STABLE FORMULATIONS OF INDOCYANINE GREEN
FIELD OF THE INVENTION
The present invention is related to indocyanine green (ICG) formulations with
improved stability and process for preparing such stable formulations.
BACKGROUND OF THE INVENTION
Indocyanine green is a fluorescent cyanine dye used in determining hepatic
function, cardiac output, liver blood flow and ophthalmic angiography. The product
is marketed by Akorn as a lyophilized powder to be reconstituted with water for
injection (WFI) for parenteral administration. It is to be used within six hours of
reconstitution as it is unstable in aqueous solution. The U.S Food and Drug
Administration has approved IC-Green
TM
for determining cardiac output, hepatic
function, liver blood flow and for ophthalmic angiography.
U.S Patent No. 6,944,493 to Akorn et al., discloses indocyanine green compositions
exhibiting enhanced stability and enhanced indocyanine green concentration
compared to the indocyanine green products on the market. The patent discloses
indocyanine green liposomal formulations which are stable for at least 24 hours
after reconstitution. All the formulations disclosed in this patent are reconstituted
with a diluent solution comprising ethanol and polysorbate 80 among others.
U.S Patent application No. 2004/0156782 to Abu Alam et al., discloses methods of
using indocyanine green dye. The publication provides methods for the diagnosis
and treatment of lesions in an animal using an aqueous indocyanine green
composition that is administered to the patient more than 10 hours after
reconstitution.2
U.S Patent No. 9,289,517 to Goutayer Mathieu et al., discloses nano-emulsion
formulations of indocyanine green. The formulation of this invention are based on
phospholipids and require elaborate manufacturing technique.
The formulations of the prior art need expensive equipment, long manufacturing
process times and specialized excipients and in some cases, excipients like alcohol
and polysorbate that make the administration of injection painful and challenging.
On the contrary, the formulations of the present invention are stable, cost effective
and are easy to manufacture. These formulations further do not cause any
discomfort to the patient at the time of administration.
SUMMARY OF THE INVENTION
One aspect of the invention is directed to a stable, alcohol free parenteral
formulation of indocyanine green.
Another aspect of the present invention is to provide an alcohol free parenteral
formulation of indocyanine green that is stable up to 24 hours after reconstitution
with water for injection.
Yet another aspect of the present invention is to provide an alcohol free parenteral
formulation of indocyanine green that is stable up to 24 hours after reconstitution
with 0.9% Sodium chloride (Normal Saline).
Yet another aspect of the present invention is to provide an alcohol free parenteral
formulation of indocyanine green that is stable up to 24 hours after reconstitution
with 0.45% Sodium chloride (1/2 Normal Saline).
Yet another aspect of the present invention is to provide an alcohol free parenteral
formulation of indocyanine green that is stable up to 24 hours after reconstitution
with any other aqueous diluents, like dextrose solution.3
Yet another aspect of the present invention is to provide a kit comprising a stable
alcohol free formulation of indocyanine green, wherein vial comprises lyophilized
powder of indocyanine green optionally together with excipients and a vial
comprising a diluent solution.
DETAILED DESCRIPTION OF THE INVENTION
The term indocyanine green described in the present invention refers to
pharmaceutically acceptable salts, solvates, hydrates, acids, anhydrous and free
base forms thereof, preferably indocyanine green.
The term stable refers to formulations which remain stable during the entire shelf
life of the formulation. The term stable in the present invention relates to
formulations with improved stability as compared to RLD, after reconstitution with
water for injection or 0.9% Sodium chloride or 0.45% Sodium chloride or any other
aqueous diluent, like dextrose solution.
The term “stabilizer” or stabilizing agent in the present invention refers to an agent
that improves or imparts stability to the formulation throughout the shelf life.
The term “parenteral formulations” refers to stable formulations of indocyanine
green intended for parenteral administration.
The term “osmolality” refers to measure of the osmotic pressure exerted by a real
solution across a semipermeable membrane. A quantitative measure of osmotic
pressure facilitates the dilution required to render a solution iso-osmotic relative to
whole blood.
The term “free of alcohol” or “free of ethanol” refers to pharmaceutical
compositions containing 0 to < 5%w/v of alcohol or ethanol respectively.4
The present invention provide compositions with greater stability as compared to
the currently available market formulation (RLD). The inventive compositions of
the present invention comprise indocyanine green preferably in the form of a
lyophilized powder with disodium hydrogen phosphate, sodium dihydrogen
phosphate and sodium chloride. The lyophilized powder is further reconstituted
with water for injection or 0.9% Sodium chloride or 0.45% Sodium chloride or any
other aqueous diluents, like dextrose solution.
The disadvantage of the present approved IC-Green
TM
is that the stability is only
for 6 hours after reconstitution. Therefore, any unused solution has to be discarded
after 6 hours. One aspect of the present invention relates to a formulation of
indocyanine green that forms a solution that is stable up to 24 hours after
reconstitution.
Another aspect of the present invention relates to an ethanol free formulation of
indocyanine green. The prior art formulations reported for indocyanine green are
either formulations that are based on liposomes or are biphasic like emulsions or
contain ethanol in significant quantities. For instance, US 6944493 discloses
formulations of indocyanine green containing ethanol in a concentration of
100mg/mL which may cause irritation to the patient. The patent also teaches the use
of alcohol: ranging from 7.5%w/v to 12.5%w/v or 5.0%w/v -15%w/v, ethanol:
10%w/v, Benzyl alcohol: 1%w/v and polysorbate: 0.2%w/v in significant amounts
and specifies that they are essential for the stability of the formulation. On the other
hand, the formulations of the present invention are free of ethanol and polysorbate,
both of which are known to cause hemolysis at the time of administration.
An embodiment of the present invention relates to a stable formulation comprising
lyophilized powder of indocyanine green, disodium hydrogen phosphate, sodium
dihydrogen phosphate and sodium chloride and optionally other pharmaceutically
acceptable excipients.5
A preferred embodiment of the present invention comprises a formulation
comprising lyophilized powder of indocyanine green, disodium hydrogen
phosphate, sodium dihydrogen phosphate and sodium chloride and optionally other
pharmaceutically acceptable excipients, wherein the formulation is free of alcohol.
Another preferred embodiment of the present invention relates to a kit comprising
lyophilized powder of indocyanine green, disodium hydrogen phosphate, sodium
dihydrogen phosphate and sodium chloride and optionally other pharmaceutically
acceptable excipients packed together with a diluent vial comprising water for
injection or 0.9% Sodium chloride or 0.45% Sodium chloride or any other aqueous
diluent, like dextrose solution.
The pharmaceutical formulations of the present invention may contain one or more
excipients selected from the group comprising disodium hydrogen phosphate,
sodium dihydrogen phosphate, sodium chloride, citrate, sodium carbonate, sodium
bicarbonate, tartarate, benzoate, acetate, boric acid, lactic acid, glutaric acid, malic
acid, succinic acid and carbonic acid, alkali or alkaline earth salt of one of these
acids, Tris, meglumine, amino acid buffers such as arginine, alanine, histidine,
glycine, lysine and the like.
The formulation of the present invention may additionally contain pH adjusting
agents selected from the group comprising sodium hydroxide, potassium hydroxide,
ammonium carbonate, hydrochloric acid, citric acid, lactic acid, phosphoric acid
and sulfuric acid. Further, the present invention also may contain anti- microbial
agents.
Since the current marketed product of indocyanine green has poor aqueous stability,
this limits usage in different imaging applications. Therefore there is a need for
improving aqueous stability of ICG. The inventor's product showed about 10 fold 6
improvement in aqueous stability of solutions of ICG and this results in adequate
time being available for administering the drug to performing imaging.
The following Examples are intended to illustrate the present invention and are not
to be considered as limiting the scope of the invention.
Example 1:
S. No Ingredients
F1
mg/mL % w/v
1. Indocyanine Green 25 2
2. Disodium Hydrogen phosphate 3.06 0.2448
3. Sodium dihydrogen phosphate 3.06 0.2448
4. Sodium Chloride 10.03 0.8024
5. Water for Injection Q.S. 1.25 mL 100
Manufacturing process:
Indocyanine green was dissolved in water for injection by stirring. Dispensed
quantities of Disodium hydrogen phosphate, Sodium dihydrogen phosphate and
Sodium chloride were added to the above solution and stirred. Further volume was
adjusted to 100% with remaining quantity of water for injection. The bulk solution
was filled into vials and loaded over precooled shelves of lyophilizer and subjected
for freeze drying. After completion of lyophilization process, vials were withdrawn,
stoppered and sealed. The lyophilized vials are packed into a kit comprising the
lyophilized product and a diluent vial.
Example 2:
S. No Ingredients
F2 F3
mg/mL % w/v mg/mL % w/v
1. Indocyanine Green 25 1.25 25 1.25
2. Disodium Hydrogen phosphate 1.53 0.0765 2.43 0.1215
3. Sodium dihydrogen phosphate 1.53 0.0765 2.43 0.12157
4. Sodium Chloride 5.01 0.2505 7.98 0.399
5. Water for Injection 2 100 2 100
Manufacturing process:
Indocyanine green was dissolved in water for injection by stirring. Dispensed
quantities of Disodium hydrogen phosphate, Sodium dihydrogen phosphate and
Sodium chloride were added to the above solution and stirred. Further volume was
adjusted to 100% with remaining quantity of water for injection. The bulk solution
was filled into vials and loaded over precooled shelves of lyophilizer and subjected
for freeze drying. After completion of lyophilization process, vials were withdrawn,
stoppered and sealed. The lyophilized vials are packed into a kit comprising the
lyophilized product and a diluent vial.
The formulation of the above example (F3) was tested for stability in comparison
with the RLD Formulation. The data is presented in the following tables.
Table 1: Comparative stability data of F3 with RLD using water as diluent
Concentration 1.25mg/mL
Formulations F3 RLD
Time point Initial 6Hr 12Hr 24Hr Initial 6Hr 12Hr 24Hr
pH 7.00 6.86 6.87 6.90 7.25 7.05 7.19 7.16
Osmolality 22 24 16 24 17 19 15 17
Assay 100.5 100.1 99.6 99.0 94.9 91.6 89.3 87.4
% drop in assay 0.4 0.9 1.5 3.3 5.6 7.5
Total Impurities
(% w/w)
0.62 1.10 1.70 2.70 5.70 8.04 9.25 11.55
% increase in
Impurities
-- 0.48 1.08 2.08 -- 2.34 3.55 5.85
Concentration 5mg/mL
Formulations F3 RLD
Time point Initial 6Hr 12Hr 24Hr Initial 6Hr 12Hr 24Hr
pH 6.83 6.88 6.87 6.95 6.56 6.56 6.70 6.35
Osmolality 75 68 72 78 23 27 16 15
Assay 98.2 98.0 97.7 97.0 93.0 89.3 85.8 81.6
% drop in assay 0.2 0.5 1.2 3.7 7.2 11.4
Total Impurities
(% w/w)
0.72 1.02 1.30 1.73 6.15 8.42 10.29 13.54
% increase in
Impurities
-- 0.3 0.58 1.01 -- 2.27 4.14 7.398
Table 2: Comparative stability data of F3 with RLD using 0.45% Sodium chloride
as diluent
Concentration 1.25mg/mL
Formulation F3 RLD
Time point Initial 6Hr 12Hr 24Hr Initial 6Hr 12Hr 24Hr
pH 6.71 6.61 6.56 6.65 7.12 7.18 7.24 7.15
Osmolality 142 165 168 168 128 129 125 131
Assay 102.0 102.1 101.8 101.6 93.7 92.1 90.4 89.6
% drop in assay - 0.1 0.2 0.4 - 1.6 3.3 4.1
Total Impurities
(% w/w)
0.74 0.92 1.30 1.68 5.58 6.20 6.89 8.39
% increase in
Impurities
-- 0.18 0.56 0.94 -- 0.62 1.31 2.81
Concentration 5 mg/mL
Formulation F3 RLD
Time point Initial 6Hr 12Hr 24Hr Initial 6Hr 12Hr 24Hr
pH 6.65 6.59 6.62 6.64 6.62 6.64 6.23 6.36
Osmolality 196 220 203 206 128 132 127 146
Assay 99.2 98.8 98.9 98.7 93.5 91.8 90.4 87.7
% drop in assay - 0.4 0.3 0.5 - 1.7 3.1 5.8
Total Impurities
(% w/w)
0.70 0.71 1.06 1.37 5.98 6.64 7.56 9.67
% increase in
Impurities
-- 0.01 0.36 0.67
-- 0.66 1.58 3.69
The above data in Table 1, clearly shows exceptional improvement in stability in
F3 formulation when compared to the RLD. The drop in assay at a concentration of
1.25mg/mL is 1.5% in the inventor’s formulation when tested after 24 hours when
reconstituted with water, whereas at the corresponding time point, RLD showed a
drop of 7.5%. Similarly, at a concentration of 5mg/mL, the drop in assay is 1.2% in
the inventor’s formulation when tested after 24 hours when reconstituted with
water, whereas at the corresponding time point, the RLD showed a drop of 11.4%.
The increase in impurities is also significantly high in the RLD formulation. The %
increase in impurities is 2.08% in the inventor’s formulation and 5.85% in the RLD
formulation when tested after 24 hours after reconstituting with water. Similarly, at
a concentration of 5mg/ml, the % increase in impurities is 1.01% in the inventor’s
formulation and 7.39% in the RLD.9
Table 2 shows comparative stability data of F3 with RLD using 0.45% Sodium
chloride as diluent. The drop in assay at 1.25mg/mL, is 0.4% in the inventor’s
formulation when tested after 24 hours whereas at the corresponding time point, the
RLD shows a drop of 4.1%. Similarly, at a concentration of 5mg/mL, the drop in
assay is 0.5% in the inventor’s formulation when tested after 24 hours whereas at
the corresponding time point, the RLD shows a drop of 5.8%. This means that the
present formulation is at least 10 times more stable than the RLD.
The % impurities are also 3-5 times higher in the RLD formulation when tested
after 24 hours.
Significant improvement in stability of inventor’s formulation when compared to
RLD can be clearly seen from the below table:
Table 3: Comparison of drop in Assay values of F3 with RLD
Note: * Indicates number of folds, F3 formulation is more stable than RLD.
Drop in Assay
Water as Diluent
1.25 mg/mL 5 mg/mL
Formulations F3
Formulation
RLD
Formulation
F3
Formulation
RLD
Formulation
6Hr 0.4 3.3 0.2 3.7
12Hr 0.9 5.6 0.5 7.2
24Hr 1.5 7.5 1.2 11.4
5 folds* > 9 Folds*
0.45% Sodium chloride as Diluent
1.25 mg/mL 5 mg/mL
Formulations F3
Formulation
RLD
Formulation
F3
Formulation
RLD
Formulation
6Hr 0.1 1.6 0.4 1.7
12Hr 0.2 3.3 0.3 3.1
24Hr 0.4 4.1 0.5 5.8
> 10 folds* > 11 folds*10
Table 4: Comparison of increase in Impurities values of F3 with RLD
Note: * Indicates number of folds decrease in impurities value of F3 when compared
to RLD.
Example 3:
S. No Ingredients
F4 F5
mg/mL % w/v mg/mL % w/v
1. Indocyanine Green 25 1.25 25 1.25
2. Disodium Hydrogen phosphate 3.36 0.168 4.93 0.2465
3. Sodium dihydrogen phosphate 3.36 0.168 4.93 0.2465
4. Sodium Chloride 11.04 0.552 16.18 0.809
5. Water for Injection
Q.S.
2.0 mL
100
Q.S.
2.0 mL
100
Manufacturing process:
Indocyanine green was dissolved in water for injection by stirring. Dispensed
quantities of Disodium hydrogen phosphate, Sodium dihydrogen phosphate and
Sodium chloride were added to the above solution and stirred. Further volume was
Increase in Impurities
Water as Diluent
1.25 mg/mL 5 mg/mL
Formulations F3
Formulation
RLD
Formulation
F3
Formulation
RLD
Formulation
6Hr 0.48 2.34 0.3 2.27
12Hr 1.08 3.55 0.58 4.14
24Hr 2.08 5.85 1.01 7.39
> 2 folds* > 7 folds*
0.45% Sodium chloride as Diluent
1.25 mg/mL 5 mg/mL
Formulations F3
Formulation
RLD
Formulation
F3
Formulation
RLD
Formulation
6Hr 0.18 0.62 0.01 0.66
12Hr 0.56 1.31 0.36 1.58
24Hr 0.94 2.81 0.67 3.69
> 2 folds* > 5 folds*11
adjusted to 100% with remaining quantity of water for injection. The bulk solution
was filled into vials and loaded over precooled shelves of lyophilizer and subjected
for freeze drying. After completion of lyophilization process, vials were withdrawn,
stoppered and sealed. The lyophilized vials are packed into a kit comprising the
lyophilized product and a diluent vial. 12
We Claim
Claim 1: A parenteral solution of indocyanine green comprising lyophilized powder
of indocyanine green dissolved in a diluent, wherein the said solution is stable for
up to 24 hours after reconstitution.
Claim 2: The solution of claim 1 that is free of alcohol and polysorbate.
Claim 3: The solution of claim 1, wherein the lyophilized powder further comprises
disodium hydrogen phosphate, sodium dihydrogen phosphate.
Claim 4: The solution of claim 1, wherein the lyophilized powder comprises 1-10%
w/v indocyanine green; 0.05% w/v - 0.5% w/v disodium hydrogen phosphate and
0.05% w/v - 0.5% w/v sodium dihydrogen phosphate.
Claim 5: The solution of claim 1, wherein the diluent is selected from the group
comprising water for injection, 0.9% Sodium chloride, 0.45% Sodium chloride.
Claim 6: The solution of claim 1, wherein the drop in assay is not more than 10%
when stored at 25°C for 24 hours.
Claim 7: The solution of claim1, wherein the total impurities is not more than 5%
when stored at 25°C for 24 hours. STABLE FORMULATIONS OF INDOCYANINE GREEN
Abstract
The present invention relates to a stable, alcohol-free formulations of indocyanine
green. These indocyanine green formulations are lyophilized and further comprise
of indocyanine green and other optional excipients that are stable up to 24hrs even
after reconstitution with diluent solution. Further, the present invention also
describes process of preparing such stable parenteral formulations of indocyanine
green.