U.S. patent application number 14/557160 was filed with the patent office on 2015-03-26 for antimicrobial medical devices containing chlorhexidine free base and salt.
This patent application is currently assigned to THE TRUSTEES OF COLUMBIA UNIVERSITY IN THE CITY OF NEW YORK. The applicant listed for this patent is THE TRUSTEES OF COLUMBIA UNIVERSITY IN THE CITY OF NEW YORK. Invention is credited to Shanta M. Modak, Lester A. Sampath.
Application Number | 20150087716 14/557160 |
Document ID | / |
Family ID | 25001831 |
Filed Date | 2015-03-26 |
United States Patent
Application |
20150087716 |
Kind Code |
A1 |
Modak; Shanta M. ; et
al. |
March 26, 2015 |
ANTIMICROBIAL MEDICAL DEVICES CONTAINING CHLORHEXIDINE FREE BASE
AND SALT
Abstract
The present disclosure invention relates to medical devices
treated with a solution comprising one or more solvents and a
combination of chlorhexidine free base and a water-soluble
chlorhexidine salt in a weight/weight ratio of between about 1:1 to
about 1:5, preferably about 1:1.
Inventors: |
Modak; Shanta M.; (River
Edge, NJ) ; Sampath; Lester A.; (Nyack, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
THE TRUSTEES OF COLUMBIA UNIVERSITY IN THE CITY OF NEW
YORK |
New York |
NY |
US |
|
|
Assignee: |
THE TRUSTEES OF COLUMBIA UNIVERSITY
IN THE CITY OF NEW YORK
New York
NY
|
Family ID: |
25001831 |
Appl. No.: |
14/557160 |
Filed: |
December 1, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13758686 |
Feb 4, 2013 |
8906401 |
|
|
14557160 |
|
|
|
|
11946622 |
Nov 28, 2007 |
8383143 |
|
|
13758686 |
|
|
|
|
09746670 |
Dec 22, 2000 |
7329412 |
|
|
11946622 |
|
|
|
|
Current U.S.
Class: |
514/635 |
Current CPC
Class: |
A61L 2300/404 20130101;
A61K 9/7023 20130101; A61L 15/44 20130101; A61K 31/155 20130101;
A61L 2300/206 20130101; A61L 29/16 20130101; A61K 47/32 20130101;
A61L 31/16 20130101; A61L 27/54 20130101 |
Class at
Publication: |
514/635 |
International
Class: |
A61K 9/70 20060101
A61K009/70; A61K 47/32 20060101 A61K047/32; A61K 31/155 20060101
A61K031/155 |
Claims
1. An antimicrobial medical article prepared by treating a
hydrophobic polymeric medical article, for an effective period of
time, with a solution consisting essentially of one or more
solvents and a mixture of chlorhexidine free base and a
water-soluble chlorhexidine salt, wherein the weight/weight ratio
of chlorhexidine free base and the water-soluble chlorhexidine salt
in the solution is between 1:1 to 1:5.
2. The antimicrobial medical article of claim 1, wherein the
article is expanded polytetrafluoroethylene.
3. The antimicrobial medical article of claim 1, wherein the
article is a polytetrafluoroethylene soft tissue patch.
4. A method of preparing a medical article comprising the steps of:
(i) placing the medical article in a solution consisting
essentially of (a) a solvent selected from the group consisting of
water, reagent alcohol, tetrahydrofuran, dimethylsulfoxide,
dimethylformamide, N-methyl-2-pyrrolidone, and mixtures thereof;
and (b) a mixture of chlorhexidine free base and a water-soluble
chlorhexidine salt, wherein the weight/weight ratio of
chlorhexidine free base and water-soluble chlorhexidine salt in the
solution is between 1:1 to 1:5; (ii) soaking the medical article in
the solution for an effective period of time to allow the medical
article to swell; (iii) removing the medical article from the
solution; and (iv) drying the medical article.
5. The method of claim 4, wherein the medical article is a
hydrophobic polymeric medical article.
6. The method of claim 5, wherein the hydrophobic polymeric medical
article is selected from the group consisting of expanded
polytetrafluoroethylene and a polytetrafluoroethylene soft tissue
patch.
7. An antimicrobial medical article prepared by treating a medical
article, for an effective period of time, with a solution
comprising a solvent and an antimicrobial mixture consisting
essentially of chlorhexidine free base and a water-soluble
chlorhexidine salt, wherein the molar ratio of chlorhexidine free
base and the water-soluble chlorhexidine salt in the solution is
between 1:1 and 1:5.
8. The antimicrobial medical article of claim 7, wherein the
article is a catheter.
9. The antimicrobial medical article of claim 7, wherein the
article is a hydrophobic polymeric medical article.
10. The antimicrobial medical article of claim 9, wherein the
hydrophobic polymeric medical article is selected from the group
consisting of expanded polytetrafluoroethylene and a
polytetrafluoroethylene soft tissue patch.
Description
1.0 CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/758,686 filed Feb. 4, 2013, which is a
continuation of U.S. patent application Ser. No. 11/946,622, filed
Nov. 28, 2007, which issued as U.S. Pat. No. 8,383,143, which is a
divisional of U.S. patent application Ser. No. 09/746,670, filed
Dec. 22, 2000, which issued as U.S. Pat. No. 7,329,412, the
contents of each of which are incorporated herein by reference in
their entireties, and to each of which priority is claimed.
2.0 INTRODUCTION
[0002] The present invention relates to medical devices treated
with a solution comprising a combination of chlorhexidine free base
and a water-soluble chlorhexidine salt, in a ratio that facilitates
chlorhexidine uptake by the devices and hence improves
antimicrobial effectiveness.
3.0 BACKGROUND OF THE INVENTION
[0003] Whenever a medical device comes in contact with a patient, a
risk of infection is created. Thus, a contaminated examination
glove, tongue depressor, or stethoscope could transmit infection.
The risk of infection dramatically increases for invasive medical
devices, such as intravenous catheters, arterial grafts,
intrathecal or intracerebral shunts and prosthetic devices, which
not only are, themselves, in intimate contact with body tissues and
fluids, but also create a portal of entry for pathogens.
[0004] Catheter related infections, especially blood stream
infections, are associated with increased morbidity (10 to 20
percent), prolonged hospitalization (by a period having a mean of
seven days), and increased medical costs (approximately $6,000 per
hospitalization). According to a survey of intensive care units
from 1986 through 1990 by the National Nosocomial Infection
Surveillance System, the rate of catheter-related blood stream
infections ranged from 2.1 to 30.2 per 1,000 catheter-days.
Infections associated with central venous catheters have been
reported to result from the transcutaneous migration of the
pathogens from the insertion site with the eventual colonization of
the catheter tip. In addition, intraluminal colonization has been
suggested to result from contaminated hubs and infusates that
contribute to catheter related blood stream infections. The longer
the duration of catheterization, the greater the susceptibility to
either luminal or outer surface colonization of catheters. Even for
short term use of catheters, infections have been reported due to
contamination of the insertion sites.
[0005] A number of methods for reducing the risk of infection have
been developed which incorporate anti-infective agents into medical
devices. Such devices desirably provide effective levels of
anti-infective agent during the period that the device is being
used. Sustained release may be problematic to achieve, in that a
mechanism for dispensing anti-infective agent over a prolonged
period of time may be required, and the incorporation of sufficient
amounts of anti-infective agent may adversely affect the surface
characteristics of the device. The difficulties encountered in
providing effective antimicrobial protection increase with the
development of drug-resistant pathogens.
[0006] One potential solution to these problems is the use of a
synergistic combination of anti-infective agents that requires
relatively low concentrations of individual anti-infective agents
which may have differing patterns of bioavailability. For example,
WO 97/25085 relates to medical devices comprising synergistic
combinations of chlorhexidine and triclosan. U.S. Pat. Nos.
5,616,338 and 5,019,096 relate to infection resistant medical
devices comprising synergistic combinations of a silver salt, a
biguanide (such as chlorhexidine) and a polymeric component that
forms a matrix to provide a sustained release of the silver salt
and biguanide.
[0007] U.S. Pat. Nos. 5,165,952 and 5,451,424 relate to medical
articles with chlorhexidine both coated on and bulk distributed
throughout the medical articles. When chlorhexidine is bulk
distributed it adversely affects certain characteristics of the
device such as tensile strength, and the high temperatures needed
for extension of plastics such as polyurethane may damage the
chlorhexidine.
[0008] U.S. Pat. No. 5,089,205 relates to incorporation of
chlorhexidine free base or one of its salts in a medical device
such as a glove by both a distribution or dipping process.
[0009] Chlorhexidine is a broad spectrum antimicrobial agent and
has been used as an antiseptic for several decades with minimal
risk of developing resistant microbes. When relatively soluble
chlorhexidine salts, such as chlorhexidine acetate, were used to
impregnate catheters, the release was undesirably rapid. The
duration of the antimicrobial efficacy of medical devices
impregnated with chlorhexidine salts, such as chlorhexidine
acetate, is short lived. Chlorhexidine free base is not soluble in
water or alcohol and cannot be impregnated in sufficient amounts
because of low solubility in a solvent system.
[0010] In contrast to the present invention, none of the
above-cited references teach medical articles treated with a
solution comprising a combination of chlorhexidine free base and a
water-soluble chlorhexidine salt, at particular ratios, which
provide improved antimicrobial effectiveness through an increased
uptake of chlorhexidine into the medical device, increased
retention of chlorhexidine in the medical device and prolonged
release of chlorhexidine from the medical device, while utilizing
relatively low levels of chlorhexidine.
4.0 SUMMARY OF THE INVENTION
[0011] The present invention relates to medical devices treated
with a solution comprising one or more solvents and a combination
of chlorhexidine free base and a water-soluble chlorhexidine salt,
in a weight/weight ratio of between about 1:1 to about 1:5
(inclusive), preferably about 1:1 of chlorhexidine free base to
chlorhexidine salt. The invention further relates to methods of
preparing medical devices by exposing them, in whole or in part, to
a solution comprising one or more solvents and the above-recited
combinations of chlorhexidine free base and chlorhexidine salt.
[0012] This invention is based, at least in part, on the discovery
that devices treated with combinations of chlorhexidine free base
and a water-soluble chlorhexidine salt exhibit improved
antimicrobial effectiveness due to increased uptake of
chlorhexidine into the medical device, increased retention of
chlorhexidine in the medical device, and prolonged release of
chlorhexidine while utilizing relatively low levels of
chlorhexidine, and, in certain non-limiting embodiments, in the
absence of agents other than chlorhexidine. In particular, while it
had been previously found that triclosan can be particularly useful
when used in conjunction with chlorhexidine free base, it has been
further discovered that medical articles having suitable
antimicrobial properties may be prepared, according to the present
invention, without the use of triclosan. Therefore, in particular
embodiments, medical articles according to the present invention
offer the advantage of preventing or inhibiting infection while
avoiding undesirable adverse reactions to antimicrobial agents
other than chlorhexidine by allergic individuals.
5.0 DETAILED DESCRIPTION OF THE INVENTION
[0013] The present invention provides for medical articles treated
with a solution comprising one or more solvents and a combination
of chlorhexidine free base ("CHX") and a water-soluble
chlorhexidine salt, and further provides for methods of preparing
medical devices by exposing the device, in whole or in part, to
said solution.
[0014] While not being bound or limited by any particular theory,
it is believed that the combination of CHX and water-soluble
chlorhexidine salt forms a soluble complex. This would explain the
increased uptake of chlorhexidine into the medical device,
increased retention of chlorhexidine in the medical device, and
increased sustained release of chlorhexidine from the medical
device while utilizing relatively low levels of chlorhexidine in
the absence of agents other than chlorhexidine. The following are
definitions of terms used herein unless otherwise indicated:
[0015] Water soluble chlorhexidine salts have a solubility of at
least about 2.0 grams per 100 ml in water at 20.degree. C. Examples
of water soluble chlorhexidine salts include chlorhexidine
diacetate (also referred to herein as chlorhexidine acetate, or
"CHA") and chlorhexidine digluconate (or "CHG") with CHA being
preferred.
[0016] The terms "medical article" and "medical device" are used
interchangeably herein. Medical articles that may be treated
according to the invention are either fabricated from and/or coated
or treated with biomedical polymer (and hence may be referred to as
"polymeric medical articles") and include, but are not limited to,
catheters including urinary catheters and vascular catheters (e.g.,
peripheral and central vascular catheters), wound drainage tubes,
arterial grafts, soft tissue patches (such as
polytetrafluoroethylene (PTFE) soft tissue patches), gloves,
condoms, shunts, stents, tracheal catheters, wound dressings,
sutures, guide wires and prosthetic devices (e.g., heart valves and
LVADs). Vascular catheters which may be prepared according to the
present invention include, but are not limited to, single and
multiple lumen central venous catheters, peripherally inserted
central venous catheters, emergency infusion catheters,
percutaneous sheath introducer systems and thermodilution
catheters, including the hubs and ports of such vascular catheters.
The present invention may be further applied to medical articles
that have been prepared according to U.S. Pat. Nos. 5,616,338 and
5,019,096 by Fox, Jr. et al. and U.S. Pat. No. 5,772,640 by Modak
et al.
[0017] The term "hydrophilic polymeric medical article" is a
medical article fabricated from a hydrophilic polymer. As used
herein, "hydrophilic polymer" refers to polymers that have a water
absorption greater than 0.6 percent by weight (and, in preferred
embodiments, less than 2 percent by weight; as measured by a 24
hour immersion in distilled water, as described in AS.TM.
Designation D570-81) including, but not limited to biomedical
polyurethanes (e.g., ether-based polyurethanes and ester-based
polyurethanes, as set forth in Baker, 1987, in Controlled Release
of Biologically Active Agents, John Wiley and Sons, pp. 175-177 and
Lelah and Cooper, 1986, Polyurethanes in Medicine, CRC Press, Inc.,
Fla. pp. 57-67; polyurethanes comprising substantially aliphatic
backbones such as Tecoflex.TM. 93A; polyurethanes comprising
substantially aromatic backbones such as Tecothane.TM.; and
Pellethane.TM.), polylactic acid, polyglycolic acid, natural rubber
latex, and gauze or water-absorbent fabric, including cotton gauze
and silk suture material.
[0018] The term "hydrophobic polymeric medical article" is a
medical article fabricated from a hydrophobic polymer. As used
herein, "hydrophobic polymer" refers to a polymer that has a water
absorption of less than 0.6% (w/w) and includes, but is not limited
to, silicone polymers such as biomedical silicones (e.g., Silastic
Type A) or elastomers (e.g., as set forth in Baker, 1987, in
Controlled Release of Biologically Active Agents, John Wiley and
Sons, pp. 156-162), Dacron, PTFE (also "Teflon"), expanded PTFE,
polyvinyl chloride (PVC), cellulose acetate, polycarbonate, and
copolymers such as silicone-polyurethane copolymers (e.g., PTUE 203
and PTUE 205 polyurethane-silicone interpenetrating polymer).
[0019] The terms "treat", "treated", "treating", etc., as used
herein, refer to coating, impregnating, or coating and impregnating
a medical article with anti-infective agent. Medical articles are
"treated" by exposing them, for an effective period of time, to a
treatment solution, where an "effective period of time" is that
period of time sufficient to introduce anti-infective qualities of
the anti-infective agent to the articles. Medical articles may be
dipped, soaked, or otherwise have a surface coated. The term
"dipped" suggests briefer exposure to the treatment solution
relative to "soaking," and preferably is for a period of time less
than fifteen minutes.
[0020] Percentages recited herein refer to weight/volume (w/v),
except as indicated otherwise (e.g., volume/volume or "v/v").
[0021] The term "CFU" means colony forming unit.
[0022] The term "about" indicates a variation within 20
percent.
[0023] The present invention provides for medical articles treated
with a solution comprising one or more solvents and a combination
of CHX and a water-soluble chlorhexidine salt, in a weight/weight
ratio of between about 1:1 and 1:5, preferably about 1:1. Such
medical articles include hydrophilic polymeric medical articles as
well as hydrophobic polymeric medical articles fabricated from
and/or coated or treated with such a biomedical polymer. In
addition, the present invention may be applied to medical articles
that have been prepared according to U.S. Pat. Nos. 5,616,338 and
5,019,096 by Fox, Jr. et al. and U.S. Pat. No. 5,772,640 by Modak
et al. Such one or more solvents may be selected from the group
consisting of water, reagent alcohol, and tetrahydrofuran ("THF"),
dimethylsulfoxide, dimethylformamide, N-methyl-2-pyrrolidone, and
mixtures thereof.
[0024] In a specific non-limiting embodiment, the treatment
solution comprises CHX-CHA in a weight/weight ratio between about
1:1 and about 1:5, preferably about 1:1 of CHX to CHA.
[0025] The present invention further provides, in a non-limiting
embodiment, for methods of preparing medical devices by treating
the device, in whole or in part, with a solution comprising one or
more solvents and a complex formed by synergistic combinations of
chlorhexidine free base and chlorhexidine acetate.
[0026] In non-limiting embodiments, medical articles may be treated
with a solution comprising the steps of (i) placing the medical
article in a solution comprising (a) a solvent selected from the
group consisting of water, reagent alcohol, THF, dimethylsulfoxide,
dimethylformamide, N-methyl-2-pyrrolidone, and mixtures thereof and
(b) a mixture of CHX and a water-soluble chlorhexidine salt,
preferably CHA, preferably in a weight/weight ratio of between
about 1:1 and about 1:5; (ii) soaking the medical article in the
solution for an effective period of time to allow the medical
article to swell and to incorporate the anti-infective agents;
(iii) removing the medical article from the solution; and (iv)
drying the medical article.
[0027] Medical articles prepared according to the invention may be
treated on an external surface, internal surface, or both. For
example, and not by way of limitation, where the medical article is
a catheter having a lumen, the internal (i.e., luminal) surface
and/or external surface of the catheter may be treated together or
separately according to the invention. An open-ended catheter may
be placed in a treatment solution such that the internal and
external surfaces are exposed to the treatment solution.
Alternatively, the ends of the catheter may be sealed before being
placed in the treatment solution so that only the external surface
is exposed to the treatment solution. Alternatively, only the
internal surface may be exposed to the treatment solution if the
solution is pushed, pulled or allowed to pass through and/or fill
the lumen without immersing the catheter in the treatment
solution.
[0028] In specific non-limiting embodiments, a catheter having a
lumen may be treated with a solution comprising the steps of (i)
exposing the lumen of the catheter to a solution comprising (a) a
solvent selected from the group consisting of water, alcohol, THF,
dimethylsulfoxide, dimethylformamide, N-methyl-2-pyrrolidone, and
mixtures thereof and (b) a mixture of CHX and a water-soluble
chlorhexidine salt, preferably CHA, preferably in a molar ratio of
between about 1:1 and about 1:5; (ii) filling the lumen of the
catheter with the solution by pushing, pulling, or allowing passage
of the solution into the lumen for an effective period of time to
allow the material surrounding the lumen of the catheter to swell
and to incorporate the chlorhexidine; (iii) removing the solution
from the lumen of the catheter; and (iv) drying the catheter.
[0029] In the foregoing methods, the duration of exposure of the
medical article or portion thereof to the treatment solution may
preferably, but not by limitation, be ten seconds to one hour. The
duration of exposure of the lumen of a catheter may preferably, but
not by limitation, be ten seconds to two minutes. Longer periods of
exposure may be used provided that undesirable deterioration of the
medical article does not occur.
[0030] The treatment solutions may optionally further comprise (i)
an organic acid, at a concentration of between about 0.1 and about
5 percent, preferably between about 0.1 and about 2 percent; (ii)
an anti-inflammatory agent, at a concentration of between about 0.1
and about 5 percent, preferably between about 0.1 and about 1
percent; and/or (iii) a hydrogel at a concentration of between
about 0.5 to about 10 percent, preferably between about 1 and about
5 percent.
6.0 Working Examples
[0031] The following methods were used in performing experiments
discussed in the following examples, unless indicated
otherwise:
[0032] Method of Treatment of a Medical Article with Solution. The
medical article was treated by exposing the entire medical article,
or a portion thereof, to a solution containing CHA alone, CHX alone
or the CHX-CHA combination in various amounts in a solvent system.
The medical article, or a portion thereof, was exposed by soaking
the article in the solution for 100 seconds before removing the
article from the solution. For articles, such as catheters, having
an internal lumen, the solution was pushed into the lumen and
allowed to remain for 100 seconds before removal.
[0033] Method of Determining Drug Uptake. The amount of drug uptake
into the treated polymeric medical articles was determined using a
spectrophotometric method after extraction in alcohol.
[0034] Method of Determining Long Term Antimicrobial Efficacy in
Catheter Lumen. In order to determine the duration of antimicrobial
efficacy in catheter lumens exposed to treatment solutions,
catheters were perfused for 7 days using the following continuous
perfusion model. The distal lumens of catheters were connected to a
peristaltic pump in a closed loop, wherein 1.5 L of 10% (v/v)
trypticase soy broth in saline was constantly perfused by recycling
it through each catheter lumen at a rate of 83 ml/hr for 7 days. On
the eighth day the catheters were disconnected and used for
evaluation of bacterial adherence.
[0035] Method of Evaluating Microbial Adherence to a Catheter
Lumen. After perfusion of catheters for 7 days as set forth above,
the distal lumens of each catheter were filled with a 10.sup.8
CFU/ml culture of bacteria or yeast. In the case of exposure to E.
aerogenes, P. aeruginosa and C. albicans, cultures containing
10.sup.6 CFU/ml were used. The ends of the catheters were heat
sealed and the catheters were incubated for 24 hours in an orbital
shaker at 37.degree. C. After 24 hours, the lock cultures were
collected from the lumen and subcultured after serial dilution
using agent inactivating media. The outer surface of the whole
catheter was sterilized by wiping the outer surface with an alcohol
swab. Thereafter, the lumens were flushed with 20 ml trypticase soy
broth to remove non-adherent bacteria. The body of the catheters
were subdivided into 2 cm segments, which were further cut into 2
mm subsegments. The subsegments were placed in 4.0 ml agent
inactivating media and sonicated in a 4.degree. C. water bath using
an Astrasan Sonicator (Model 9T) at 60 KHertz. Thereafter, 0.5 ml
of the extract was then subcultured on a trypticase soy agar plate
and incubated at 37.degree. C. for 24 hours. Colony counts were
then determined.
[0036] Method of Evaluating Bacterial Adherence to PTFE Soft Tissue
Patch Disks. Polytetrafluoroethylene (PTFE) disks were soaked and
agitated in 3.0 ml of media containing 50% (v/v) bovine adult serum
and 50% (v/v) trypticase soy broth. The media was changed on days
1, 2 and 4. On the fourth day, 10.sup.5 CFU/ml of bacteria was
added to the media. On the fifth day, the disks were removed,
rinsed and rolled on drug inactivating agar. The plates were then
incubated for 24 hours at 37.degree. C. Colony counts were
determined thereafter.
[0037] Method of Determining Zones of Inhibition. Zones of
inhibition were measured by seeding a specified amount of bacteria
onto a trypticase soy agar plate. Then, three units of a specified
amount of medical article were placed on the plate. The plates were
incubated at 37.degree. C. for 24 hours. The zones of inhibition
were then measured for Day 1. To measure the zones of inhibition on
Day 2 and subsequent days, the units of medical article were
transferred onto a fresh plate of similarly prepared agar,
incubated at 37.degree. C. for 24 hours and colony-free zones were
measured.
6.1 Example: Polyurethane Central Venous Catheters
[0038] Polyurethane central venous catheters, which are hydrophilic
polymeric medical articles, were separated into three otherwise
identical groups of catheters and separately treated with a
solution that either (i) contained no antimicrobial agents; (ii)
contained CHA alone, or (iii) contained a combination of CHX and
CHA ("CHX-CHA") in accordance with the present invention. In
particular, the luminal surfaces of the catheters were separately
treated with one of the following solutions:
[0039] (1) a solvent system of 80% (v/v) reagent alcohol and 20%
(v/v) THF with no antimicrobial agents;
[0040] (2) 2.4% CHA in a solvent system of 80% (v/v) reagent
alcohol and 20% (v/v) THF; and
[0041] (3) 1.2% CHX and 1.2% CHA in a solvent system of 80% (v/v)
reagent alcohol and 20% (v/v) THF.
[0042] The solution was exposed to the luminal surface of the
catheter by pushing the solution into the lumen and allowing the
solution to remain in the lumen for 100 seconds. Thereafter, the
solution was removed, and the distal lumens of the catheters were
connected to a peristaltic pump in a closed loop, wherein 1.5 L of
10% trypticase soy broth in saline was constantly perfused by
recycling it through each catheter lumen at a rate of 83 ml/hr for
7 days, according to the continuous perfusion method discussed
above. On the eighth day the catheters were disconnected and the
ability of bacteria to adhere to the lumens was tested as
follows.
[0043] The distal lumens of each of the three groups of catheters
were separately filled with 8.times.10.sup.8 CFU/ml culture of S.
epidermidis. The ends of the catheters were heat sealed and the
catheters were incubated for 24 hours in an orbital shaker at
37.degree. C. After 24 hours, the lock cultures were collected from
the lumen and subcultured after serial dilution using agent
inactivating media. The outer surface of the whole catheter was
sterilized by wiping the outer surface with an alcohol swab.
Thereafter, the lumens were flushed with 20 ml trypticase soy broth
to remove non-adherent bacteria. The bodies of the catheters were
subdivided into 2 cm segments, which were further cut into 2 mm
subsegments. The subsegments were placed in 4.0 ml agent
inactivating media and sonicated in a 4.degree. C. water bath using
an Astrasan Sonicator (Model 9T) at 60 KHertz. Thereafter, 0.5 ml
of the extract was then subcultured on a trypticase soy agar plate
and incubated at 37.degree. C. for 24 hours. Colony counts were
then determined and are shown below in Table 1.
TABLE-US-00001 TABLE 1 Bacterial Adherence of S. epidermidis
Solution (CFU/cm) 80% (v/v) reagent alcohol + 2.2 .times. 10.sup.4
20% (v/v) THF 2.4% CHA in 3 .times. 10.sup.2 80% (v/v) reagent
alcohol + 20% (v/v) THF 1.2% CHX + 2 1.2% CHA in 80% (v/v) reagent
alcohol + 20% (v/v) THF
[0044] The luminal surfaces of catheters were also tested according
to the above described techniques to evaluate the adherence of a
wide variety of organisms. The luminal surfaces of catheters were
separately treated with the following solutions:
[0045] (1) a solvent system of 80% (v/v) reagent alcohol and 20%
(v/v) THF with no antimicrobial agents; and
[0046] (2) 1.2% CHX and 1.2% CHA in a solvent system of 80% (v/v)
reagent alcohol and 20% (v/v) THF.
[0047] The luminal surfaces were exposed to the respective
solutions for 100 seconds. Thereafter, the solutions were removed,
and the lumens were perfused according to the continuous perfusion
method discussed above.
[0048] On the eighth day, the catheters were disconnected and
susceptibility to microbial adherence was evaluated. The distal
lumens of each group of catheters were separately filled with the
following amounts of bacteria (S. aureus, P. aeruginosa, and
Enterobacter) or yeast (C. albicans):
[0049] (1) 8.times.10.sup.8 CFU/ml culture of S. aureus;
[0050] (2) 8.times.10.sup.6 CFU/ml culture of P. aeruginosa;
[0051] (3) 8.times.10.sup.8 CFU/ml culture of Enterobacter; and
[0052] (4) 8.times.10.sup.6 CFU/ml culture of C. albicans.
The four subgroups of lumens were prepared for evaluating microbial
adherence to the catheter lumens as described above. The ends of
the catheters were heat sealed, incubated, subcultured, externally
sterilized, flushed, subdivided, placed in inactivating media and
sonicated according to the techniques set forth supra. Thereafter,
0.5 ml of the extract was subcultured, incubated and examined to
determine the colony counts. The results are shown below in Table
2.
TABLE-US-00002 TABLE 2 Adherence Adherence of of Adherence of
Adherence of S. aureus P. aeruginosa Enterobacter C. albicans
Solution (CFU/cm) (CFU/cm) (CFU/cm) (CFU/cm) 80% (v/v) 1.3 .times.
10.sup.4 >10.sup.5 >10.sup.5 1.7 .times. 10.sup.4 reagent
alcohol + 20% (v/v) THF 1.2% CHX + 3 9 2 26 1.2% CHA in 80% (v/v)
reagent alcohol + 20% (v/v) THF
[0053] The results shown in Table 1 demonstrate the synergistic
antimicrobial effect of treating a polyurethane central venous
catheter lumen with a solution comprising the mixture of CHX and
CHA. Table 2 shows that articles treated with CHX and CHA exhibit
an increased effectiveness across a wide variety of organisms by
decreasing luminal adherence substantially more than articles
treated with no antimicrobial agents.
[0054] In a further study, the luminal surface of three groups of
otherwise identical polyurethane central venous catheters were
separately treated with one of the following three solutions:
[0055] (1) 2% CHA in a solvent system of 80% (v/v) ethanol and 20%
(v/v) THF;
[0056] (2) 0.625% CHX and 1.375% CHA in a solvent system of 80%
(v/v) ethanol plus 20% (v/v) THF; and
[0057] (3) 1% CHX and 1% CHA in a solvent system of 80% (v/v)
ethanol plus 20% (v/v) THF.
[0058] The solution was pushed into the lumen and allowed to remain
for 100 seconds.
[0059] The amount of uptake of chlorhexidine in the catheters was
determined using a spectrophotometric method after extraction with
alcohol.
[0060] In order to determine the amount of drug retention and
antimicrobial efficacy, the catheters were perfused for 6 days with
1.500 L of saline per day. The treated catheters were then studied
on Day 1 and Day 6 after perfusion to determine the amount of drug
retention. The chlorhexidine in the catheter after perfusion was
determined using a spectrophotometric method after extraction with
alcohol. The antibacterial activity was measured on Day 6 after
perfusion by counting the CFU/cm of S. epidermidis. Table 3 shows
results of the uptake, drug retention and antibacterial activity of
the treated catheters.
TABLE-US-00003 TABLE 3 Retention Antibacterial of Drug Activity
(CFU/cm) Uptake (.mu.g/cm) S. epidermidis Solution (.mu.g/cm) Day 1
Day 6 Day 6 2% CHA in 44 34 8 10.sup.2 80% (v/v) Ethanol + 20%
(v/v) THF 0.625% CHX + 70 43 22 0 1.375% CHA in 80% (v/v) Ethanol +
20% (v/v) THF 1% CHX + 80 45 26 0 1% CHA in 80% (v/v) Ethanol + 20%
(v/v) THE
[0061] These results demonstrate the synergistic antimicrobial
effect of treating a polyurethane central venous catheter lumen
with a solution comprising a mixture of CHX and CHA.
6.2 Example: Urinary Catheters
[0062] Hydrophilic urinary catheters were separated into two
otherwise identical groups, and the whole catheters (i.e., external
and luminal surfaces of the catheter) were treated with a solution
containing either:
[0063] (1) 4% CHA in a solvent system of 85% (v/v) THF and 15%
(v/v) methanol; or
[0064] (2) 2% CHX plus 2% CHA in a solvent system of 85% (v/v) THF
and 15% (v/v) methanol. [0065] The catheters of each group were
soaked in the respective solution for 30 minutes to one hour.
Thereafter, the catheters were removed from the solution.
[0066] The amount of uptake of chlorhexidine was determined using a
spectrophotometric method after extraction with alcohol, which
results are shown below in Table 4.
[0067] The two groups of catheters were separately exposed to
cultures of P. aeruginosa and C. albicans in order to study the
antimicrobial efficacy of the medical article. Trypticase soy agar
plates were seeded with 0.3 ml of 10.sup.8 CFU/ml of P. aeruginosa
and C. albicans, respectively. Thereafter, a 0.5 cm length of
urinary catheter was placed on each plate with three units per
plate. The plates were then incubated for 24 hours at 37.degree. C.
After 24 hours, the zones of inhibition were measured for Day 1. To
measure the zones of inhibition for Day 2 to Day 6, the process was
repeated upon transferring the units to fresh agar plates similarly
prepared. The results are shown in Table 4.
TABLE-US-00004 TABLE 4 Antimicrobial Efficacy Antimicrobial
Efficacy (Zone of Inhibition (Zone of Inhibition (mm)) (mm)) P.
aeruginosa C. albicans Uptake Day Day Solution (.mu.g/cm) 1 2 3 4 5
6 1 2 3 4 5 6 4% CHA in 123 15 11 10 9 0 0 11 9 0 0 0 0 85% (v/v)
THF + 15% (v/v) Methanol 2% CHX + 380 16 13 11 10 10 10 12 11 11 10
9 6 2% CHA in 85% (v/v) THF + 15% (v/v) Methanol
[0068] These results demonstrate the synergistic antimicrobial
effect of treating the urinary catheters with a solution comprising
a mixture of CHX and CHA.
6.3 Example: PTFE Soft Tissue Patches
[0069] Disks cut from PTFE soft tissue patches, which are
hydrophobic polymeric medical articles, were treated with a
solution that contained CHA alone and a solution that contained a
CHX-CHA complex in accordance with the present invention. Groups of
disks having a 1 mm thickness were treated for one hour with one of
the following solutions:
[0070] (1) 0.4% CHA in a solvent system of 70% (v/v) THF and 30%
(v/v) methanol; or
[0071] (2) 0.2% CHX and 0.2% CHA in a solvent system of 70% (v/v)
THF and 30% (v/v) methanol.
[0072] The amount of uptake of chlorhexidine in the PTFE disks was
determined using a spectrophotometric method after extraction with
alcohol, and the results are shown below in Table 5.
[0073] The two groups of disks were separately exposed to cultures
of P. aeruginosa and S. epidermidis in order to study their
antimicrobial efficacy. Trypticase soy agar plates were seeded with
0.3 ml of 10.sup.8 CFU/ml of P. aeruginosa and C. albicans,
respectively. Thereafter, 0.5 cm diameter disks were placed on each
plate with three units per plate. The plates were then incubated
for 24 hours at 37.degree. C. After 24 hours, the zones of
inhibition were measured for Day 1. The process was repeated upon
transferring the disks to fresh agar plates similarly prepared for
Day 2 to Day 6. The zones of inhibition are shown in Table 5.
TABLE-US-00005 TABLE 5 Antimicrobial Efficacy Antimicrobial (Zone
of Inhibition Efficacy (Zone of (mm)) Inhibition (mm)) P.
aeruginosa S. epidermidis Uptake Day Day Solution (.mu.g/cm) 1 2 3
4 1 2 3 4 0.4% CHA in 450 8 5 0 0 12 10 9 9 70% (v/v) THF + 30%
(v/v) Methanol 0.2% CHX + 840 12 8 8 7 15 13 12 11 0.2% CHA in 70%
(v/v) THE + 30% (v/v) Methanol
[0074] These results demonstrate the synergistic effect of treating
PTFE soft tissue patches with a solution comprising a mixture of
CHX and CHA.
[0075] Bacterial adherence on PTFE soft tissue patch disks treated
with CHA alone, CHX alone, or a mixture of CHA and CHX were
studied. 2 mm thick disks were separated into four groups and
separately treated with one of the following solutions:
[0076] (1) a solvent system of 70% (v/v) THF and 30% (v/v) methanol
with no antimicrobial;
[0077] (2) 0.4% CHA in a solvent system of 70% (v/v) THF and 30%
(v/v) methanol;
[0078] (3) 0.4% CHX in a solvent system of 70% (v/v) THF and 30%
(v/v) methanol; and
[0079] (4) 0.2% CHX and 0.2% CHA in a solvent system of 70% (v/v)
THF and 30% (v/v) methanol.
[0080] In order to determine the bacterial adherence to the PTFE,
three disks of 1 cm diameter from patches in each treatment group
were soaked and agitated in 3.0 ml of media containing 50% (v/v)
bovine adult serum and 50% (v/v) trypticase soy broth. The media
was changed on days 1, 2 and 4. On the fourth day, 10.sup.5 CFU/ml
of S. aureus was added to the media. On the fifth day after
agitation in media, the disks were removed, rinsed and rolled on to
plates of drug inactivation agar. The plates were then incubated
for 24 hours at 37.degree. C. Thereafter, the colony counts were
determined, and the amount of antimicrobial present in the disks
was determined by extracting the antimicrobial from the disk with
alcohol, followed by spectrophotometric measurement. The results
are shown in Table 6.
TABLE-US-00006 TABLE 6 Bacterial Adherence of Drug levels S. aureus
(CFU/cm) Solution (.mu.g/disk) Day 5 70% (v/v) THF + 0 >10.sup.5
30% (v/v) methanol 0.4% CHA in 264 8 .times. 10.sup.2 70% (v/v) THF
+ 30% (v/v) methanol 0.4% CHX in 361 1 .times. 10.sup.2 70% (v/v)
THF + 30% (v/v) methanol 0.2% CHA + 360 60 0.2% CHX in 70% (v/v)
THF + 30% (v/v) methanol
[0081] These results demonstrate the synergistic effect of treating
PTFE soft tissue patches with a solution comprising a mixture of
CHX and CHA.
[0082] Various publications are cited herein, which are hereby
incorporated by reference in their entireties.
* * * * *