WO2016079749A2

WO2016079749A2 - Process for preparation of parenteral formulation of anidulafungin

Info

Publication number: WO2016079749A2
Application number: PCT/IN2015/000349
Authority: WO
Inventors: Mitesh Natavarlal PATEL; Mafatlal Tribhovandas DAVE; Pranavkumar Jayesh CHOKSI
Original assignee: Gufic Biosciences Limited
Priority date: 2014-11-19
Filing date: 2015-09-07
Publication date: 2016-05-26
Also published as: EP3220954A2; WO2016079749A3; EA201791100A1; EP3220954A4; ZA201703330B

Abstract

The present invention discloses a freeze dried, micelle-forming surfactant free pharmaceutical formulation of anidulafungin along with a suitable solubilizing agent and acidifying agent for parenteral administration. The pharmaceutical formulation provides sufficient solubilization and stabilization of anidulafungin thus improving the shelf life and reduces the likelihood of precipitation during storage. The invention further discloses a process of preparation thereof.

Description

PROCESS FOR PREPARATION OF PARENTERAL FORMULATION OF

ANIDULAFUNGIN"

Field of invention:

The present invention relates to freeze dried, micelle-forming surfactant free pharmaceutical formulation of Anidulafungin along with a suitable solubilizing agent and acidifying agent for parenteral administration. The pharmaceutical formulation provides sufficient solubilisation and stabilization of Anidulafungin thus improving the shelf life and reduces the likelihood of precipitation during storage. The invention further relates to a process of preparation thereof.

Background of the invention:

Invasive fungal infections are a major and growing cause of morbidity and mortality in immune compromised patients such as patients with HIV/AIDS infection, those with hematologic malignancies (eg, leukemia, lymphoma), those with solid tumors, or among patients undergoing solid-organ, bone marrow, or hematopoietic stem cell transplantation, or who have been exposed to high-dose corticosteroids. The' epidemiology of invasive fungal infections has also changed substantially. Although Candida species still cause the majority of fungal infections among all compromised hosts, in many tertiary care institutions that care for transplant recipients or patients with hematologic malignancies, Aspergillus is also found to cause morbidity and mortality in patients.

Conventional agents, such as Amphotericin B and the azole antifungals, present tolerability issues. Renal toxicity is a major concern with amphotericin B, while drug- drug interactions, hepato toxicity, and skin rashes are the primary concerns with the azole medications.

Recently, a new class of antifungals, the echinocandins, has been developed. These agents interfere with cell wall biosynthesis by non-competitive inhibition of 1, 3-d-glucan Synthase; an enzyme present in fungi but absent in mammalian cells (Walsh et al., 2000; Ernst, 2001). They are used to treat a variety of fungal infections, including invasive infections due to either Candida or Aspergillus. These antifungals have shown clinical efficacy and a more favourable adverse-event (AE) profile compared with those of conventional antifungal agents.

Anidulafungin is a semi synthetic lipopetide in the echinocandin class of antifungal drugs, which is administered intravenously to treat mucosal and invasive fungal infections. (Jose A. Vazquez, MD, Clinical Therapeutics/Volume 27, Number 6, 2005). Chemically, Anidulafungin is N-[(3S,6S,9S,l lR,15S,18S,20R,21R,24S,25S,26S)-6-[(lS,2R)-l,2- dihydroxy-2-(4-hydroxyphenyl)ethyl]-l l,20,21,25-tetrahydroxy-3,15-bis[(lR)-l- hydroxyethyl]-26-methyl-2,5,8, 14, 17,23-hexaoxo- 1 ,4,7, 13,16,22-hexaaza tricycle [22.3.0.09,13]heptacosan-18-yl]- 4-{4-[4-(-(pentyloxy)phenyl]phenyl}benzamide)(Fig l)is insoluble in water with a pKa of 9.46. The solubility of Anidulafungin decreases further strongly when the pH is below 4.

Fig l

Anidulafungin is marketed as lyophilized product for intravenous infusion by Pfizer under the trade name Eraxis. Anidulafungin is indicated for the treatment of oesophageal candidiasis, candidemia, and other invasive Candida infections including intra-abdominal abscess and peritonitis. Currently available formulations in lyophilized vial contain micelle-forming surfactant which does not provide a freeze-dried product with desirable characteristics due to the sensitivity of surfactant against freeze drying. The presence of the surfactant causes the freeze-dried cake to "collapse" resulting in a residue at the bottom of the vial instead of a well-formed cake. The residue is generally less stable, difficult to reconstitute, and non-reproducible. (Carpenter et al., Pharm. Res., 14 (8), 969- 975, 1977 to 1997, Physicians" Desk Reference 50"' edition, Medical Economics Co. NJ

(1996)). Further, Anidulafungin is sensitive to chemical degradation which limits the shelf-life of solutions in water and being insoluble in water is extremely dangerous to administer in parenteral state.

US6960564 discloses a freeze-dried formulation comprising anidulafungin, or a pharmaceutically acceptable salt thereof; a micelle-forming surfactant in an amount greater than 5% by weight which is selected from a polysorbate, a polyoxyethylene castor oil derivative, a polyoxyethylene stearate or combinations thereof; a bulking agent selected from mannitol, sucrose, trehalose, lactose, or mixtures thereof; and stabilizing agent comprising sucrose, fructose, trehalose or mixtures thereof. However, it appears that the products demonstrated in US'564 appear to be not stable (tables 3 & 4) in view of the increase in related substances over the period of 3 to 4 weeks.

Cyclodexrtin and their derivatives are known generally to improve the dissolution rate of drugs and find applications in pharmaceutical delivery systems. As a "host" for "guest" drug molecules, the complexes show increased aqueous solubility for pharmaceuticals with intrinsically low aqueous solubility resulting in the improved bioavailability of the drug. The use of cyclodextrin for increasing the solubility of azole antifungals are known, however, the prior art is silent on use of cyclodextrin for increasing the solubility of Anidulafungin.

In view of the poor solubility . of Anidulafungin and the other shortcomings such as stability in preparing the lyophilized product for parenteral administration as mentioned above, the present inventors felt a need to provide a more stable Anidulafungin Injectable formulation which is micelle forming surfactant free, enhances the bioavailability of the drug, increases shelf life and also patient compliant.

Summary of the invention:

In accordance with above, the present invention provides freeze dried, micelle-forming surfactant free pharmaceutical formulation of anidulafungin or pharmaceutically acceptable salt thereof along with a suitable solubilizing agent and acidifying agent for parenteral administration. The solubility of Anidulafungin is increased by adding solubilizing agents selected from modified cyclodextrin derivatives such as hydroxypropylbetadex, sulfobutyl ether betacyclodextrin sodium or Tris buffer Hydrochloride salt.

The solubilizing agent is present in an amount in the ratio of 1 :20 to 1 :100, preferably 1 :62, more preferably 1 :44 by weight of the active.

The pH of the formulation is maintained in the range of 3 to 7, preferably between 4 to 6, more preferably between 4.0 and 5.5 using acidifying agents selected from organic acids such as Succinic acid, acetic acid, citric acid, tartaric acid, lactic acid or inorganic acid such as hydrochloric acid.

In an aspect, the pharmaceutical composition of Anidulafungin, solubilizing agent and an acidifying agent is freeze dried and is provided as a drug concentrate.

In another aspect, the present invention provides a method for increasing solubility of anidulafungin in an aqueous solution.

Detailed description of the invention:

The invention will now be described in detail in connection with certain preferred and optional embodiments, so that various aspects thereof may be fully understood and appreciated.

Anidulafungin is an uncrystalline powder with a pKa of 9.46 and is insoluble in water. The solubility of Anidulafungin decreases further strongly when the pH is below 4. However, it is observed by the current inventors that it is possible to provide stable pharmaceutically acceptable composition/formulation for parenteral administration or intravenous infusion comprising of Anidulafungin as the active using a suitable solubilizer such as modified cyclodextrin derivatives or Tris buffer and maintaining appropriate pH of the formulation.

In an embodiment, the present invention relates to freeze dried, micelle forming surfactant free pharmaceutical composition for parenteral administration comprising; Anidulafungin or a pharmaceutically acceptable salt thereof,

a pharmaceutically acceptable solubilizing agent, and

an acidifying substance.

Anidulafungin or a pharmaceutically acceptable salt is present in the composition in an amount from 1 mg to 100 mg/vial; more preferably 50mg/vial and lOOmg/vial.

The solubility of Anidulafungin is increased using a suitable solubilizing agent where Anidulafungin can be maintained in a dissolved state in the aqueous solution thereby preventing crystallization or crystalline growth of Anidulafungin. The solubilizing agent is selected from modified cyclodextrin derivatives such as hydroxypropylbetadex, sulfobutyl ether betacyclodextrin sodium or Tris buffer Hydrochloride salt.

The solubilizing agent is present in an amount in the ratio of 1 :20 to 1 :100, preferably 1 :62, more preferably 1 :44by weight of the active.

The pH of the formulation is maintained in the range of 3 to 7, preferably between 4 to 6, more preferably between 4.0 and 5.5 using acidifying agent selected from organic acid such as succinic acid, acetic acid, citric acid, tartaric acid, lactic acid or inorganic acid such as hydrochloric acid.

Such composition after freeze drying is chemically and physically stable over an extended period of time and is suitable for intended pharmaceutical use after reconstitution with water for injection, sodium chloride injection or 5% dextrose injection which is represented in the examples below.

The aqueous intravenous composition of the invention may also comprise a physiologically and pharmaceutically acceptable compound effective to render the aqueous intravenous composition isotonic, i.e. to have an osmotic pressure corresponding to that of a 0.9% solution of sodium chloride. Typical examples of such compounds are chloride salts such as NaCl and saccharide such as sorbitol, mannitol and dextrose/glucose. The preparation of isotonic solutions is well known for one skilled in the art. The diluents suitable for the purpose of present invention include 5% Dextrose, 5% Glucose, Ringers solution, Lactated Ringers solution, saline solution and half normal saline.

In another embodiment, the present invention provides a method of increasing solubility of Anidulafungin in an aqueous solution comprising the step of combining Anidulafungin aqueous solution with a solubilising agent and an acidifying agent. Alternately, adding solubilizing agent and an acidifying agent to the aqueous solution of Anidulafungin. The solubilizing agent being the pharmaceutically acceptable solubilizing agent selected from modified cyclodextrin derivatives such as hydroxypropylbetadex, sulfobutyl ether betacyclodextrin sodium or Tris buffer Hydrochloride salt; preferably Hydroxypropylbetadex. The acidifying agent is selected from organic acid such as succinic acid, acetic acid, citric acid, tartaric acid, lactic acid or inorganic acid such as hydrochloric acid, preferably tartaric acid or 0. IN hydrochloric acid. Depending on final desired concentration of Anidulafungin, the pH of aqueous composition is fixed such that the drug is sufficiently solubilized to achieve the desired concentration before reconstitution with suitable vehicle/solvent.

In another embodiment, the present invention provides a method of increasing solubility of Anidulafungin in an aqueous solution comprising, adding 22% solution of Hydroxypropylbetadex as solubilizing agent and 0.1 N solution of hydrochloric acid as acidifying agent to the aqueous solution of Anidulafungin.

In yet another embodiment, the invention provides a process for preparation of pharmaceutical composition, in particular for intravenous infusion, comprising Anidulafungin or a pharmaceutically acceptable salt thereof as the active ingredient, a pharmaceutically acceptable solubilizing agent, acceptable acidifying agent. Accordingly, Anidulafungin or pharmaceutically acceptable salt thereof initially is solubilized in an aqueous solution containing solubilizing agent, preferably in the ratio 1 :44 followed by addition of acidifying agent, preferably 0.1 N Hydrochloric acid to adjust pH of solution to an acceptable level of range between 4.0- 5.5 followed by filtration from 0.22 micron filter paper. The filtrate is then freeze dried to render it sterile and filling 10 ml quantity of filter solution in sterile glass container of 20 ml vial size. The formulation of the current invention is meant for administration via the IV route, the selection of the above ingredients is done keeping in mind their compatibilities and stability during the rigorous process for lyophilization and also in terms of safety for use in patients as an intravenous injectable which is isotonic with blood tonicity.

Moreover, for intravenous pharmaceutical aqueous solution to be administrable to a patient, the active ingredient of the composition needs to be dissolved sufficiently in the composition i.e. be free from visible particles. To achieve this, freeze dried/lyophilized powder is used to obtain clear colourless solution, free from visible particles.

Freeze drying process involves cooling of product at suitable temperature not less than - 50°C, raising temperature to 0°C at suitable pressure of 200 mtorr to 100 mtorr in 45 hours, then at 75 mtorr, further raising temperature to +15°C in 22 hrs.

The freeze dried Anidulafungin when reconstituted with 15 ml of suitable vehicle contains final drug concentrate of 3.33 mg/ml.

In another embodiment, the pharmaceutical composition of the invention described herein is freeze dried composition, which may also be prepared by dissolving Anidulafungin first in aqueous vehicle containing solubilizing agent then adjusting pH to desired range using acidifying agent.

Developing freeze drying process for such a low soluble active ingredient needs special care and it is an art in its own way because of low concentration of solute (about 0.5%) and maximum amount of aqueous vehicle e.g. water for injection. The freeze dried drug may be diluted with suitable diluent before administration as IV injection. The final concentration of solution may be reduced to further desired level using 5% Dextrose infusion prior to administration to a patient.

In a further embodiment, the invention provides a method of treating or preventing an infection caused by a fungus or a parasite in an animal in need thereof which comprises administering to said animal an effective amount of the pharmaceutical composition of the instant invention. In another embodiment, the present invention relates to the use of anidulaiungin parenteral formulation for treating or preventing an infection caused by a fungus or a parasite in an animal in need thereof.

The pharmaceutical compositions of the present invention are administered to a patient according to a dosing regimen. It should be understood that the specific dosing regimen for any particular patient will depend on a variety of factors, including age, body weight, general health, sex, diet, time of administration, specific disease being treated, and the severity of the condition among other factors and the judgment of the treating physician. Other features and embodiments of the invention will become apparent by the following examples which are given for illustration of the invention rather than limiting its intended scope. Various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art.

Experimental:

Several different trials were conducted and tested before narrowing down to the present formulation. Some of these trials are discussed in brief below to emphasize the inventiveness of the current invention.

Example: 1

Anidulaiungin (active) or pharmaceutically acceptable salt was added to an aqueous solution containing pre-decided quantity of Kollidon PF 12 and stirred for some time. Solution was further sonicated. The solution was divided in to 4 equal parts.

To part one drop by drop 5% citric acid solution was added but Anidulafungin did not dissolve in it and remained as undissolved particles.

To second part drop by drop 5% Tartaric acid solution was added but Anidulafungin did not dissolve in it and remained as undissolved particles.

To third part drop by drop 5% Acetic acid solution was added but Anidulafungin did not dissolve in it and remained as undissolved particles. To fourth part drop by drop 1% Hydrochloric acid solution was added but Anidulafungin did not dissolve in it and remained as undissolved particles.

Since product showed undissolved particles, no further testing was done.

Example: 2

In another trial, Anidulafungin (active) or pharmaceutically acceptable salt was added to an aqueous solution containing pre-decided quantity of Kollidon PF 12 and stirred for some time. Solution was further sonicated. To this solution 1% sodium hydroxide solution was added drop wise but the resulting clear solution changed color and assay of active went down and out of specifications when measured by spectrophotometer.

Assay: 15.75%

Example: 3

To a 2% solution of Tris buffer hydrochloride salt in water, calculated quantity of Anidulafungin was added, Suspension was sonicated.

It was divided into two parts.

To part one drop by drop O. lNHydrochloric acid solution was added to observe if Anidulafungin dissolved. Only, minor quantity of Anidulafungin remained as undissolved particles.

To Second part drop by drop IN sodium hydroxide solution was added which dissolved Anidulafungin at pH 10 but it rendered solution colored and assay of active went down to 10% measured on spectrophotometer.

Example: 4

In Anidulafungin plus water, 1 -50 times (weight of Anidulafungin) powder of Disodium phosphate was added but the active remained partially insoluble and rendered the solution coloured.

So no assay was done. Example: 5

In Anidulafungin plus water, 1-20% This buffer was added dropwise but the active remained insoluble.

So no assay was done.

Example: 6

In Anidulafungin plus water, 1% Trisodium citrate solution was added drop wise but the active remained insoluble.

So no assay was done.

Example: 7

In Anidulafungin plus water, 1-2% kollidon PF 12 solution was added drop wise but the active remained insoluble.

So no assay was done.

Example: 8

Like -wise other pre-formulation trials were checked with organic alkaline agent like either mono ethanolamine or triethanolamine and it was observed that the products were either getting solubilized partly or forming colored solution or assay was getting reduced to 10 to 15%.

Example 9:

Suitable trial was done using micelle forming surfactant like Polysorbate 80 to dissolve active product Anidulafungin in aqueous base along with suitable acidifying agent like tartaric acid and isotonic agent like mannitol, to check and compare solubility and stability of liquid preparation. Accordingly following process was followed:

Ingredients Qty. per vial

Anidulafungin 50 mg 20ml USP type I glass vial were used

Fructose 50mg elastomeric stopper (Grey bromobutyl rubber stopper)

Tartaric acid 5.6 mg

* 10% Overages of active content

Mannitol 250 mg Polysorbate 80 125 mg added.

Dissolved Polysorbate 80, Mannitol, Tartaric acid & Fructose in water for injection. Added Anidulafungin and stirred to dissolve. Filtered, filled 5 ml in each vial and lyophilized it. The results are described in Table 1 herein below:

Table!:

Conclusion: The product was stable for 6 months at 25°C and for 9 months at 2 - 8°C.

Example 10:

The similar trial as in example 9 was taken without using fructose.

Ingredients Qty. per vial

Anidulafungin 50 mg 20ml USP type I glass vial were used

Tartaric acid 5.6 mg elastomeric stopper (Grey Mannitol 250 mg bromobutyl rubber stopper)

Polysorbate 80 125 mg * 10% Overages of active content added.

Dissolved Polysorbate 80, Mannitol, and Tartaric acid in water for injection. Added Anidulafungin and stirred to dissolve. Filtered, filled 5 ml in each vial and lyophilized it. The results are described in Table 2 herein below:

Table 2:

Conclusion: The product was not stable after 3 months at 25°C and 2-8°C, due to increase in impurity.

Example 11:

Suitable trial was done using solubilizer Hydroxypropylbetadex to dissolve active product Anidulafungin in aqueous base along with suitable acidifying agent like 0.1N Hydrochloric acid, to check and compare solubility and stability of liquid preparation. Accordingly following process was followed:

Ingredients Qty. per ml

Anidulafungin 5mg

Hydroxypropylbetadex 100 mg 0.1 N Hydrochloric acid q.s. to pH 4.5

Dissolved Hydroxypropylbetadex in water for injection. Added Anidulafungin and stirred to dissolve and adjusted pH with 0.1 N Hydrochloric acid.

Conclusion: Drug was not completely solubilized.

Example 12:

Suitable trial was done using solubilizer, Hydroxypropylbetadex to dissolve active product Anidulafungin in aqueous base along with suitable acidifying agent like 0.1N Hydrochloric acid, to check and compare solubility and stability of liquid preparation. Accordingly following process was followed:

Dissolved Hydroxypropylbetadex in water for injection. Added Anidulafungin and stirred to dissolve, adjusted pH with 0.1 N Hydrochloric acid.

Conclusion: Drug was not completely solubilized.

Example 13:

Suitable trial was done using Solubilizer, Hydroxypropylbetadex to dissolve active product Anidulafungin in aqueous base along with suitable acidifying agent like 0.1 N Hydrochloric acid, to check and compare solubility and stability of liquid preparation. Accordingly following process was followed:

Ingredients Qty. per ml

Anidulafungin 5mg

Hydroxypropylbetadex 160 mg

0.1 N Hydrochloric acid q.s. to pH 4.5 Dissolved Hydroxypropylbetadex in water for injection. Added Anidulafungin and stirred to dissolve. Adjusted pH with 0.1 N Hydrochloric acid.

Conclusion: Drug was not completely solubilized.

Example 14:

Suitable trial was done using solubilizer, Hydroxypropylbetadex to dissolve active product Anidulafungin in ratio of 1 : 100 in aqueous base along with suitable acidifying agent like 0.1N hydrochloric acid, to check and Compare solubility and stability of liquid preparation. Accordingly foMowing process was followed:

Dissolved Hydroxypropylbetadex in water for injection. Added Anidulafungin and stirred to dissolve, adjusted pH with 0.1 N Hydrochloric acid, clear solution resulted, testing was done using UV absorption spectra.

Bulk Assay:99.15%

Example 15:

Suitable trial was done using Solubilizer, Hydroxypropylbetadex to dissolve active product Anidulafungin in ratio of 1 :62 in aqueous base along with suitable acidifying agent like 0.1 N Hydrochloric acid, to check and compare solubility and stability of liquid preparation. Accordingly following process was followed:

Dissolved Hydroxypropylbetadex in water for injection. Added Anidulafungin and stirred to dissolve, adjusted pH with 0.1 N Hydrochloric acid; testing was done using UV absorption spectra.

Bulk Assay : 99.11%. Example 16:

Suitable trial was done using solubilizer Hydroxypropylbetadex to dissolve active product Anidulafungin in ratio of 1 :44 in aqueous base along with suitable acidifying agent like 0.1 N Hydrochloric acid, to check and compare solubility and stability of liquid preparation. Accordingly following process was followed:

Dissolved Hydroxypropylbetadex in water for injection. Added Anidulafungin and stirred to dissolve adjust pH with 0.1 N Hydrochloric acid; testing was done using UV absorption spectra.

Bulk Assay:99.16%

Example 17:

To the solution of Hydroxypropylbetadex in water, Anidulafungin was dissolved. Solution was sonicated. The pH of above mentioned solutions was adjusted 4.0 to 5.5, more preferably between 4.2 - 4.7, Solution was diluted with water to desired concentration and was filtered from 0.22 micron filter paper. The solution was filled individually in glass vials of suitable size or filled in a sterile tray and subjected to a cycle of Lyophilization to obtain unit lyophilized vials or lyophilized powder ready to be filled directly in vials. The lyophilized powder was diluted further with 15ml water for injection.

This study was further linked up with solution stability studies at pre-formulation stage. Accordingly these examples were repeated quantitatively and testing was done using

HPLC.

Ingredients , Qty. per ml

Anidulafungin 5 mg 20ml USP type I glass vial used.

Hydroxypropylbetadex 220 mg 10ml filled volume.

0.1 N Hydrochloric q.s. to pH 4.5 10ml solution filled in each vial acid (Limit: 4.0 to 5.5) Grey bromo butyl plugs were Water for injection To make 1ml used with full slotted pH 4.49 For freeze-drying

Bulk Assay 108.13% * 10% Overages of active content

Impurities Single max. Impurity: 0.19% added.

Total Impurities: 0.39%

Table 3: Results of stability study at 2-8°C and 25°C are given below:

Conclusion: The product was stable for an observed period of 6 months at 25°C and for observed period of 9 months at 2 - 8°C.

For process validation further two trials were taken on similar line of Example 17 and results are summarized in tabular form as follow as Example 18 & Example. 19.

Results are summarized in tabular form as follows: Example: 18

Table 4: Results of stability study at 2-8°C and 25°C are given below:

Example: 19

Table 5: Results of stability study at 2-8°C and 25°C are given below:

Period Assay pH Single. Total Storage Color

(%) impurity impurity temp.

(%) (%)

Initial 108.97 4.45 0.31 0.57 2-8°C White

lyophilized cake

After 3 months 108.43 4.44 0.39 0.68 2-8°C White

lyophilized cake

107.81 4.43 0.49 0.78 25°C White

lyophilized cake After 6 months 108.12 4.45 0.43 0.69 2-8°C White

lyophilized cake

106.93 4.44 0.61 0.91 25°C White

lyophilized cake

After 9 months 106.11 4.46 0.52 0.78 2-8°C White

lyophilized cake

The freeze dried product so obtained dissolved easily in 15ml water for injection, to form clear colourless solution.

In summary, the present invention provides water soluble Anidulafungin as freeze dried stable formulation, stable for 6 months, when stored at 25°C.

Industrial Advantages:

1. The pharmaceutical composition comprising anidulafungin as active is free from micelle forming surfactants such as polysorbates, lecithin, bilesalts, polyoxyethylene, castor oils and mixtures thereof without compromising solubility of drug and whose solution before Lyophilization has a pH between 4.0 to 5.5.

2. The formulation is stable for the entire period of the shelf life.

Claims

We claim,

1. Surfactant free, stable, freeze dried pharmaceutical compositions of anidulafungin for parenteral administration, which comprises;

i. Anidulafungin or a pharmaceutically acceptable salt thereof in an amount 1 mg to lOO mg/vial;

ii. a pharmaceutically acceptable modified cyclodextrin derivatives selected from hydroxypropylbetadex or sulfobutyl ether betacyclodextrin sodium as solubilizing agent, and

iii. a pharmaceutically acceptable acidifying substance;

wherein the modified cyclodextrin derivative is in the ratio of 1 :20 to 1 :100 by weight of the active and wherein, pH of said composition is in the range of 4.0 to 5.5.

2. The pharmaceutical composition according to claim 1, wherein the modified cyclodextrin derivative is in the range of 1 :62 by weight of the active.

3. The pharmaceutical composition according to claim 1, wherein the modified cyclodextrin derivative is in the range of 1 :44 by weight of the active.

4. The pharmaceutical composition according to claim 1 , wherein the acidifying agent is an organic acid selected from succinic acid, acetic acid, citric acid, tartaric acid, lactic acid or inorganic acid such as hydrochloric acid.

5. The pharmaceutical composition according to any one of the preceding claims, wherein the modified cyclodextrin derivative is Hydroxypropylbetadex.

6. A method of increasing solubility of Anidulafungin or a pharmaceutically acceptable salt in an aqueous solution, comprising a step of combining Anidulafungin or a pharmaceutically acceptable salt thereof with modified cyclodextrin derivatives or with a Tris buffer hydrochloride salt and an acidifying agent.

7. The method of increasing solubility according to claim 6, wherein, the modified cyclodextrin derivatives are selected from hydroxypropylbetadex and sulfobutyl ether betacyclodextrin sodium.

8. Surfactant free, stable freeze dried pharmaceutical composition for parenteral administration, which comprises;

i. Anidulafungin or a pharmaceutically acceptable salt thereof in an amount of lmg to 100 mg/vial;

ii. Hydroxypropylbetadex in aqueous solution as a solubilizing agent; and iii. 0. IN hydrochloric acid as acidifying agent;

wherein the Hydroxypropylbetadex is in the ratio of 1 :20 to 1 :100 by weight of the active and wherein, pH of said composition is in the range of 4.0-5.5.

9. Surfactant free, stable, freeze dried pharmaceutical composition for parenteral administration according to claim 1 comprising Tris buffer hydrochloride as solubilizing agent.