U.S. patent application number 11/614882 was filed with the patent office on 2007-05-10 for stabilized and lyophilized radiopharmaceutical agents.
Invention is credited to John H. Kuperus, RobertG JR. McKenzie, Brooke III Schumm.
Application Number | 20070104646 11/614882 |
Document ID | / |
Family ID | 35447603 |
Filed Date | 2007-05-10 |
United States Patent
Application |
20070104646 |
Kind Code |
A1 |
Kuperus; John H. ; et
al. |
May 10, 2007 |
STABILIZED AND LYOPHILIZED RADIOPHARMACEUTICAL AGENTS
Abstract
A novel method is set out of preparation of radioactive
diagnostic radiopharmaceutical in a stable, shippable, lyophilized
form by an apparatus designed to rapidly flash freeze and dehydrate
a radiopharmaceutical composition to minimize auto radiolysis. The
method proposes rapid cooling and removal of ambient vapor, and
then ultra cold removal when the potential of explosive liquid
oxygen is eliminated. The radioactive diagnostic
radiopharmaceutical requires no further cold or refrigerated
storage, including with respect to shipping, subsequent to
stabilization. The preferred composition can be reconstituted "on
site" by the addition of a suitable diluent to bring the
radiopharmaceutical complex into solution at a desired
concentration.
Inventors: |
Kuperus; John H.; (Tampa,
FL) ; McKenzie; RobertG JR.; (Tampa, FL) ;
Schumm; Brooke III; (Ellicott City, MD) |
Correspondence
Address: |
BROOKE SCHUMM III
ONE NORTH CHARLES STREET
SUITE 2450
BALTIMORE
MD
21201
US
|
Family ID: |
35447603 |
Appl. No.: |
11/614882 |
Filed: |
December 21, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10904099 |
Oct 22, 2004 |
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11614882 |
Dec 21, 2006 |
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60580455 |
Jun 17, 2004 |
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60608060 |
Sep 8, 2004 |
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60522619 |
Oct 20, 2004 |
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Current U.S.
Class: |
424/1.11 ;
424/1.49 |
Current CPC
Class: |
A61K 51/10 20130101;
A61P 7/02 20180101; A61K 51/1241 20130101; A61K 51/1282 20130101;
A61P 35/00 20180101; A61P 25/00 20180101 |
Class at
Publication: |
424/001.11 ;
424/001.49 |
International
Class: |
A61K 51/00 20060101
A61K051/00 |
Claims
1. A method of preparing a stable rapidly lyophilized
radiopharmaceutical composition for diagnostic or therapeutic
purposes that needs no refrigeration upon completion of the method
and that increases the predictability of the integrity of the
radiopharmaceutical composition by reducing radiolysis damage,
comprising the following steps: evacuating a sealable chamber
containing a flash frozen amount of said radiopharmaceutical
composition having at least one radionuclide in at least one
lyophilization-stoppered but as yet unsealed vial, said evacuating
of said sealable chamber occurring by a vacuum pump connected by an
evacuation tube passing through a primary condenser and a secondary
condenser to lower pressure to below 10-2 Torr which is sufficient
to eliminate the explosive potential of liquid oxygen while
maintaining the temperature of said primary condenser above the
boiling point of oxygen at said pressure; activating said secondary
condenser to reduce said evacuation tube temperature below the
boiling point of oxygen in order to accelerate the removal of water
from said sealable chamber, thereby reducing more rapidly the
presence of water molecules, including radiolysis degenerated water
molecules, and reducing attendant free radical damage to said
radiopharmaceutical composition, and increasing the predictability
of the integrity of the radiopharmaceutical composition; and
restoring the ambient pressure in the sealable chamber to
approximately atmospheric pressure with a pharmaceutically inert
gas upon completion of the desired removal of water; and sealing
the said at least one vial in order to preclude entry of external
fluid.
2. The method according to claim 1, further comprising: said
evacuating said sealable chamber occurring at a primary condenser
temperature of approximately -40 degrees C. until said pressure
sufficient to eliminate the explosive potential of liquid oxygen
has reached approximately 10-2 Torr.
3. The method according to claim 2, further comprising: said
radiopharmaceutical composition having at least one ligand.
4. The method according to claim 3, further comprising: said at
least one ligand being selected from the group of BZM, Beta-CIT,
EDTMP, HIDA or fatty acids.
5. The method according to claim 3, further comprising: said
radiopharmaceutical composition having the ligand MIBG.
6. The method according to claim 2, further comprising: said
radiopharmaceutical composition having at least one monoclonal
antibody in combination with at least one lyophilization aid for
providing structural stabilization in combination with said at
least one monoclonal antibody.
7. The method according to claim 2, further comprising: said
radiopharmaceutical composition having at least one peptide in
combination with at least one lyophilization aid for providing
structural stabilization in combination with said at least one
peptide.
8. The method according to claim 2, further comprising: said
radiopharmaceutical composition having at least one molecular
recognition unit in combination with at least one lyophilization
aid for providing structural stabilization in combination with said
at least one molecular recognition unit.
9. The method according to claim 2, further comprising: said at
least one radionuclide being selected from the group of F-18, C-11,
Y-90, I-123, I-124, I-125, I-131, Cu-64, Cu-67, Co-55, Zn-62,
Fe-52, Ga-64, Ga-67, Ga-68, Br-77, Sr-89, Zr-89, Tc-99m, In-111,
Sm-153, Ho-166, Lu-177, Re-186, and Tl-201.
10. The method according to claim 9, further comprising: said
radiopharmaceutical composition having at least one ligand.
11. The method according to claim 10, further comprising: said at
least one ligand being selected from the group of BZM, Beta-CIT,
EDTMP, HIDA or fatty acids.
12. The method according to claim 10, further comprising: said
radiopharmaceutical composition having the ligand MIBG.
13. The method according to claim 9, further comprising: said
radiopharmaceutical composition having at least one monoclonal
antibody in combination with at least one lyophilization aid for
providing structural stabilization in combination with said at
least one monoclonal antibody.
14. The method according to claim 9, further comprising: said
radiopharmaceutical composition having at least one peptide in
combination with at least one lyophilization aid for providing
structural stabilization in combination with said at least one
peptide.
15. The method according to claim 9, further comprising: said
radiopharmaceutical composition having at least one molecular
recognition unit in combination with at least one lyophilization
aid for providing structural stabilization in combination with said
at least one molecular recognition unit.
16. The method according to claim 1, further comprising: said
radiopharmaceutical composition having at least one ligand.
17. The method according to claim 16, further comprising: said at
least one ligand being selected from the group of BZM, Beta-CIT,
EDTMP, HIDA or fatty acids.
18. The method according to claim 16, further comprising: said
radiopharmaceutical composition having the ligand MIBG.
19. The method according to claim 1, further comprising: said
radiopharmaceutical composition having at least one monoclonal
antibody in combination with at least one lyophilization aid for
providing structural stabilization in combination with said at
least one monoclonal antibody.
20. The method according to claim 1, further comprising: said
radiopharmaceutical composition having at least one peptide in
combination with at least one lyophilization aid for providing
structural stabilization in combination with said at least one
peptide.
21. The method according to claim 1, further comprising: said
radiopharmaceutical composition having at least one molecular
recognition unit in combination with at least one lyophilization
aid for providing structural stabilization in combination with said
at least one molecular recognition unit.
22. The method according to claim 1, further comprising: said at
least one radionuclide being selected from the group of F-18, C-11,
Y-90, I-123, I-124, I-125, I-131, Cu-64, Cu-67, Fe-52, Co-55,
Zn-62, Ga-64, Ga-67, Ga-68, Br-77, Sr-89, Zr-89, Tc-99m, In-111,
Sm-153, Ho-166, Lu-177, Re-186, and Tl-201.
23. The method according to claim 22, further comprising: said
radiopharmaceutical composition having at least one ligand.
24. The method according to claim 23, further comprising: said at
least one ligand being selected from the group of BZM, Beta-CIT,
EDTMP, HIDA or fatty acids.
25. The method according to claim 23, further comprising: said
radiopharmaceutical composition having the ligand MIBG.
26. The method according to claim 22, further comprising: said
radiopharmaceutical composition having at least one monoclonal
antibody in combination with at least one lyophilization aid for
providing structural stabilization in combination with said at
least one monoclonal antibody.
27. The method according to claim 22, further comprising: said
radiopharmaceutical composition having at least one peptide in
combination with at least one lyophilization aid for providing
structural stabilization in combination with said at least one
peptide.
28. The method according to claim 22, further comprising: said
radiopharmaceutical composition having at least one molecular
recognition unit in combination with at least one lyophilization
aid for providing structural stabilization in combination with said
at least one molecular recognition unit.
29. A method of preparing a stable rapidly lyophilized
radiopharmaceutical composition for diagnostic or therapeutic
purposes that needs no refrigeration upon completion of the method
and that increases the predictability of the integrity of the
radiopharmaceutical composition by reducing radiolysis damage,
comprising the following steps: evacuating a sealable chamber
containing a flash frozen amount of said radiopharmaceutical
composition having at least one radionuclide in at least one
lyophilization-stoppered but as yet unsealed vial, said said
evacuating of said sealable chamber occurring by a vacuum pump
through an evacuation tube passing through a secondary condenser to
a primary condenser to lower pressure to below 10-2 Torr which is
sufficient to eliminate the explosive potential of liquid oxygen
while maintaining the temperature of said primary condenser for
cooling above the boiling point of oxygen at said pressure;
activating said secondary condenser to reduce said evacuation tube
temperature below the boiling point of oxygen in order to
accelerate the removal of water from said sealable chamber, thereby
reducing more rapidly the presence of water molecules, including
radiolysis degenerated water molecules, and reducing attendant free
radical damage to said radiopharmaceutical composition, and
increasing the predictability of the integrity of the
radiopharmaceutical composition; and restoring the ambient pressure
in the sealable chamber to approximately atmospheric pressure with
a pharmaceutically inert gas upon completion of the desired removal
of water; and sealing said at least one vial in order to preclude
entry of external fluid.
30. The method according to claim 29, further comprising: said
evacuating said sealable chamber occurring at a primary condenser
temperature of approximately -40 degrees C. until said pressure
sufficient to eliminate the explosive potential of liquid oxygen
has reached approximately 10-2 Torr.
31. The method according to claim 30, further comprising: said
radiopharmaceutical composition having at least one ligand.
32. The method according to claim 31, further comprising: said at
least one ligand being selected from the group of BZM, Beta-CIT,
EDTMP, HIDA or fatty acids.
33. The method according to claim 31, further comprising: said
radiopharmaceutical composition having the ligand MIBG.
34. The method according to claim 30, further comprising: said
radiopharmaceutical composition having at least one monoclonal
antibody in combination with at least one lyophilization aid for
providing structural stabilization in combination with said at
least one monoclonal antibody.
35. The method according to claim 30, further comprising: said
radiopharmaceutical composition having at least one peptide in
combination with at least one lyophilization aid for providing
structural stabilization in combination with said at least one
peptide.
36. The method according to claim 30, further comprising: said
radiopharmaceutical composition having at least one molecular
recognition unit in combination with at least one lyophilization
aid for providing structural stabilization in combination with said
at least one molecular recognition unit.
37. The method according to claim 30, further comprising: said at
least one radionuclide being selected from the group of F-18, C-11,
Y-90, I-123, I-124, I-125, I-131, Cu-64, Cu-67, Co-55, Zn-62,
Fe-52, Ga-64, Ga-67, Ga-68, Br-77, Sr-89, Zr-89, Tc-99m, In-111,
Sm-153, Ho-166, Lu-177, Re-186, and Tl-201.
38. The method according to claim 37, further comprising: said
radiopharmaceutical composition having at least one ligand.
39. The method according to claim 38, further comprising: said at
least one ligand being selected from the group of BZM, Beta-CIT,
EDTMP, HIDA or fatty acids.
40. The method according to claim 38, further comprising: said
radiopharmaceutical composition having the ligand MIBG.
41. The method according to claim 37, further comprising: said
radiopharmaceutical composition having at least one monoclonal
antibody in combination with at least one lyophilization aid for
providing structural stabilization in combination with said at
least one monoclonal antibody.
42. The method according to claim 37, further comprising: said
radiopharmaceutical composition having at least one peptide in
combination with at least one lyophilization aid for providing
structural stabilization in combination with said at least one
peptide.
43. The method according to claim 37, further comprising: said
radiopharmaceutical composition having at least one molecular
recognition unit in combination with at least one lyophilization
aid for providing structural stabilization in combination with said
at least one molecular recognition unit.
44. The method according to claim 29, further comprising: said
radiopharmaceutical composition having at least one ligand.
45. The method according to claim 44, further comprising: said at
least one ligand being selected from the group of BZM, Beta-CIT,
EDTMP, HIDA or fatty acids.
46. The method according to claim 44, further comprising: said
radiopharmaceutical composition having the ligand MIBG.
47. The method according to claim 29, further comprising: said
radiopharmaceutical composition having at least one monoclonal
antibody in combination with at least one lyophilization aid for
providing structural stabilization in combination with said at
least one monoclonal antibody.
48. The method according to claim 29, further comprising: said
radiopharmaceutical composition having at least one peptide in
combination with at least one lyophilization aid for providing
structural stabilization in combination with said at least one
peptide.
49. The method according to claim 29, further comprising: said
radiopharmaceutical composition having at least one molecular
recognition unit in combination with at least one lyophilization
aid for providing structural stabilization in combination with said
at least one molecular recognition unit.
50. The method according to claim 29, further comprising: said at
least one radionuclide being selected from the group of F-18, C-11,
Y-90, I-123, I-124, I-125, I-131, Cu-64, Cu-67, Fe-52, Co-55,
Zn-62, Ga-64, Ga-67, Ga-68, Br-77, Sr-89, Zr-89, Tc-99m, In-111,
Sm-153, Ho-166, Lu-177, Re-186, and Tl-201.
51. The method according to claim 50, further comprising: said
radiopharmaceutical composition having at least one ligand.
52. The method according to claim 51, further comprising: said at
least one ligand being selected from the group of BZM, Beta-CIT,
EDTMP, HIDA or fatty acids.
53. The method according to claim 51, further comprising: said
radiopharmaceutical composition having the ligand MIBG.
54. The method according to claim 50, further comprising: said
radiopharmaceutical composition having at least one monoclonal
antibody in combination with at least one lyophilization aid for
providing structural stabilization in combination with said at
least one monoclonal antibody.
55. The method according to claim 50, further comprising: said
radiopharmaceutical composition having at least one peptide in
combination with at least one lyophilization aid for providing
structural stabilization in combination with said at least one
peptide.
56. The method according to claim 50, further comprising: said
radiopharmaceutical composition having at least one molecular
recognition unit in combination with at least one lyophilization
aid for providing structural stabilization in combination with said
at least one molecular recognition unit.
57. The method according to claims 1 through 56, further
comprising: said radiopharmaceutical composition being an imaging
agent selected from the group of imaging agents having a selective
affinity for the hepatobiliary system.
58. The method according to claims 1 through 56, further
comprising: said radiopharmaceutical composition being an imaging
agent selected from the group of imaging agents having a selective
affinity for the cardiac system.
59. The method according to claims 1 through 56, further
comprising: said radiopharmaceutical composition being an imaging
agent selected from the group of imaging agents having a selective
affinity for the cerebral system.
60. The method according to claims 1 through 56, further
comprising: said radiopharmaceutical composition being an imaging
agent selected from the group of imaging agents having a selective
affinity for the skeletal system.
61. The method according to claims 1 through 56, further
comprising: said radiopharmaceutical composition being an imaging
agent selected from the group of imaging agents used for prostate
imaging.
62. The method according to claims 1 through 56, further
comprising: said radiopharmaceutical composition being an imaging
agent selected from the group of imaging agents used for pulmonary
imaging.
63. The method according to claims 1 through 56, further
comprising: said radiopharmaceutical composition having at least
one chemical stabilizer.
64. The method according to claims 1 through 56, further
comprising: said radiopharmaceutical composition having at least
one bacteriastatic agent.
65. The method according to claims 1 through 56, further
comprising: said radiopharmaceutical composition having at least
one antimicrobial preservative.
66. The method according to claims 1 through 56, further
comprising: said radiopharmaceutical composition having at least
one solubilizing agent.
67. The method according to claims 1-5, 9-12, 16-18, 22-25, 29-33,
37-40, 44-46, and 50-53, further comprising: said
radiopharmaceutical composition comprising at least one
lyophilization aid.
68. The method according to claims 1-5, 9-12, 16-18, 22-25, 29-33,
37-40, 44-46, and 50-53, further comprising: said
radiopharmaceutical composition comprising at least one
lyophilization aid selected from the group of lactose, dextrose,
albumin, gelatin or sodium chloride.
69. The method according to claims 6, 13, 19, 26, 34, 41, 47, and
54, further comprising: said radiopharmaceutical composition having
at least one monoclonal antibody in combination with at least one
lyophilization aid selected from the group of lactose, dextrose,
albumin, gelatin or sodium chloride for providing structural
stabilization in combination with said at least one monoclonal
antibody.
70. The method according to claims 7, 14, 20, 27, 35, 42, 48, and
55, further comprising: said radiopharmaceutical composition having
at least one peptide in combination with at least one
lyophilization aid selected from the group of lactose, dextrose,
albumin, gelatin or sodium chloride for providing structural
stabilization in combination with said at least one peptide.
71. The method according to claims 8, 15, 21, 28, 36, 43, 49, and
56, further comprising: said radiopharmaceutical composition having
at least one molecular recognition unit in combination with at
least one lyophilization aid selected from the group of lactose,
dextrose, albumin, gelatin or sodium chloride for providing
structural stabilization in combination with said at least one
molecular recognition unit.
Description
[0001] This is a continuation-in-part of a pending U.S. utility
application Ser. No. 10/904,099 entitled Stabilized and Lyophilized
Radiopharmaceutical Agents which is a continuation-in-part of
provisional application No. 60/580,455 entitled Stabilized and
Lyophilized Radiopharmaceutical Agents filed on Jun. 17, 2004 and a
provisional application No. 60/608,060 of that name filed on Sep.
8, 2004, and a provisional application No. 60/522,619 filed on Oct.
20, 2004, and a continuation-in-part of U.S. application Ser. No.
11/611,862 filed Dec. 16, 2006 and Ser. No. 11/570,852 filed Dec.
18, 2006 which are US national stage entries of PCT/US2005/21847
which claim priority from the above 2004 applications and other
applications as more fully set forth in PCT/US2005/21847.
FIELD OF THE INVENTION
[0002] The present invention relates to the method of preparation
and stabilization of a diagnostic or therapeutic
radiopharmaceutical useful, for example, in mammalian imaging and
cancer detection, and resulting composition. In particular, the
present invention relates to the novel method of preparation of
radioactive diagnostic radiopharmaceutical in a stable, shippable,
lyophilized form by an apparatus designed to rapidly flash freeze
and dehydrate a radiopharmaceutical composition to minimize auto
radiolysis, the novelty centering on rapid cooling and removal of
ambient vapor, and then ultra cold removal when the potential of
explosive liquid oxygen is eliminated. The radioactive diagnostic
radiopharmaceutical requires no further cold or refrigerated
storage, including with respect to shipping, subsequent to
stabilization. The preferred composition can be reconstituted "on
site" by the addition of a suitable diluent to bring the
radiopharmaceutical complex into solution at a desired
concentration at the time of administration to the patient in need
of a therapeutic or diagnostic radiopharmaceutical. Heading
SUMMARY OF THE INVENTION
[0003] The present invention is directed to a stable radioactive
diagnostic radiopharmaceutical composition that may be formed
without stabilization additives and to a method of preparing such a
composition. Stabilization additives may be added. Traditional
techniques for freeze-drying (lyophilization) are subject to the
lengthy crystal formation time of water. The composition is formed
by avoiding that lengthy crystal formation time and the concurrent
loss of diagnostic specificity due to autoradiolysis of the
radiopharmaceutical. The length of traditional freeze-drying
techniques and loss of diagnostic specificity due to autoradiolysis
interfere with the technical accuracy necessary for nuclear
medicine.
[0004] The novel technique of the inventors involves utilization of
flash freeze techniques along with increasing the cold-exposed
surface area and then rapidly decreasing the vapor pressure as well
as super cold freeze drying of the radiopharmaceutical composition,
the combination of which results in extremely rapid
freeze-drying/lyophilization, enabling use of higher concentrations
of radionuclides in the small scale amounts used in
radiopharmaceutical imaging without damaging the ligands. The
radiopharmaceutical composition can be reconstituted immediately
prior to administration with confidence of little or no ligand
damage, or little or no damage to the non-radioactive bonds and
chemical structure of the composition.
[0005] The preferred composition results from forming a complex
between a gamma emitting radionuclide and a ligand in a suitable
solvent, generally an aqueous solution and then lyophilizing the
solution by use of small quantities in large surface area vessels
at vacuum pressure in conjunction with rapid sub-zero cooling. The
radioactive diagnostic radiopharmaceutical in this invention
requires no further cold or refrigerated storage, including with
respect to shipping, subsequent to stabilization. The lyophilized
radiopharmaceutical composition is shipped and stored and is often
reconstituted "on site" by the addition of a suitable diluent to
bring the radiopharmaceutical complex into solution at the time of
administration to the patient in need of a therapeutic or
diagnostic radiopharmaceutical. The present invention further is
directed to stable radioactive diagnostic radiopharmaceutical
compositions prepared by this method.
BACKGROUND OF THE INVENTION
[0006] With the invention of the Gamma Camera, and, just as
importantly, with the invention of better high-speed imaging
machines, pharmaceutical substances with radioactive "tags" have
become extremely important in medical imaging and treatment. The
concept is that a compound, or just as often, a part of a compound,
called a ligand, sometimes referred to as an "agent" or which bonds
to some other substance, is designed to target a particular area of
a mammal's body or a particular type of tissue or molecule in that
body. The compound, ligand or agent will be referred to as a ligand
for convenience sake. The mammal this is most often used on is the
human body, and references in this invention to a human are equally
applicable to any mammal, or for that matter to any animal or
plant.
[0007] For instance, certain ligands tend to concentrate in heart
muscle tissue. The concept behind radiopharmaceutical imaging is to
"tag" that ligand with a radioactive substance, i.e. radioactively
mark a substance to create an "imaging agent," so that a health
care provider can find out where the ligand exists or is
concentrating. By administering the radioactively tagged ligand,
and placing the patient in an imaging machine, a health care
provider can "look inside" a patient's body to assist in therapy or
diagnosis. If a person has poor heart circulation, the radionuclide
tagged ligand, such as Tc 99m TIBI, will not be well-circulated to
areas of the heart muscle which have compromised blood flow,
enabling evaluation of a person's "heart condition." Importantly,
the health care provider can often "look inside" without having to
actually cut open or invade the body (non-invasive technique), or
can minimize bodily invasion. Obviously, the continued presence of
radioactive substances is not desirable, so substances are selected
with a short "half-life." The half-life is a time defined as the
time in which the radioactive emission declines by one-half. The
diminution of radioactivity is referred to as radioactive decay.
Between the body washing out the radiopharmaceutical substances
used in conjunction with this invention, and the use of substances
with a short half-life, the amount of a patient's radioactive
exposure is minimized.
[0008] Radioactive pharmaceuticals are in common use in imaging
studies to aid in the diagnosis of a wide variety of illnesses
including cardiac, renal and neoplastic diseases. These
pharmaceuticals, known in the art as "imaging agents," typically
are based on a gamma-emitting radionuclide attached to a carrier
molecule or "ligand." Gamma-emitting radionuclides are the
radionuclides of choice for conducting diagnostic imaging studies
because, while gamma emitting radiation is detectable with
appropriate imaging equipment, it is substantially less-ionizing
than beta or alpha radiation. Thus, gamma emitting radiation causes
minimal damage to targeted or surrounding tissues.
[0009] Radioactive pharmaceuticals now are finding increased use as
diagnostic agents for finding neoplastic disorders, especially
tumors. Diagnostic radiopharmaceuticals generally incorporate a
gamma emitting radionuclide, the radiation emission being useful in
the detection of certain neoplastic disorders.
[0010] The radioactive marking or tagging is often done by
complexing the radioactive substance inside a group of ligands,
that is surrounding it by a complex of ligands, so that the desired
chemical characteristics are expressed toward the exterior of the
complex with the tag shielded by the outer complex and simply
carried along as a marker. The entire complex with the radioactive
element, also called a radionuclide, functions as a radioactive
marker, and can be more generally referred to as a
radiopharmaceutical.
[0011] The use of small quantities of drugs used for such
activities is desirable for cost reasons, and it is desirable to
minimize the amount of radioactive substance used.
[0012] While the efficacy of radioactive diagnostic and therapeutic
agents is established, it is also well known that the emitted
radiation can cause substantial chemical damage or destabilization
to various components in radiopharmaceutical preparations, referred
to as autoradiolysis. Emitted radiation causes the generation of
free radicals in water solutions, which free radicals are generally
peroxides and superoxides. Such free radicals can precipitate
proteins present in the preparations, and can cause chemical damage
to other substances present in the preparations. Free radicals are
molecules with unbonded electrons that often result because the
emissions from the radioactive element can damage molecules by
knocking apart water molecules forming hydroxyl radicals and
hydrogen radicals, leaving an element or compound with a shell of
charged electrons which seek to bond with other molecules and atoms
and destabilize or change those molecules and atoms. The
degradation and destabilization of proteins and other components
caused by the radiation is especially problematic in aqueous
preparations. Under the present art, the radiolysis causes the
aqueous stored ligand and radioactive isotope bonded to the ligand
to degenerate and destroys the complex which renders it useless for
imaging because the biological characteristics that localize the
complex to a tissue are gone. The degradation or destabilization
lowers or destroys the effectiveness of radiopharmaceutical
preparations, and has posed a serious problem in the art. Wahl, et
al, Journal of Nuclear Medicine, Vol 31, Issue 1 84-89, discuss the
fact that freezing radiolabeled antibodies at -70 degrees C.
stabilizes the molecule for an indefinite period but 80 to 90% of
the immunoreactivity is lost in as little as 24 hours when stored
at 4 degrees C.
[0013] If the ligands are permitted to reside with the radioactive
elements for an extended period, particularly in an aqueous
(water-based) solution, the radiolysis is increased. Thus, any
process to reduce the compounds to dried form has to be rapid and
yield predictable result. Further, to avoid the higher
concentrations and protect the ligands, presently the
radiopharmaceutical solution is diluted, but that in itself only
slows the drying time and complicates the problem and increases the
unpredictability of the non-radioisotope portion of the
radiopharmaceutical because of radiolysis. Heating the
radiopharmaceutical in solution to accelerate the drying and
removal of water has the undesirable effect of potentially damaging
the ligand since chemical activity normally increases upon heating
or injection of energy and therefore the effects of radiolysis are
also increased during this prolonged drying period with heating.
Most proteins are badly damaged upon heating. Certain ligands, such
as isonitrile, simply evaporate and disappear upon heating.
Further, minimization of localized heating at an atomic scale is
important to preserve both the small quantities needed and to yield
a specific concentration of desired product.
[0014] Wolfangel, U.S. Pat. No. 5,219,556, Jun. 15, 1993, entitled
stabilized therapeutic radiopharmaceutical complexes, expressed his
concern as follows: "The isotopes which are most useable with this
process are determined by practical considerations. Again, Tc-99m
would be a poor candidate for use since its six-hour half-life
makes lyophilization impractical, as the lyophilization step itself
generally takes about 24 hours to perform."
[0015] Facially, the '556 invention seemed to identify a useful
process and resulting composition, but the lyophilization step in
'556 invention, as the application stated, took about 24 hours. The
'556 invention stated: "The lyophilization is carried out by
pre-freezing the product, and then subjecting the frozen product to
a high vacuum to effect essentially complete removal of water
through the process of sublimation. The resultant pellet contains
the complex in an anhydrous form which generally can be stored
indefinitely, with practical consideration being given to the
half-life of the radionuclide. The intended period of storage for
radiopharmaceutical products is thus practically limited by the
half-life of the radionuclides. In the case of Re-186, for example,
the desired period of storage would range from 7 to about 30 days.
Thus, this pellet can be shipped to the end users of the product
and reconstituted with a diluent at the time of administration to
the patient with very little effort on the part of the health care
professional and/or nuclear pharmacist."
[0016] Because the procedures in '556 did not rapidly lyophilize
the product, and contemplated a 24 hour period for lyophilization,
the claims of '556 invention were necessarily limited to
utilization of a "therapeutic amount of an alpha- or beta-emitting
radionuclide." Wolfangel had observed that compounds with a
half-life of at least 12 hours are preferred. By contrast, the use
of Tc-99m, which also emits gamma rays, with a half-life of only
six hours, or the use of other similarly short-lived radioisotopes,
becomes impractical.
In a recent comprehensive text on the subject of lyophilization, a
pre-eminent authority in the field made the following
observations:
"Lyophilization is a multistage operation in which quite obviously
each step is critical. The main actors of this scenario are all
well known and should be under strict control to achieve a
successful operation.
[0017] The product, . . .
[0018] The surrounding "medium" . . .
[0019] The equipment, . . .
[0020] The process, which has to be adapted to individual cases
according to the specific requirements and low-temperature behavior
of the different products under treatment.
[0021] The final conditioning and storage parameters of the
finished product, which will vary not only from one substance to
another one but in relationship with its "expected therapeutic
life" and marketing conditions (i.e., vaccines for remote tropical
countries, international biological standards, etc.). In other
words a freeze-dryer is not a conventional balance; it does not
perform in the same way with different products. There is no
universal recipe for a successful freeze-drying operation and the
repetitive claim that "this material cannot be freeze-dried" has no
meaning until each successive step of the process has been duly
challenged with the product in a systematic and professional way
and not by the all-too-common "trial-and-error" game.
The freeze-drying cycle. It is now well established that a
freeze-drying operation includes:
[0022] The ad hoc preparation of the material (solid, liquid, paste
emulsion) to be processed taking great care not to impede its
fundamental properties. [0023] The freezing step during which the
material is hardened by low temperatures. During this very critical
period, all fluids present become solid bodies, either crystalline,
amorphous, or glass. Most often water gives rise to a complex ice
network but it might also be imbedded in glassy structures or
remain more or less firmly bound within the interstitial
structures. Solutes do concentrate and might finally crystallize
out. At the same time, the volumetric expansion of the system might
induce powerful mechanical stresses that combine with the osmotic
shock given by the increasing concentration of interstitial fluids.
[0024] The sublimation phase or primary drying will follow when the
frozen material, placed under vacuum, is progressively heated to
deliver enough energy for the ice to sublimate. During this very
critical period a correct balance has to be adjusted between heat
input (heat transfer) and water sublimation (mass transfer) so that
drying can proceed without inducing adverse reactions in the frozen
material such as back melting, puffing, or collapse. A continuous
and precise adjustment of the operating pressure is then compulsory
in order to link the heat input to the "evaporative possibilities"
of the frozen material. [0025] The desorption phase or secondary
drying starts when ice is being distilled away and a higher vacuum
allows the progressive extraction of bound water at above zero
temperatures. This again is not an easy task since overdrying might
be as bad as underdrying. For each product, an appropriate residual
moisture has to be reached under given temperatures and pressures.
[0026] Final conditioning and storage begins with the extraction of
the product from the equipment. During this operation great care
has to be taken not to lose the refined qualities that have been
achieved during the preceding steps. Thus, for vials, stoppering
under vacuum or neutral gas within the chamber is of current
practice. For products in bulk or in ampoules, extraction might be
done in a tight gas chamber by remote operation. Water, oxygen,
light, and contaminants are all important threats and must be
monitored and controlled. [0027] Ultimate storage has to be carried
according to the specific "sensitivities" of the products (at room
temperature, +4 C -20 C). Again uncontrolled exposures to water
vapor, oxygen (air), light, excess heat, or nonsterile environment
are major factors to be considered. This obviously includes the
composition and qualify of the container itself, i.e., glass
elastomers of the stoppers, plastic or organic membranes. [0028] At
the end, we find the reconstitution phase. This can be done in many
different ways with water, balanced salt solutions, or solvents
either to restore the concentration of the initial product or to
reach a more concentrated or diluted product. For surgical grafts
or wound dressing, special procedures might be requested. It is
also possible to use the product as such, in its dry state, in a
subsequent solvent extraction process when very dilute biochemicals
have to be isolated from a large hydrated mass, as is the case for
marine invertebrates. [emphasis added as underlined material;
italics in original]"
[0029] Rey, Louis and May, Joan C., editors,
Freeze-Drying/Lyophilization of Pharmaceutical and Biological
Products, pp. (Marcel Dekker, Inc., New York, Basel 1999 (Nat'l
Library of Medicine Call no. WI DR893B v. 96 1999)).
[0030] Professor Rey states in his introduction that he and two
others led the first conference in 1958 on cryobiology, including
freeze-drying of pharmaceuticals. Id. at 2.
[0031] Juxtaposing the most important underlined material from the
above excerpt from Professor Rey's commentary based on his
life-long experience, the following important principles are stated
to be the art as of 1999: [0032] a) "Lyophilization is a multistage
operation in which, quite obviously, each step is critical. The
main actors of this scenario are all well known and should be under
strict control to achieve a successful operation." [0033] b) In
other words, a freeze-dryer is not a conventional balance; it does
not perform in the same way with different products. There is no
universal recipe for a successful freeze-drying operation and the
repetitive claim that "this material cannot be freeze-dried" has no
meaning until each successive step of the process has been duly
challenged with the product in a systematic and professional way
and not by the all-too-common "trial-and-error" game. [0034] c) The
freeze-drying cycle. It is now well established that a
freeze-drying operation includes: . . . [0035] 1). preparation of
the material [0036] 2) The freezing step [0037] 3) The sublimation
phase or primary drying will follow when the frozen material,
placed under vacuum, is progressively heated to deliver enough
energy for the ice to sublimate. During this very critical period a
correct balance has to be adjusted between heat input (heat
transfer) and water sublimation (mass transfer) so that drying can
proceed without inducing adverse reactions in the frozen material
such as back melting, puffing, or collapse. A continuous and
precise adjustment of the operating pressure is then compulsory in
order to link the heat input to the "evaporative possibilities" of
the frozen material. [0038] 4) The desorption phase or secondary
drying starts when ice is being distilled away and a higher vacuum
allows the progressive extraction of bound water at above zero
temperatures. This again is not an easy task since overdrying might
be as bad as underdrying. For each product, an appropriate residual
moisture has to be reached under given temperatures and pressures.
[0039] 5) Final conditioning and storage . . . [0040] 6) Ultimate
storage . . . . . . reconstitution phase . . . [emphasis added as
underlined material; italics in original]"
[0041] The current patent art corroborates Professor Rey's
assertion of the need for progressive heating, particularly the
Wolfangel '556 art, and Corbo et al art, U.S. Pat. No. 6,024,938,
Feb. 15, 2000. Wolfangel '556 contains the heating step that
Professor Rey asserts is well-settled, while the present invention
omits that step while achieving a superior art, and sets out a
procedure that is not isolated to a particular product, but as
useful for all radiopharmaceuticals. Further, the present invention
presents an advantage of rapidity of process not seen in the prior
art.
[0042] Notably, Wolfangel not only specifically also includes a
heating step, but simultaneously and specifically states his
invention is not applicable to short-half-life radionuclides. Corbo
'938 also contains the heating step, as does DeRosch, U.S. Pat. No.
6,428,768, Aug. 6, 2002, and all except Wolfangel take upwards of
24 hours. Thus, the later developing art is in fact moving to
longer periods of time, notwithstanding the possible aspiration to
a shorter time.
[0043] This invention thus defies the conventional wisdom by
omitting the heating step, but lyophilizing, and dehydrating, and
thereby stabilizing a radiopharmaceutical capable of storage at
room temperature by a different technique, thereby achieving a
superior result as demonstrated by the comparative experimental
results discussed momentarily.
[0044] Wolfangel '556 proposed in his example 1 to first lyophilize
certain compounds, add the radionuclide complex, sparge with gas,
seal the vial and then heat it. Unfortunately, the heating to 100
degree C. renders the procedure useless in conjunction with most
proteins or peptides, and many commonly used complexes. Further,
the proposal was to use 1 ml of sodium perrhenate Re-186 containing
1 mg of rhenium, with water added to produce 3 ml. The quantities
contemplated were substantial and exposed the workers to
substantial amounts of radiation. In example 3, it was proposed
that the complex be frozen to -30 degree C. or colder and then
apply a vacuum, but it was proposed to apply shelf heat at 6 degree
per hour until a product temperature of 30 degree C. was reached,
at which time the temperature would be held for two hours. That
would require 12 hours. The procedure suffered from the infirmity
of not quickly removing water and therefore not preventing
radiolysis of the water and not preventing the generation of free
radicals which damage the complexes. The second example 2 followed
the first, but used smaller quantities, and proposed heating.
Example 3 proposed heating to 85 degree C. for 30 minutes which
would destroy most proteins and thereafter freezing and
lyophilizing the sealed vials.
[0045] For diagnostic imaging purposes, radiopharmaceuticals based
on a coordination complex comprised of a gamma-emitting
radionuclide and a chelate have been used to provide both negative
and positive images of body organs, skeletal images and the like.
The Tc-99m skeletal imaging agents are well-known examples of such
complexes. One drawback to the use of these radioactive complexes
is that while they are administered to the patient in the form of a
solution, neither the complexes per se nor the solutions prepared
from them are overly stable. Consequently, the coordination complex
and solution to be administered commonly are prepared "on site,"
that is, they are prepared by a nuclear pharmacist or health care
technician just prior to conducting the study. The preparation of
appropriate radiopharmaceutical compositions is complicated by the
fact that several steps may be involved, during each of which the
health care worker must be shielded from the radionuclide.
[0046] The preparation of stable radiopharmaceutical diagnostic
agents, due to the type of radioactivity, presents even greater
problems. These agents typically are based on a relatively
energetic gamma emitting radionuclide complexed with a chelate.
Frequently, the radionuclide/chelate complex is in turn bound to a
carrier molecule which bears a site-specific receptor. Thus, it is
known that a gamma emitting radionuclide attached to a
tumor-specific antibody or antibody fragment can destroy targeted
neoplastic or otherwise diseased cells via exposure to the emitted
ionizing radiation. Bi-functional chelates useful for attaching a
diagnostic radionuclide to a carrier molecule such as an antibody
are known in the art. See e.g. Meares et al., Anal. Biochem.
142:68-78 (1984).
[0047] For most imaging and diagnostic applications of
radiopharmaceutical complexes of the types mentioned above, the
nonradioactive portion(s) of the complex is prepared and stored
until time for administration to the patient, at which time the
radioactive portion of the complex is added to form the
radiopharmaceutical of interest. For example, attempts to prepare
radionuclide-antibody complexes have resulted in complexes which
must be administered to the patient just after preparation because,
as a result of radiolysis, immunoreactivity may decrease
considerably after addition of the radionuclide to the antibody. In
Mather et al., J. Nucl. Med., 28:1034-1036 (1987), a technique for
labeling monoclonal antibodies with large activities of radio
iodine using the reagent N-bromosuccinimide is described. The
authors suggest that the antibodies labeled in this manner be
administered to the patient immediately after preparation to avoid
losses of immunoreactivity. Other examples of the preparation of
the nonradioactive portion of the complex followed by on-site
addition of the radioactive portion are disclosed in U.S. Pat. No.
4,652,440 (1987). Further, in many situations, the radioactive
component of the complex must be generated and/or purified at the
time the radiopharmaceutical is prepared for administration to the
patient. U.S. Pat. No. 4,778,672 (1988) describes, for example, a
method for purifying pertechnetate and perrhenate for use in a
radiopharmaceutical.
[0048] According to Wolfangel '556, EP 250,966 (1988) describes a
method for obtaining a sterile, purified, complexed radioactive
perrhenate from a mixture which includes, in addition to the
ligand-complexed radioactive perrhenate, uncomplexed ligand,
uncomplexed perrhenate, rhenium dioxide and various other
compounds. Specifically, the application teaches a method for
purifying a complex of rhenium-186 and 1-hydroxyethylidene
diphosphonate (HEDP) chelate from a crude solution. Because of the
instability of the complex, purification of the rhenium-HEDP
complex by a low pressure or gravity flow chromatographic procedure
is required. The purification procedure involves the aseptic
collection of several fractions, followed by a determination of
which fractions should be combined. After combining the appropriate
fractions, the fractions are sterile-filtered and diluted prior to
injection into the patient. The purified rhenium-HEDP complex
should be injected into the patient within one hour of preparation
to avoid the possibility of degradation. The rhenium complex may
have to be purified twice before use, causing inconvenience and
greater possibilities for radiation exposure to the health-care
technician.
[0049] While the lyophilization process has been applied to various
types of pharmaceutical preparations in the past, the notion of
lyophilizing short lived gamma emitting radiopharmaceutical
preparations has not been addressed. In part, this is believed to
be due to skepticism of those skilled in the art that such a
procedure could be safely carried out. U.S. Pat. No. 4,489,053
(Azuma et al.; Dec. 18, 1984) relates to Tc-99m-based diagnostic
imaging agents. The patentee notes that the non-radioactive agents
may be prepared in lyophilized form and that stabilizers are
required to prevent radiolysis once the Tc-99m is added.
[0050] Thus, there is a need in the art for a method of centrally
preparing and purifying a stabilized diagnostic radiopharmaceutical
for shipment to the site of use in a form ready for simple
reconstitution prior to its administration in diagnostic
applications without the necessity of additional stabilizers.
Because of the length of the Wolfangel process, many of the protein
combinations with radionuclides are impractical because of the
sensitivity of the protein in combination to any free radical
attack caused by radioactive decay, and thus the present invention
is a novel means to enable practical commercial use of radionuclide
labelled proteins and peptides. The length also effectively
prohibits the use of shorter half life radionuclides because in
order to use them with the Wolfangel process, the concentrations of
the radionuclides have to be increased to account for the several
half lives during the 24 hours lyophilization and the time for
shipment, which concentration exposes workers to higher
concentrations of radioactivity and which time exposes the ligands
to radiolysis which decreases their predictability of use in the
patient, if they are effective at all. If, in order to avoid the
higher concentrations, more dilute amounts are used, then the
quantity of liquid involved jeopardizes the efficacy of
lyophilization. There is a particular need in the art for a method
of centrally preparing and purifying radionuclide-labeled
antibodies and antibody fragments, owing to their relatively
unstable immunoreactivities once in aqueous solution. Most
particularly, this invention enables the use of short-half-life
radionuclides with ligands potentially subject to radiolysis that
are stable with useful shelf life at room temperatures that can be
shipped in a commercially cheaper manner, and easily
reconstituted.
OBJECTIVES OF THE INVENTION
[0051] An object of the invention is to accelerate the removal of
water to minimize the peroxidation-related effects of radiolysis
because of the accelerated removal of water which facilitates
stabilization and predictability of concentration of a ligand or
non-radioactive portion of a radiopharmaceutical because of reduced
radiolysis.
[0052] An object of the invention is to use the minimization of
peroxidation-related effects to improve the preservation of the
chemical substituent complexes typically surrounding a
radionuclide.
[0053] An object of the invention is to use small quantities at
concentrations which enable accelerated lyophilization, longer
predictable storage and overnight shipment, and increase worker
safety. Corollary to this objective is the elimination of need for
cold storage and refrigeration.
[0054] An object of the invention is to use vials with an expanded
surface area, extremely cold temperatures and very low level
pressures in combination to accelerate lyophilization.
[0055] An object of the invention is to use a two stage system to
accelerate lyophilization by not only lowering vacuum pressure, but
also, after initial removal of oxidizing agents, to extract vapor
more rapidly by supercooling gas being evacuated.
[0056] An object of the invention is to create a stable vehicle for
delivering selectively toxic radionuclides to target tissues.
DETAILED DESCRIPTION OF THE INVENTION
[0057] In contrast to the Wolfangel '556 invention which stated:
"the lyophilization step itself generally takes about 24 hours to
perform," the present invention proposes to produce a stable
radiopharmaceutical complex by a lyophilization process which
"freeze-dries" the complex in five hours or less, normally 2-4
hours, and then requires no further refrigeration.
[0058] The preferred mode of the invention is utilized in
conjunction with Iodine-123 ("I-123" (123 being the sum of the
protons and neutrons)) radionuclides. The following illustrates the
compositions and processes of this invention, but is not meant to
limit the scope of the invention in any way.
[0059] An I-123 labelled compound such as
meta-iodo-benzyl-guanidine ("MIBG") is prepared. The concentration
is increased so that ultimately one-half milliliter or less will
equal one dose. For example the usual does of I-123 MIBG for a
typical patient would be 10 mCi (millicuries). Because the half
life is 12 hours, in order to allow for normal radioactive decay in
shipment so that the dose is 10 mCi upon administration, 36 mCi
would be mixed on the prior day anticipating overnight
shipment.
[0060] The condensing system is heavily insulated.
[0061] A hose runs from the top or side of the stainless steel pot
of the primary condenser to the vacuum pump.
[0062] A vacuum pump capable of producing a vacuum of at least 10-4
Torr would be used to evacuate the chamber. An appropriate vacuum
pump is model RV-12 available from BOCEdwards, an international
company, of Wilmington, Massachusets, which can be contacted
through the internet.
[0063] In order to achieve the composition contemplated in this
invention, the primary condensing coil is readied at or below -40
deg. C. Promptly after mixing the radiopharmaceutical composition,
the vial containing the radiopharmaceutical composition, in the
preferred mode the 0.36 ml. of aqueous I-123MIBG, is stoppered with
the lyophilization stopper, with the lyophilization stopper in a
position to permit passage of vapour. The vial and stopper will be
fully sealed at the end of the process.
[0064] The vial(s) is (are) placed into the tray and a sufficient
amount of liquid nitrogen is poured onto the tray in order to flash
freeze the vials by the heat transfer from the aqueous I-123MIBG
through the sides of the vial. Because of the small quantity which
is used and the high surface area of the vial, the freezing occurs
virtually instantaneously. The tray is placed into a stoppering
frame in the chamber with the inner tube connected and installed so
that at the end of the procedure, before the vacuum is broken, the
port to the inner tube can be opened and the tube will inflate and
force the stoppers fully into the vials in order to seal them.
[0065] As the liquid nitrogen evaporates off, a thermistor on one
of the vials is connected to the electrical connector on the rubber
stopper which connects to an outside temperature monitoring device.
The liquid nitrogen is allowed to evaporate, all the while
maintaining the temperature of the vial at or below -10 degrees
C.
[0066] The top of the chamber is installed and forms a seal with
the cylindrical side of the chamber. After evaporation of the
liquid nitrogen, the gas valve on top of the chamber is closed, and
the rubber stopper is installed.
[0067] After the tray containing the flash-frozen vials is placed
into the chamber, and the chamber has been sealed, the vacuum pump
is turned on. A vacuum pressure is first felt in the primary
condenser and any vapor in the chamber begins to flow out through
the secondary condenser and freezes in the primary condenser which
is kept at a temperature above the boiling point of oxygen, meaning
preferably kept at about -40 degrees C. A reasonably skilled
practitioner in the art would recognize that at 10-2 Torr and -40
degree C. the amount of oxygen present would be sufficiently low
that the danger of oxygen oxidation damage from liquid oxygen if
the temperature is lowered below -40 degree C. is eliminated. The
preferable level for activating the secondary condenser is 10-3
Torr. When the vacuum pump gauge shows the preferred level of 10-3
Torr, usually after about 20 minutes, liquid Nitrogen at -196
degrees C. is allowed to flow through the secondary condenser and
cool the stainless steel tube contained in the secondary condenser
through which gas evacuated from the chamber is flowing. The very
cold liquid Nitrogen in the secondary compressor is used to
increase the temperature difference between the secondary condenser
and the vial contents to accelerate the lyophilization. The
secondary condenser is placed in series with the primary condenser
and the evacuated chamber containing the tray of vials. The
secondary condenser takes over as the larger and faster heat sink
to capture the vaporized water. A reasonably skilled practitioner
would understand that the vacuum pump continues to run to the end
of the procedure, and the pressure continues to drop to the rated
capacity of the vacuum pump. A reasonably skilled practitioner
would know that the pump referenced, the model RV-12 available from
BOCEdwards, has a rated capacity of approximately 10-6. Thus, after
the system has been sealed and the pump is turned on, the pressure
drops through the 10-2 Torr and 10-3 Torr levels to the rated
capacity of the vacuum pump.
[0068] Because the acrylic chamber has no refrigeration, the
temperature of the vial and the vial contents tend to rise above 0
degrees C. after all of the water is removed. This signals the
completion of the cycle. The thermistor probe connected through the
rubber stopper to the outside monitoring device enables the
monitoring of the vial temperature. The vials would then be sealed
in partial pressure of pharmaceutically inert gas that is fully
dehydrated or "dry," meaning gas that is non-reactive with the
pharmaceutical composition, the gas preferably being argon or
nitrogen. An inner tube will have been placed in the chamber to be
inflated to force the stoppers into the vial to seal them. An
auxiliary cylinder of gas that is chemically inert relative to the
lyophilized radionuclide is used to gradually inflate the inner
tube through the valve to force the stoppers into the vials. The
vacuum is broken. The vial stoppers further secured with an
aluminum seal. At the end of the process upon warming, the water
which was frozen and subsequently melted will be drained from the
primary condenser.
[0069] The vials are ready to be shipped with predictable half
lives for the radionuclide and a stabilized ligand in powdered
form.
[0070] If it is desired to accelerate the lyophilization process,
inert gas may be admitted through the gas valve into the chamber to
displace any oxygen and enable the secondary condenser to be turned
on sooner. The displacement is necessary to prevent accumulation of
liquid oxygen in the secondary condenser. In the ordinary
procedure, if the secondary condenser is activated before the 10-3
level is reached, there is a risk of collecting liquid oxygen which
is potentially explosive.
[0071] The secondary condenser is in series with the primary
condenser, and could be located subsequent to the primary condenser
in the evacuation and condensing system.
[0072] The speed of the lyophilization process is positively
influenced by the lowering of the vapor pressure external to the
material being dried. Secondly, the speed is positively influenced
by the greater temperature difference between product being cooled
and the temperature of the condenser where the water is being
collected.
[0073] The radioactive diagnostic radiopharmaceutical in this
invention requires no further cold or refrigerated storage,
including with respect to shipping, subsequent to stabilization.
The lyophilized radiopharmaceutical composition is reconstituted
"on site" for administration to patients by the addition of a
suitable diluent to bring the radiopharmaceutical complex into
solution at the time of administration to the patient.
[0074] For administration, the I-123 labelled MIBG in the vial must
be reconstituted. Because of the minute quantity of material, the
vial of radionuclide complex, in the preferred mode the I-123
labelled MIBG will appear empty. The MIBG ligand is stable for
several days because of the absence of water which is the primary
substance from which free radicals are generated by gamma ray
collisions with water molecules. The gamma rays are being emitted
by the radionuclide, that is the I-123. The health care provider
would add up to 2 ml. of sterile normal saline. The desired dose
would be withdrawn and measured in a dose calibrator of a type
manufactured by Capintec of Montville, N.J. If the glass vial is
measured in the dose calibrator, the person measuring the dose must
recognize that the glass vial will decrease the apparent activity.
Upon calibration of the desired dose, the I-123 MIBG now
re-dissolved in the solution is promptly administered to the
patient.
[0075] The advantages are that the flash freezing and lowering of
vapor pressure result in quick formation and evaporation or
sublimation (evaporation from ice to water vapour (a gas)) of water
from the I-123 MIBG. The I-123 MIBG need not be shipped frozen in
dry ice nor need it be shipped for overnight delivery. Shipping in
dry ice over a weekend is generally not commercially practical. The
I-123 MIBG can be shipped over the weekend and be used on Monday
while simply maintaining it at room temperature or below.
[0076] In order to establish the advantages of the novel process
and resulting composition, a series of tests were run utilizing
meta iodo benzyl guanidine (MIBG) in which the radionuclide I-131
was the iodine in the MIBG.
[0077] The MIBG was prepared as follows: eight vials were prepared
of MIBG in solution with a radioactive concentration of MIBG of 1
mCi per vial. The MIBG in six of those vials were then stabilized
and lyophilized according to the process described in this
invention. One vial was frozen and maintained at a temperature of
-10 degrees, and another vial was simply refrigerated at
approximately 5 degrees.
[0078] Six vials were prepared according to the process in this
invention in order to enable several to be reconstituted from the
lyophilized state and their activity tallied.
[0079] The radioactive concentration of MIBG per vial was 1 mCi per
vial.
[0080] The results showing the percent of iodine remaining bound to
the MIBG are set forth in table I. One each of the vials was
reconstituted after 24, 48, 72 and 168 hours respectively.
TABLE-US-00001 0 24 hours hours 48 hours 72 hours 168 hours (1 wk.)
Lyophilized 96.3% 97% 96.6% 96.2% 95.9% and stabilized per
invention stored at room temp. Frozen -10.degree. 96.3% 94% 91% 84%
72% Refrigerated 96.3% 92% 85% 77% 55% .about.+5.degree.
[0081] In sum, the radiolysis damage was virtually eliminated from
the composition stabilized and lyophilized under this invention
while, as the prior art suggests, MIBG that was not so stabilized
and lyophilized per this invention deteriorated sharply in
activity.
[0082] As another example, I-131 Hippuran was prepared. The I-131
Hippuran was prepared as follows: 9 vials were prepared of I-131
Hippuran in solution with a radioactive concentration of MIBG of 1
mCi per vial. Each vial had 4 cc. The I-131 in seven of those vials
was then stabilized and lyophilized according to the process
described in this invention. One vial was frozen and maintained at
a temperature of -10 degrees, and another vial was maintained room
temperature. Room temperature was selected because Hippuran is
thought to be stable at room temperature even in conjunction with a
radioisotope.
[0083] The results showing the percent of Hippuran remaining bound
to the I-123 are set forth in table 2. One each of the vials was
reconstituted after 24, 48, 72 and 168 hours respectively.
TABLE-US-00002 TABLE 2 0 hours 24 hrs 48 hrs 72 hrs 96 hrs 120 hrs
Lyophilized 98% 98.4% 98.6% 98% 98.4% 98.5% and stabilized per
invention stored at room temp. Frozen -10.degree. 98% 97.8% 97% 94%
92.5% 91 Room Temp. 98% 96% 95% 94.5% 92% 90%
[0084] In sum, the radiolysis damage was virtually eliminated from
the composition stabilized and lyophilized under this
invention.
[0085] If one desires to ship product, maintaining a product
reliably frozen even at -10 degrees is difficult and expensive as a
practical matter; this invention makes such shipment practical over
the techniques of the prior art. One reference has suggested that
storage at -70.degree. C. can limit autoradiolysis damage, but even
in that article, the percent free iodine, e.g. unbonded iodine,
rose from what appears to be 1.6% to 4.3% in 24 hours. Wahl,
Inhibition of Autoradiolysis of Radiolabeled monoclonal Antibodies
by Cryopreservation, 31(1) J. Nucl. Med. 84-89 (January 1990).
Conversely, putting those results in a form analogous to Table I,
the percentage of free iodine in the Wahl article commenced at
98.4% and fell in 24 hours to 95.7% in Wahl's Table 1. The contrast
between that fall in bonded iodine in 24 hours of some 3.7% in the
Wahl reference versus a fall of 0.4% during a week for the
composition stabilized and lyophilized per this invention
illustrates the sharp advantage of the present method and resulting
composition. In addition, it is not practical in real-world
conditions to replenish the cooling fluid to maintain -70.degree.
C. much less to ship it cost-effectively.
[0086] The micro quantities involved for radionuclide complexes
such as I-123 MIBG substantially reduce the exposure of production
workers and health care providers because minute quantities are
involved.
[0087] More generally, the preferred mode will use compounds that
have a half life of one hour to a maximum of 12 hours. Longer half
lives are less used because of slower radioactive decay exposing
the body to increased radiation. It is generally preferable to
apply the flash-freezing first because application of the reduced
pressure may cause the solution to boil out of the vial.
[0088] Applying the invention more generally, the intent is to
utilize the invention to produce stabilized radiopharmaceutical
compositions. Such stabilized radiopharmaceutical compositions
include radionuclides which are combined with ligand useful for
diagnosis or diagnostic treatment or therapy to form
radiopharmaceutical complexes in solution or suspension. These
complexes then are lyophilized in accord with the above procedure
according to the desired radioactivity level for the selected
radionuclide. The form of radiopharmaceutical composition
lyophilized according to this invention can be stored until needed
for use. This invention allows for the central preparation,
purification and shipment of a stabilized form of a
radiopharmaceutical complex which merely is reconstituted prior to
use. Thus, complicated or tedious formulation procedures, as well
as unnecessary risk of exposure to radiation, at the site of use
are avoided.
[0089] The radioactive diagnostic radiopharmaceutical in this
invention requires no further cold or refrigerated storage,
including with respect to shipping, subsequent to
stabilization.
[0090] The term "radiopharmaceutical composition" includes any
chemical composition including a radionuclide. Such term
"radionuclide" includes cyclotron-produced radionuclides including
those referenced in Table 1 on page 7 of M. Welch and C. Redvanly,
Handbook of Radiopharmaceuticals: Radiochemistry and Applications
(John Wiley & Sons, Ltd, Chichester, West Sussex, England 2003)
(hereafter "Handbook of Radiopharmaceuticals"), Table III on p. 77
of the Handbook of Radiopharmaceuticals, and throughout chapters 1
and 2 of the Handbook of Radiopharmaceuticals. Such term
"radionuclide" includes reactor-produced radionuclides including
those referenced in Table 2 on page 98 of the Handbook of
Radiopharmaceuticals and throughout chapter 3 of the Handbook of
Radiopharmaceuticals. Radionuclide also includes radioactive
isotopes of any element referenced in the Table 1 and Table 2
referenced in this paragraph, and includes Cu64 (which has
traditionally not been recognized as useful), Fe, including Fe52
and 5959 and Fe3+ radioisotopes, Yt, and Bi. Details of Gallium,
Indium, and Copper radionuclides included are referenced in Tables
1 on page 264, Table 4 on page 374, and Table 1 on page 402 of the
Handbook of Radiopharmaceuticals, respectively. Other useful
radionuclides, which sometimes overlap those of Table 1 and Table 2
just referenced can be found for iodine radionuclides at p. 424 of
the Handbook of Radiopharmaceuticals, and bromine radionuclides at
p. 442 of the Handbook of Radiopharmaceuticals. The Technetium
radionuclides and technetium radiopharmaceutical compositions are
included. The term radiopharmaceutical composition is intended to
be comprehensive because of the utility of the invention to
radiopharmaceuticals and their longer-term preservation. Therefore,
the term is defined to include the ligands bonded with
radionuclides, compounds in which the radionuclide is integral to
the ligand or compound, and compounds or mixtures in which the
radionuclide is complexed. Accordingly, further amplification of
the comprehensive scope of radiopharmaceutical composition is given
herein.
[0091] The term "radiopharmaceutical composition" includes isotopes
that are beta particle emitters, including those listed in Table 2
on page 773 of the Handbook of Radiopharmaceuticals, and Fe52,
Cu64, Cu67, Ga68, Br77 and 1124.
[0092] The term "radiopharmaceutical composition" includes
radionuclides bonded to a ligand. For the purposes of this
application, the term "ligand" is taken to mean a bio-compatible
vehicle, typically a molecule, capable of binding a radionuclide
and rendering the radionuclide appropriate for administration to a
patient. Thus, by way of illustration and not limitation, the term
ligand encompasses both chelating agents capable of sequestering
the radionuclide (usually a chemically-reduced form of the
radionuclide) as well as carrier molecules, such as lipophilic
cations with radioisotope labeling, antibodies, antibody fragments,
fatty acids, amino acids or other peptides or proteins. The term
radiopharmaceutical composition includes receptor specific agents,
tumor agents, tumor associated antigen, antithrombotic GPIIb/IIa
receptor antagonists, agents for neuroreceptors/transporters and
amyhloid plaque, BZM, and monoclonal or polyclonal antibodies,
particularly in Tc radiopharmaceuticals where preservation of the
ligand is important (a general summary of which is on p. 349 of the
Handbook of Radiopharmaceuticals). The application of the invention
to compounds for assessment of multi-drug resistance status is
contemplated. Chelating agents can include bifunctional and
multifunctional chelates. A non-exhaustive list of chelating agents
is referenced on pages 366 and page 376 of the Handbook of
Radiopharmaceuticals. Included in the term ligand are antibodies
bound via a chelate. Such antibodies may include monoclonal
antibodies or polyclonal antibodies. Other ligands contemplated
include neuroreceptor imaging agents, and receptor imaging agents,
and myocardial sympathetic nerve imaging agents, many of which are
referenced in Handbook of Radiopharmaceuticals. The carrier
molecules often are specifically targeted at a tumor cell or
tumor-specific antigen, an organ or a system of interest for
observational and consequent diagnostic purposes, or in need of
therapy. Carrier molecules may be directly labeled with the
radionuclide, in which case any pharmaceutically acceptable
counter-ion for the therapy or diagnostic intended may be used. The
radionuclide may be bound to a carrier molecule via a chelate or
other binding functionality. The term "complex" is taken to mean,
broadly, the union of the radionuclide and the ligand to which it
is attached. The chemical and physical nature of this union varies
with the nature of the ligand. The invention includes compounds in
the Handbook of Radiopharmaceuticals seeking receptors, including
so-called antagonists which fit receptors, a partial, but fairly
complete list of which is found on pages 452-457 and 717 of the
Handbook of Radiopharmaceuticals.
[0093] The term "radiopharmaceutical composition" refers to a
composition including the radionuclide-ligand complex as well as
suitable stabilizers, preservatives and/or excipients appropriate
for use in the preparation of an administrable pharmaceutical. The
invention contemplates that for certain large proteins susceptible
to breaking from the freezing process, such large protein
structures would be supported by a lyophilization aid known to
reasonably skilled practitioners in the art of pharmacy such as
lactose, dextrose, albumin, gelatin or sodium chloride.
[0094] The term "radiopharmaceutical composition", includes, for
therapeutic purposes, therapeutic radionuclides, including Auger
electron emitters such as those described on pages 772 and 776 of
the Handbook of Radiopharmaceuticals. Auger electron emitters can
be useful because they can result in additional deposition of
energy in tissue as to which radiopharmaceutical damage is desired.
Such damage is generally desired to be minimized in diagnostic
uses.
[0095] The general method of this invention, and the composition
contemplated to be created can be implemented on a general basis as
follows: after a radiopharmaceutical composition is prepared by
known methods appropriate to the composition, aliquots of the
radioactive complex are aseptically dispensed into sterile vials
consistent with the procedure outlined and the radioactive product
is lyophilized according to the procedure of this invention to
produce the stable lyophilized powder. The virtually complete
absence of water results in a substantial improvement in the
stability of the preparation, from both radio chemical purity and
chemical purity standpoints, versus prior preparations. The
stabilized complex can be prepared several days in advance, shipped
and stored until needed for use. The preferred mode of the
invention is focused on radionuclides that are gamma emitters of
diagnostic value and with a half-life sufficiently long to make the
preparation, lyophilization and shipment of the compounds
practical, but the invention is useful for alpha- and beta-emitting
radionuclides.
[0096] As an example of an additional preferred mode of invention,
Cu64 can be complexed with zinc isonitrile and Cu64 isonitrile can
be used for PET (Positron Emission Tomography) imaging. Without the
use of the process and composition of Cu64 isonitrile described
herein, the half-life of Cu64 is such that its use as an imaging
agent is relatively impractical. For cardiac imaging, the use of an
I123 or I124 isotope in combination with a fatty acid is useful on
a broader patient base than the current commonly used FDG imaging.
In order to use 2-deoxy-2-[18F]fluoro-D-glucose [18FDG] for imaging
the heart, the heart must be converted from fatty acid metabolism
to glucose metabolism which is accomplished by feeding the patient
high levels of glucose, usually three or four candy bars and
waiting for approximately an hour. This is unhealthy for diabetics.
This invention enables the use of shorter half-life compounds and
in particular the I123 or I-124 fatty acid radiopharmaceuticals and
eliminates the necessity of conversion of the heart from fatty acid
metabolism to glucose metabolism. This process and the composition
of the invention present a novel opportunity to use radioisotopes
of shorter half-lives. I-124 radionuclides generally, and I-124
fatty acid radiopharmaceuticals can be used in conjunction with PET
imaging.
[0097] Another preferred mode of invention is to use I124 MIBG for
neuroendocrine imaging and I124 fatty acids both stabilized by the
lyophilization process in this invention. Once again, only with the
invention is the use of I124 practical to sufficiently concentrate
the I124 while preserving the integrity of the overall I124
radiopharmaceutical composition. The use of I123 radionuclides is
also made more practical by this invention, particularly in
conjunction with fatty acid labeling.
[0098] At the point of use, the radiopharmaceutical compositions of
the present invention are prepared for administration to a patient.
Such preparation advantageously merely involves reconstitution with
an appropriate diluent to bring the complex into solution. This
diluent may be sterile water for injection (SWFI), dextrose and
sodium chloride injection or sodium chloride (physiological saline)
injection, for example. The preferred diluent is water for
injection or physiological saline (9 mg/ml) which conforms to the
requirements listed in the U.S. Pharmacopeia.
[0099] The present invention is particularly well suited for the
preparation of stable, pre-labeled antibodies for use in the
diagnosis and treatment of cancer and other diseases. For example,
antibodies expressing affinity for specific tumors or
tumor-associated antigens are labeled with a diagnostic
radionuclide, either directly or via a bi-functional chelate, and
the labeled antibodies are stabilized through lyophilization. Where
a bi-functional chelate is used, it generally is covalently
attached to the antibody. The antibodies used can be polyclonal or
monoclonal, and the radionuclide-labeled antibodies can be prepared
according to methods known in the art. The method of preparation
will depend upon the type of radionuclide and antibody used. The
stable, lyophilized, radio labeled antibody merely is reconstituted
with suitable diluent at the time of intended use, thus greatly
simplifying the on site preparation process. The process of this
invention can be applied to stabilize many types of pre-labeled
antibodies, including, but not limited to, polyclonal and
monoclonal antibodies to tumors associated with melanoma, colon
cancer, breast cancer, prostate cancer, etc. Such antibodies are
known in the art and are readily available. Other ligands with
specific affinities to sites in need of radiotherapy are known in
the art and will continue to be discovered.
[0100] The radiopharmaceutical composition which results from the
method of this invention may be further purified after
reconstitution, if desired. One method of purification is described
in EP 250966, noted above. Other methods are known to those skilled
in the art.
[0101] The radiopharmaceutical composition can include other
components, if desired. Useful additional components include
chemical stabilizers, lyophilization aids and microbial
preservatives. Such chemical stabilizers include ascorbic acid,
gentisic acid, reductic acid, para-amino benzoic acid, and
erythorbic acid among others. In some cases, these agents are
beneficial in protecting the oxidation state of the radionuclide by
preferential reaction with oxygen or by direct effect. The term
lyophilization aids includes those substances known to facilitate
good lyophilization of the product. These aids are used to provide
bulk and stability to the dried pellet and include lactose,
dextrose, albumin, gelatin, sodium chloride, mannitol, dextran and
pharmaceutically-acceptable carriers, among others. Antimicrobial
preservatives inhibit the growth of or kill microbial contaminants
which are accidentally added to the product during preparation. The
term antimicrobial preservatives includes methylparaben,
propylparaben and sodium benzoate. These components generally are
added to the composition after the complex has been formed between
the ligand and the radionuclide but prior to lyophilization.
Bacteriastatic agents, for example, methyl and propyl-paraben may
be added. Also contemplated are the addition of solubilizing agents
such as polyethylene glycol to enhance the solubility of fatty acid
compounds tagged with radionuclides in normal saline solution or
other water based solutions.
[0102] The above process, apparatus and resulting composition is
adaptable to the stabilization and preservation of virtually all
radionuclides whatever the solvent used for initial composition.
Some preferred applications include stabilization of radiolabeled
peptides, [18 F] deoxyglucose, radiolabelled annexin, 99
mTc-annexin, radiolabelled monocyte chemoattractant protein. i.e.
125-I-(MCP-1), radiolabelled Dopamine transporter agents,
(S)-N-(1-ethylpyrrolidin-2-ylmethyl)-2-hydroxy-3-iodo-6-methoxybenzamide
(3-IBZM)(More generally "BZM,),
(S)-N-(1-ethylpyrrolidin-2-ylmethyl)-2-hydroxy-5-iodo-6-methoxybenzamide
(5-IBZM), 1-123-2-beta-carbomethoxy-3-beta(4-iodophenyl) N-(3-fluro
propyl) nortropane ("CIT" or "beta-CIT") and various tropane
derivatives, I-123 fatty acids, particularly for cardiovascular
imaging, radiolabelled octreotide or radiolabelled depreotide, HEDP
(diagnostic skeletal imaging or treatment of metastatic bone pain),
radiolabelled antibodies, both polyclonal and monoclonal, with
selective affinities for tumor-associated antigens diagnosis or in
situ radiotherapy of malignant tumors such as melanomas), and
ligands with selective affinity for the hepatobiliary system (the
liver-kidney system), including
2,6-dimethylacetanilideiminodiacetic acid and the family of other
imidoacetic acid group-containing analogs thereof (collectively
referred to herein as "HIDA agents"), mono-, di- and polyphosphoric
acids and their pharmaceutically-acceptable salts including
polyphosphates, pyrophosphates, phosphonates, diphosphonates and
imidophosphonates. Preferred ligands are 1-hydroxyethylidene
diphosphonate, methylene diphosphonate, (dimethylamino)methyl
diphosphonate, methanehydroxydiphosphonate, and imidodiphosphonate
(for bone-scanning and alleviation of pain); strontium 89 ethylene
diamine tetramethylene phosphate, samarium 153-ethylene diamine
tetramethylene phosphate, radiolabelled monoclonal antibodies,
99m-Tc HMPAO (hexamethylproplyene amine oxime), yttrium 90-labeled
ibritumomab tiuxetan (Zevalin.RTM. Registered Trademark of Biogen
Idec, Inc.), and meta-iodo-benzyl guanidine. Ethylene diamine
tetramethylene phosphate and ethylene diamine tetramethylene
phosphoric acid and the pharmaceutically related mono-, di- and
polyphosphoric acids and their pharmaceutically-acceptable salts
including polyphosphates, pyrophosphates, phosphonates,
diphosphonates and imidophosphonates are collectively called
EDTMP.
[0103] Suitable radionuclides which are well-known to those skilled
in the art include radioisotopes of copper, technetium-99m,
rhenium-186, rhenium-188, antimony-127, lutetium-177,
lanthanum-140, samarium-153, radioisotopes of iodine, indium-111,
gallium-67 and -68, chromium-51, strontium-89, radon-222,
radium-224, actinium-225, californium-246 and bismuth-210. Other
suitable radionuclides include F-18, C-11, Y-90, Co-55, Zn-62,
Fe-52, Br-77, Sr-89, Zr-89, Sm-153, Ho-166, and Tl-201.
[0104] The invention is not meant to be limited to the disclosures,
including best mode of invention herein, and contemplates all
equivalents to the invention and similar embodiments to the
invention for humans, mammals and plant science. Equivalents
include combinations with or without stabilizing agents and
adjuncts that assist in reservation, and their pharmacologically
active racemic mixtures, diastereomers and enantiomers and their
pharmacologically acceptable salts in combination with suitable
pharmaceutical carriers.
* * * * *