Dosing Paradigm in the Gerbil Middle Ear
Infection Model with Haemophilus influenzae 54A1218
[0092] Subject
[0093] Accelerated dosing paradigm in the gerbil middle ear
infection model. In vivo evaluation of azithromycin vs. a localized
infection of Haemophilus influenzae 54A1218 (non-typeable/beta
lactamase+) in a 49.4 gram [F] Mongolian gerbils comparing one
equivalent therapy [200 mg/kg/therapy p.o.] (same total therapeutic
dose) administered over 1, 2, or 3 days. CFU counts/mi. bulla wash
(5 gerbils per timepoint) were done at 24, 48, 72, and 96 hours
post-infection for each of the Q.D. 1, Q.D. 2, and Q.D. 3
groups.
[0094] Discussion
[0095] In this study based on a mg/kg/total regimen for
azithromycin, the same therapeutic dose (i.e., 200
mg/kg/therapeutic regimen) was administered Q.D. on day one (i.e.,
200 mg/kg on day 1), Q.D. on day one and two (i.e., 100 mg/kg on
day 1 and 2) or Q.D. on day one, two and three (i.e., 66.6 mg/kg on
day 1, 2 and 3). A baseline CFU count of bulla wash was done 24
hours post-infection, before dosing began. Thereafter, samples for
counts from each group were taken at 48, 72, 96 hours
post-infection. By looking at the kinetics of bacterial reduction
in the bulla wash, a kinetic kill curve could be constructed with
the goal of visually showing the observed in vivo therapeutic
efficacy by examining the dose/time-kill relationship (FIG.
3b).
[0096] Summary
[0097] In past studies of accelerated dosing with azithromycin vs.
54A1218 (in the gerbil), Q.D. 1, Q.D. 2, and Q.D. 3 therapies had
equivalent activity (ED50's of 83.8 (53.6-114.1), 53.4 (21.2-85.5),
and 65.2 (51-79.4) and 162.7 mg/kg/total regimen, respectively).
This study indicates the importance of dose related (concentration)
kill over time. For Q.D. 1, activity appeared to be cidal at the
200 mg/kg p.o. level (i.e., there was log <2.0602 bacterial load
at 48 hours post-infection (24 hours post-dose) and there was no
re-growth at 72-96 hours post-infection). For Q.D. 2, at 48 hours
post-infection (24 hours post-last-dose), cfu counts were reduced
relative to infected control [P=0.0338] and eradication was
observed at 72 and 96 hours post-infection. For Q.D. 3, at 48 hours
post-infection (24 hours post-last-dose) bacterial reduction
relative to infected control was not significant (P=0.1 889), but
at 72 and 96 hours post-infection eradication was observed. Q.D. 1,
Q.D. 2, and Q.D. 3 therapies were all effective at eradicating the
organism by 72 hours post infection. Q.D. 1 at the 200 mg/kg p.o.
level demonstrated the best activity with total clearance being
demonstrated early on in therapy (48 hours post infection; 24 hours
post-last-dose) and this observation implies that the likelihood of
development of resistance using this accelerated regimen would be
somewhat diminished relative to the 2-3 day therapy. These data are
consistent with the results that were observed vs. strain 54A1100
(non-type B H. influenzae) except that there is eradication with
all azithromycin regimens by 72 hours post-challenge with this
strain.
11 Dose Sample Time Recoverable (mg/kg/ [hours] CFU (Bulla) [ day)
Post- Log.sub.10 .multidot. Geo .multidot. Mean] Compound oral
Infection (SEM) P-value.sup.2 Azithromycin 200 24 7.7206
(0.15).sup.1 (17419-064-1F) 48 <2.0000 P = .0000 Q.D. [1 day] 72
<2.0602 P = .0000 96 <2.0000 P = .0000 Azithromycin 100 24
7.7206 (0.15).sup.1 Q.D. 2 [2 days] 48 <3.8587 (1.04) P = .0338
Q.D. 2 72 <2.0000 P = .0001 (continued) 96 <2.0000 P = .0000
Azithromycin 66.6 24 7.7206 (0.15).sup.1 Q.D. [3 days] 48
<5.2399 (1.21) P = .1889 72 <2.0000 P = .0001 96 <2.0000 P
= .0000 Infected only -- 24 7.7206 (0.15).sup.1 48 7.1691 (0.09) 72
7.7736 (0.2).sup.3 96 7.7274 (0.33) Bacterial challenge: 1.2
.times. 10.sup.6/gerbil .sup.124 hours post-infection baseline
count done before dosing begins (SEM) .sup.2P-value: infected/dosed
compared to infected only of same timepoint .sup.3There were four
gerbil samples in this group; all other groups had five
samples/group
[0098]
12 P-value [dosed to infected Hours % only of same Post Geo.
Clearance timepoint Group Infection Mean of Group SD SEM group] QD1
48 <2.0000 100% P = .0000 QD2 48 <3.857 40% 2.32 1.04 P =
.0338 QD3 48 <5.2399 40% 2.71 1.21 P = .1889 Infected 48 7.1691
0% 0.22 0.098 QD1 72 <2.0602 100% 0.13 0.06 P = .0000 QD2 72
<2.0000 100% P = .0001 QD3 72 <2.0000 100% P = .0001 Infected
72 7.7736** 0% 0.39 0.2 QD1 96 <2.0000 100% P = .0000 QD2 96
<2.0000 100% P = .0000 QD3 96 <2.0000 100% P = .0000 Infected
96 7.4296 0% 0.51 0.23 Note: 24 hour cfu counts (before dosing
began): 7.7206 [log of cfu-bulla wash/ml] <1 .times. 10.sup.3
cfu/ml considered negative; .gtoreq.1 .times. 10.sup.3 considered
positive **4 samples in this group; all others had 5 samples
[0099] 2.2.7 Accelerated Dosing of Azithromycin in Preclinical
Models
[0100] The results from the following study show the comparative in
vivo activity of azithromycin following one-, two-, three-day
dosing regimens in preclinical species infection models. The
localized gerbil otitis media model was utilized to evaluate the in
vivo kill kinetics of azithromycin using these three dosing
regimens. Additionally, the serum and pulmonary tissue
pharmacokinetics of azithromycin in mice were characterized for the
three dosing intervals.
[0101] Materials and Methods
[0102] MIC Determinations. Streptococcus pneumoniae, S. pyogenes,
E. faecalis, and H. influenzae MICs were determined using the broth
microdilution procedure recommended by the NCCLS. Test trays were
incubated at 35C without carbon dioxide. For testing of
streptococci, the cation-adjusted Mueller-Hinton broth was
supplemented with 2-3% lysed horse blood. For testing H.
influenzae, freshly prepared Haemophilus Test Medium broth was
used.
[0103] Bacterial Strains.
[0104] S. pneumoniae 02J1016, serotype 3, originally isolated from
blood culture (strain P 4241) (MLS- and
penicillin-susceptible).
[0105] S. pyogenes 02C0203, ATCC 12384, group A, type 3
(MLS-susceptible).
[0106] E. faecalis 03A1085, vancomycin susceptible clinically
derived strain.
[0107] H. influenzae 54A1100, (43095 ATCC Fulghum strain)
non-serotype B strain originally isolated from otitis media
(macrolide and penicillin susceptible).
[0108] H. influenzae 54A1218, clinically derived non-serotype B
strain (macrolide-susceptible, penicillin-resistant, TEM-1
beta-lactamase).
[0109] Animals.
[0110] Female Swiss (CF-1) mice, 5-6 weeks of age (18-20 g): S.
pneumoniae/pyogenes.
[0111] Female DBA/2 mice, 5-6 weeks of age (18-20 g): H.
influenzae.
[0112] Female Mongolian gerbils, 6-7 weeks of age (45-50 g): H.
influenzae.
[0113] Models of Infection.
[0114] Peritonitis Model: Mice were infected intraperitoneally with
a 10 LD.sub.100 inoculum of the culture. With enterococcal and
haemophilus strains, the inoculum was fortified with 3% Brewers
yeast as a bacterial enhancing adjuvant. Oral therapy was initiated
at 0.5 after the bacterial challenge (n=30 mice per dose level) and
administered QD over one, two, and three days (same total
therapeutic dose administered over different dosing intervals).
Survivors were recorded over 7 days at which time ED.sub.50s were
determined from the survival data at day five using non-linear
regression techniques.
[0115] S. pneumoniae pneumonia model: Mice were infected
intranasally with an LD.sub.100 inoculum of a log phase
pneumococcal culture (about 10.sup.4 CFU per mouse). Oral therapy
was initiated at 18 h following bacterial challenge and was
administered QD for one, two, or three days (n=30 mice per dose
level). Survivors were recorded for 10 days at which time
ED.sub.50s were determined from the survival data at day ten using
the non-linear regression techniques.
[0116] H. influenzae therapeutic model: Gerbils were infected with
about 10.sup.3-4 CFU of H. influenzae via intra-bulla instillation.
Oral therapy was initiated 18 h following challenge and consisted
of QD dosing for 1, 2, and 3 days (n=10 gerbils per dose level).
Bulla were tapped, washed with 100 microliter of saline and
recoverable H. flu enumerated (limit of detection was 100 CFU).
ED.sub.50 values were estimated from the clearance data (% of
animals that cleared the H. flu culture) over the evaluated dosage
range.
[0117] H. influenzae in vivo time kill: Gerbils were infected with
about 10.sup.3-4 CFU of H. flu via intrabulla instillation. Oral
therapy was initiated 24 h following challenge and consisted of QD
dosing of 200 mg/kg for one, two, and three days with the same
total therapeutic dose being administered to each group (n=5).
Bulla were tapped at 24, 48, 72 and 96 hours following challenge,
washed with saline and recoverable H. flu enumerated (limit of
detection was 100 CFU).
[0118] Pharmacokinetics.
[0119] Female CF-1 mice were orally administered azithromycin at
100 mg/kg QD for one day, 50 mg/kg QD for two days and 33 mg/kg QD
for three days. Azithromycin was formulated in a 0.5%
methylcellulose vehicle. Blood and pulmonary tissue samples were
taken starting at 0.5 h post-dose and at predetermined intervals
over a 96 h period. Plasma and lung samples were prepared and
maintained at -70C. Plasma and pulmonary tissue concentrations of
azithromycin were determined by a non-validated LC/MS assay using
Turbo IonSpray mass spectrometry detection. The lower limit of
quantification (LLOQ) was 50 ng/ml. The upper limit of
quantification (ULOQ) was 1.25 .mu.g/ml. Interassay variability was
<7%. Pharmacokinetic parameters were calculated using the
non-compartmental method by WinNonlin 2.1 (Scientific Consulting,
Inc.).
[0120] Results
[0121] In peritonitis models, bacterial strains were chosen on
their ability to produce a more chronic disease (time to mortality
in infected controls was 2-3 days) so that prolonged therapy could
be evaluated. Against isolates of S. pyogenes, S. pneumoniae, E.
faecalis and H. influenzae, a one-day QD therapeutic regimen of
azithromycin was superior to a two- and/or three-day QD regimen
(Table 5). Comparison of similar dosing regimens with
clarithromycin was equivocal.
13TABLE 5 INFLUENCE OF DOSING REGIMEN ON THE THERAPEUTIC ACTIVITY
OF AZITHROMYCIN AND CLARITHROMYCIN IN MURINE PERITONITIS MODELS
ED.sub.50 values for various dosing regimens One-Day Two-Day
Three-Day Therapy Therapy Therapy MIC (mg/kg/ (mg/kg/ (mg/kg/ Drug
(.mu.g/ml) therapy) therapy) therapy) Streptococcus pyogenes
02C0203 Azithromycin 0.03 0.78.sup.1 1.1 1.25 Clarithromycin 0.03
11.7.sup.1 2.5 3.8 Streptococcus pneumoniae 02J1016 Azithromycin
0.10 8.7.sup.1 7.6 15.1 Clarithromycin 0.05 99.8 103.0 87.5
Enterococcus faecalis 03A1085 Azithromycin 6.25 12.7.sup.1 44.5
44.4 Clarithromycin 3.12 6.1 16.6 23.1 Haemophilus influenzae
54A1100 Azithromycin 1.56 30.3.sup.1 48 147 Clarithromycin 8
>200 >200 >200 .sup.1Indicates that One-Day therapy
ED.sub.50 value is significantly different from two- and/or
three-day therapies
[0122] Similarly, in a murine pneumococcal pneumonia model one-day
azithromycin therapy was superior to the three-day regimen (Table
6). For clarithromycin, the dosing regimen did not impact outcome,
as the ED.sub.50 values were comparable regardless of dosing
interval. QD dosing of clarithromycin is sub-optimal in this
model.
14TABLE 6 INFLUENCE OF DOSING REGIMEN ON THE THERAPEUTIC ACTIVITY
OF AZITHROMYCIN AND CLARITHROMYCIN IN A MURINE PNEUMONIA MODEL
ED.sub.50 values for various dosing regimens One-Day Two-Day
Three-Day Therapy Therapy Therapy MIC (mg/kg/ (mg/kg/ (mg/kg/ Drug
(.mu.g/ml) therapy) therapy) therapy) Streptococcus pneumoniae
02J1016 Azithromycin 0.10 20.sup.1 27 49 Clarithromycin 0.05 270
327 338 .sup.1Indicates that One-Day therapy ED.sub.50 value is
significantly different from two- and/or three-day therapies
[0123] The length of therapy did not have an impact on the
therapeutic activity of azithromycin against two non-type B strains
of H. influenzae in the gerbil otitis media infection model (see
Table 7). Because the gerbil does not metabolize clarithromycin to
14-hydroxyclarithromycin and dosing of clarithromycin was not
optimized, clarithromycin failed in this model. Although the
results for Augmentin.RTM. amoxicillin/clavulanate potassium
(manufactured by GlaxoSmithKline, Inc.) show that the absolute
ED.sub.50 using the three-day regimen was lower than for the two-
or one-day regimens, this was not statistically significant.
15TABLE 7 INFLUENCE OF DOSING REGIMEN ON THE THERAPEUTIC ACTIVITY
OF AZITHROMYCIN AND COMPARATOR IN GERBIL OTITIS MEDIA MODELS
ED.sub.50 values for various dosing regimens One-Day Two-Day
Three-Day Therapy Therapy Therapy MIC (mg/kg/ (mg/kg/ (mg/kg/ Drug
(.mu.g/ml) therapy) therapy) therapy) Haemophilus influenzae
54A1100 Azithromycin 1.56 138 138 163 Clarithromycin 8 >200
>200 >200 Haemophilus influenzae 54A1218 Azithromycin 0.78 84
53 65 Augmentin 1 72 100 55
[0124] The in vivo kill kinetics for azithromycin (200
mg/kg/therapy) against a penicillin-susceptible H. influenzae
strain suggest that one-day therapy rapidly eradicates the pathogen
while extended therapies do not clear the pathogen (FIG. 3).
Against a penicillin-resistant H. influenzae isolate a similar
profile was observed with a more rapid eradication using the
one-day therapy (FIG. 3). In contrast, Augmentin.RTM.
amoxicillin/clavulanate potassium (manufactured by GlaxoSmithKline,
Inc.) rapidly killed the pathogen with the one-day regimen. The
three-day regimen, however, resulted in improved persistent effects
relative to the one-day and two-day regimens (see FIG. 4).
[0125] The serum and pulmonary tissue pharmacokinetics of
azithromycin were characterized at a total dose of 100 mg/kg dose
administered over one, two, and three days (Table 8 and FIG. 5).
The serum and pulmonary tissue exposures are independent of dosing
regimen. T.sub.max varies significantly. C.sub.max is dependent on
the dosing interval with the one-day regimen resulting in the
highest C.sub.max.
16TABLE 8 COMPARISON OF AZITHROMYCIN SERUM AND PULMONARY PK
PARAMETERS FOLLOWING A TOTAL DOSE OF 100 MG/KG ADMINISTERED QD OVER
1, 2 AND 3 DAYS Individual Total Dose Days of Dose C.sub.max
T.sub.max AUC.sub.(0-tlast) (mg/kg) Dosing (mg/kg/dose) (mcg/ml)
(hr) (mcg * h/ml) Serum PK 100 1 100 2.1 2 18.8 100 2 50 1.3 26
15.9 100 3 33.3 0.98 26 19.8 Pulmonary PK 100 1 100 40 4 970 100 2
50 31 28 870 100 3 33.3 28 12 1048
[0126] In sum, these results show the relative efficacy of one-,
two- and three-day dosing regimens of azithromycin in three
preclinical infection models using primarily relevant bacterial
pathogens. These efficacy data indicate that a one-day dosing
regimen is better or at the very least equivalent to a longer
course of therapy. The pharmacokinetics of azithromycin is
consistent with the observed pharmacodynamics in these models.
Additionally, the in vivo kill kinetics of azithromycin against H.
influenzae suggest that bacterial clearance is more rapid with a
one-day dosing regimen. This attribute may have benefits in
suppressing the emergence of resistant strains. In sum, these
preclinical infection model data correspond with the clinical
studies supporting the advantages of one-day therapy over a more
prolonged course of therapy.
[0127] 2.3 Macrolide Resistance Studies in Humans
[0128] The results from two in vivo human studies for otitis media
are summarized in view of the resistance data they provide.
Relevant features of the testing are summarized also.
[0129] 2.3.1 Human Studies: Antimicrobial Susceptibility
Testing
[0130] Cultures were taken for antimicrobial susceptibility testing
and bacterial species were identified. Current NCCLS approved
breakpoints for MICs and zone sizes were applied to all data
irrespective of the breakpoint in use at the time of the study. The
isolates from the clinical studies were sent to central
laboratories for identification and susceptibility determination.
The methods for agar diffusion disk tests are those recommended by
NCCLS.
[0131] The susceptibility breakpoints for azithromycin were defined
as follows:
17 Susceptible Intermediate Resistant Zone Zone Zone Pathogen MIC
Diameter MIC Diameter MIC Diameter Streptococcus .ltoreq.0.5
.gtoreq.18 1 14-17 .gtoreq.2 .ltoreq.13 H. influenzae .ltoreq.4
.gtoreq.12 * * * M. catarrhalis .ltoreq.2 .gtoreq.18 4 14-17
.gtoreq.8 .ltoreq.13
[0132] MIC (.mu.g/ml); Zone diameter (mm); *Current absence of data
on resistant strains precludes defining any resistant categories
other than "susceptible" for azithromycin.
[0133] 2.3.2 Human Studies: Otitis Media Studies
[0134] 5 2.3.2.1 Study A0661015
[0135] This was a non-comparative trial using a single 30 mg/kg
dose of azithromycin in the treatment of otitis media in pediatric
subjects undergoing diagnostic tympanocentesis. Overall the MITT
analysis of bacteriological response included 113 subjects.
Thirty-nine strains of H. influenzae were able to be evaluated for
bacteriologic outcome and were susceptible as defined by NCCLS
criteria. The clinical failure (and presumed persistence) rate was
33.3%. Historically, H. influenzae as the causative pathogen in
otitis media has been difficult to treat as evidenced by the
clinical cure rates in package inserts for other antibiotics (see
Table below). The latter is true for multiple antibiotics, despite
the organism being susceptible to the antibiotic. Not all strains
are equally virulent and the growth rate and kinetics of infection
may influence the outcome. In addition, H. influenzae has been a
difficult organism to culture from the middle ear. The use of PCR
primers specific for this organism (and others) has been shown to
have detection limits equivalent to 6-7 organisms and to be 85%
concordant with traditional culture methods with no false
positives. The protocol was further validated by using reverse
transcriptase-polymerase chain reaction to detect the presence of
bacterial mRNA in a significant percentage of culturally sterile
middle ear effusions, thereby establishing the presence of viable,
metabolically active, intact organisms in patients with otitis
media with effusion that are culture-negative. Using this
methodology, seventeen additional patients were identified as
having an H. influenzae strain at baseline by PCR analysis; all
were deemed clinically cured at the test of cure (TOC) end point.
If these H. influenzae cures are added into the total, the clinical
cure rate increases to 76.8% overall.
18 H. influenzae Historical Response Rates to Other Antibiotics
Primary Antibiotic Response Comparator Response Endpoint
Azithromycin 28/44 (64%) N/A N/A Clinical cure at TOC (1015) visit
(day 24-28) Azithromycin 30/47 (64%) N/A N/A Presumptive
(historical) bacterial/clinical cure outcomes (i.e., clinical
success) at day 30 Cefpodoxime 50/76 (66%) Cefixime 61/81 (75%)
Presumptive proxetil bacterial/clinical success outcomes (i.e.,
cured and improved) at 4-21 day post-therapy follow-up
Clarithromycin 10/14 (71%) Oral 3/4 (75%) Presumptive Cephalosporin
bacterial/clinical eradication/clinical cure outcomes (i.e.,
clinical success) post-therapy Ceftriaxone 22/31 (71%) N/A N/A
Bacteriological eradication rates at study day 30 + 2 Cefprozil 17%
less than control (amoxicillin/clavulanic Presumptive acid)
cefprozil success rate bacterial/clinical cure outcomes (i.e.,
clinical success) at 10-16 days post-therapy Source: Data herein
and 2000 Physicians' Desk Reference; N/A = Not Applicable
[0136] All M. catarrhalis (10 isolates) were susceptible to
azithromycin and clinically cured at TOC.
[0137] For pneumococcal isolates for which MIC values were
determined, the clinical cure rate versus susceptible S. pneumoniae
isolates (MICs.ltoreq.0.25 .mu.g/ml) was 92.5% and 66.7% versus
resistant isolates. Of note, 40% of strains with MIC values of
>256 .mu.g/ml were clinically cured. The one failure that
occurred in the group of pneumococcal strains with an MIC of 8
.mu.g/ml was a patient that was coinfected with H. influenzae at
baseline. On day 4 a culture was taken from the opposite ear of
this patient, yielding a clonally distinct S. pneumoniae strain
with high level resistance to both azithromycin and clindamycin
(MIC>256 and >128 .mu.g/ml respectively; see below). The
evaluation of the left ear by the clinician at this time found that
ear pain and ear fullness decreased and there was increased hearing
in the left ear. In addition, the acoustic reflectometry on the
left ear had improved by day 4. Thus, it appeared that the ear with
initial S. pneumoniae isolate (MIC to azithromycin of 8 .mu.g/ml)
could be counted as clinically cured and that the H. influenzae
co-infection may also have been resolved. On the same day, this
patient was started on amoxicillin/clavulanic acid therapy;
however, this patient's response was assessed as a failure at both
EOT and TOC. It is likely that this failure resulted from
nonresolution of the pneumococcal isolate harboring erm(B) (see
below). If one corrects for this patient by ascribing the failure
to the >256 .mu.g/ml category, the cure rates become 7/7 for
strains with an efflux mechanism of resistance and 2/6 for strains
with a ribosome methylation mechanism of resistance. Although the
numbers are small and eradication is presumed, the cure rate
observed for strains harboring an efflux versus a methylase gene
agrees with observations made in recent publications.
[0138] PCR determination of resistance mechanism in all the
azithromycin-resistant pneumococci was done by previously published
methods. All the strains with an azithromycin MIC of >256
.mu.g/ml and a clindamycin MIC of 128 or >256 .mu.g/ml had the
erm(B) resistance determinant. All strains with an azithromycin MIC
of 8 .mu.g/ml and a clindamycin MIC of .ltoreq.0.06 .mu.g/ml were
confirmed as mef(A). Other resistance mechanisms such as esterases
[(ere(A), ere(B)], phosphotransferases [mph(A), mph(B), mph(C)] or
other erm classes [erm(A)--including erm(TR) subclass, erm(C)] were
not detected. Mutations in 23S rRNA or ribosomal proteins L4 and
L22 were not determined.
[0139] The one patient mentioned above that harbored a strain with
the efflux determinant at day 1 was a clinical failure at TOC.
However, the failure appears to be the result of infection and
survival by another S. pneumoniae isolate. When the isolates,
0067-base and -67-Ubase.1 (day 4), were examined by pulse-field gel
electrophoresis, they were found to be clonally distinct.
Additionally, the initial S. pneumoniae isolate, 0067-base, was
mef(A) by PCR analysis, while the second isolate, 0067-Ubase. 1,
was an isolate from the opposite ear and contained a different S.
pneumoniae isolate with an erm(B) determinant.
[0140] The agreement in susceptibility interpretation, MIC versus
Zone Size, was 100% for all species isolated. That is, a strain
having a resistant MIC always had a resistant Zone Size and the
same was true for susceptible strains. No intermediate values were
observed. This data is consistent with the current breakpoints for
zone size and correlates well with MIC values. Given the recent
discussions around the lack of correlation between clinical cures
and in vitro susceptibility breakpoints, it would seem prudent to
consider that seven of the seven pneumococci harboring mef(A) at
baseline were clinical cures by TOC. All of these isolates had an
azithromycin MIC of 8 .mu.g/ml.
[0141] 2.3.2.2 Study 95-001
[0142] In this study, both a single dose (30 mg/kg) and 3-day
regimen of azithromycin (10 mg/kg/day for 3 days) were compared to
a single intramuscular dose of ceftriaxone (50 mg/kg). Specimens
for culture and susceptibility testing were obtained from the
infected ear by tympanocentesis within 24 h of start of therapy.
Susceptibility to azithromycin and ceftriaxone was evaluated by
Kirby-Bauer disk diffusion assays following the 1993 NCCLS
guidelines. However, the study was evaluated using the breakpoints
in the most recent set of guidelines.
[0143] To be a bacteriological cure, the MITT subject had to have a
positive culture from the middle ear for S. pneumoniae, H
influenzae, or M. catarrhalis. Eradication was defined as presumed
eradication of pretreatment pathogen(s) based on signs/symptoms or
unavailability of culturable material. All evaluable patients had
only one of the bacterial species present at baseline. There was no
bacteriological response data collected for 95-001. However, the
clinical outcome by bacterial pathogen at follow-up (approximately
28 days after first visit) was collected. For patients with S.
pneumoniae as the baseline pathogen, all treatment arms yielded
100% clinical cure when the investigators' evaluations that were
missing are not included in the analysis. There were few M
catarrhalis strains isolated for any treatment arm but the two
isolates observed in the 3-day dosing regimen of azithromycin were
presumed bacteriological cures at follow-up. In otitis media caused
by H. influenzae, there was 1 failure in 8 patients and 2 failures
in 13 patients in the single dose and 3-day regimens of
azithromycin, respectively. The comparator drug, ceftriaxone, had
no failures out of 9 patients.
[0144] All H. influenzae organisms isolated were susceptible to
azithromycin by agar diffusion (zone size), giving zone sizes of
.gtoreq.19 mm with azithromycin and therefore susceptible according
to the NCCLS breakpoint of .gtoreq.12 mm. Approximately 80% of the
S. pneumoniae isolates were susceptible by MIC analysis whereas
15.7% of the strains had intermediate resistance and 3.5% were
fully resistant. Of the nine patients with S. pneumoniae isolates
with intermediate resistance, five were in one of the azithromycin
regimens. All had clinical outcomes of either "cure" or
"improvement" at EOT or follow-up. Even the highly
macrolide-resistant isolate (MIC=256 .mu.g/ml) was assessed a
clinical cure at follow-up. Both dosing schedules of azithromycin
were equivalent to the comparator, ceftriaxone.
* * * * *