DESC:FIELD OF THE INVENTION

The present invention provides a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, for use in the treatment of actinic keratosis and other skin diseases. Further, the present invention provides a process for the preparation of the said composition.

BACKGROUND OF THE INVENTION

5-Fluorouracil is thymidylate synthase (TS) inhibitor, which is chemically 5-Fluoro-1H, 3H-pyrimidine-2,4-dione. The empirical formula of 5-Fluorouracil is C4H3FN2O2 and it has the structural formula (I).

(I)

5-Fluorouracil (5-FU) is sold under the brand name as Adrucil® Injection and Efudex® Cream. By injection into a vein, it is used for colon cancer, esophageal cancer, stomach cancer, pancreatic cancer, breast cancer, and cervical cancer. As a cream, it is used for actinic keratosis, basal cell carcinoma, and skin warts. Efudex® Cream is stored at 25° C; excursions permitted to 15°C to 30°C.

Calcipotriol, also known as calcipotriene, is a synthetic derivative of calcitriol, a form of vitamin D, which is chemically (1R,3S,5E)-5-{ 2-[(1R,3aS,4Z,7aR)-1-[(2R,3E)5-cyclopropyl-5-hydroxypent-3-en-2-yl]-7amethyl-octahydro-1H-inden- 4-ylidene]ethylidene}-4-methylidenecyclohyytyexane-1,3-diol. The empirical formula of Calcipotriol is C27H40O3 and it has the structural formula (II).

(II)

Calcipotriol is sold under the trade name Dovonex® in the United States, Daivonex® outside North America, and Psorcutan® in Germany. It is used in the treatment of psoriasis. It is safe for long-term application in psoriatic skin conditions. Dovonex® is stored at controlled room temperature 15° C to 25° C.

The US Patent No. US7169401 discloses a skin hydrating cream base consisting essentially of a hypoallergenic peanut oil, and an active ingredient, wherein said the active ingredient is fluorouracil.

The US Patent No. US6670335 discloses an oil-in-water emulsion formulation containing fluorouracil suitable for topical administration, and is useful for the treatment of solar keratosis, actinic keratosis, and superficial basal cell carcinoma.

The PCT Patent application No. WO2016040638 discloses compositions and methods for the treatment of precancerous skin lesions. The compositions of the invention comprise 5-fluorouracil (5-FU) and a vitamin D analog. The combined use of 5-FU and calcipotriol results in significantly higher clearance of actinic keratosis as compared to standard of care treatment (5-FU+Vaseline). However, there is no guidance on how to prepare a stable composition comprising 5-FU and calcipotriol. Further, the patent specification does not provide any reference related to a stable composition comprising 5-FU and calcipotriol.

The combination therapy has proved to be a preferred solution to improve patient’s adherence when a treatment requires the co-administration of drugs. Additionally, the combination therapy can reduce the costs of production and distribution of the treatment. However, in many cases, the design of a combination proves difficult for the reason such as chemical incompatibility between the different active ingredients or difficulties for co-formulating active ingredients to be administered with different release.

Although 5-FU and calcipotriol are available as cream compositions, when the combination is prepared by mixing the individual drug compositions, the assay of calcipotriol gets reduced, and therefore a stable combination product cannot be obtained by physical mixing of the individual drugs. Hence, there exists a need for a stable fixed-dose combination product containing such active ingredients which may not give rise to degradation of the active ingredients. The inventors of the present invention have developed a new stable fixed-dose topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, for use in the treatment of actinic keratosis and other skin diseases.

OBJECT OF THE INVENTION

The main object of the present invention is to provide a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof.

Another object of the present invention is to provide a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, wherein the said composition is a cream, an ointment, or a lotion.

Another object of the present invention is to provide a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, and at least one pharmaceutically acceptable excipient, wherein the pH of the said composition is more than 7.

Another object of the present invention is to provide a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof and at least one pharmaceutically acceptable excipient, wherein the pH of the said composition is from 7 to 9.

Another object of the present invention is to provide a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof and at least one pharmaceutically acceptable excipient, wherein the pH of the said composition is from 7 to 9 and further comprising a chelating agent.

Another object of the present invention is to provide a stable topical cream comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, and at least one pharmaceutically acceptable excipient selected from an emollient, an emulsifying agent, an ointment base, a chelating agent, a preservative, an antioxidant, a buffering agent, a humectant, a penetration enhancer and a solvent.

Another object of the present invention is to provide a process for preparation of stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, wherein the said composition is a cream, an ointment, or a lotion.

Another object of the present invention is to provide a process for preparation of stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, wherein the said composition is a cream prepared by mixing the components of the water phase and the wax phase.

Another object of the present invention is to provide a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, wherein the individual assay of 5-Fluorouracil and Calcipotriol in the said composition is at least 95% when stored at 25 °C / 60% RH for at least one month.

Another object of the present invention is to provide a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, wherein the total impurity in the said composition is not more than 5% when stored at 25 °C / 60% RH for at least one month.

Another object of the present invention refers to an aluminum collapsible tube packaging container comprising a stable topical cream comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof.

Another object of the present invention is to provide a stable topical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, for human administration for the treatment of actinic keratosis, precancerous skin lesions and other skin diseases.

SUMMARY OF THE INVENTION

In a first embodiment, the present invention relates to a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof.

In another embodiment, the present invention relates to a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, wherein the said composition is a cream, an ointment, or a lotion.

In another embodiment, the present invention relates to a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof with at least one pharmaceutically acceptable excipient, wherein the pH of the said composition is more than 7.

In another embodiment, the present invention relates to a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof and at least one pharmaceutically acceptable excipient, wherein the pH of the said composition is from 7 to 9.

In another embodiment, the present invention relates to a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof and at least one pharmaceutically acceptable excipient, wherein the pH of the said composition is from 7 to 9 and further comprising a chelating agent.

In another embodiment, the present invention relates to a stable topical cream comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, and pharmaceutically acceptable excipients selected from an emollient, an emulsifying agent, an ointment base, chelating agent, preservative, antioxidant, buffering agent, humectant, penetration enhancer and solvent.

In another embodiment, the present invention relates to a stable topical cream comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, and the following pharmaceutically acceptable excipients: cetostearyl alcohol, petrolatum, liquid paraffin, dichlorobenzyl alcohol, dl-a tocopherol, ceteth-20®, disodium hydrogen phosphate dihydrate, disodium edetate, glycerin, and sodium hydroxide and purified water.

In another embodiment, the present invention relates to a process for preparation of stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, wherein the said composition is a cream prepared by mixing the components of the water phase and the wax phase.

In another embodiment, the present invention relates to a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, wherein the individual assay of 5-Fluorouracil and Calcipotriol in the said composition is at least 95% when stored at 25 °C / 60% RH for at least one month.

In another embodiment, the present invention relates to a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, wherein the total impurity in the said composition is not more than 5% when stored at 25 °C / 60% RH for at least one month.

In another embodiment, the present invention relates to a stable topical composition comprising 2.5% w/w of 5-Fluorouracil and 0.0025% w/w of Calcipotriol or pharmaceutically acceptable salts thereof, wherein the pH of the said composition is from 7 to 9, and total impurity in the said composition is not more than 5% when stored at 25 °C / 60% RH for at least one month.

In another embodiment, the present invention relates to a stable topical composition comprising 5% w/w of 5-Fluorouracil and 0.0050% w/w of Calcipotriol or pharmaceutically acceptable salts thereof, wherein the pH of the said composition is from 7 to 9, and total impurity in the said composition is not more than 5% when stored at 25 °C / 60% RH for at least one month.

In another embodiment, the present invention relates to a stable topical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, wherein the said composition can be used for human administration for the treatment of actinic keratosis, precancerous skin lesions and other skin diseases.

DETAILED DESCRIPTION OF THE INVENTION

The detailed description and the examples provided herein are exemplary and any modification or variation within the scope of the invention will be apparent to a person skilled in the art. Further, unless otherwise defined, all the technical and scientific terms used herein shall bear the meaning as understood by a person who is ordinarily skilled in the art. Any ranges given herein include both the lower and the upper endpoints of the range. Furthermore, the present invention covers all possible combinations of particular and preferred embodiments described herein.

In one embodiment, the present invention provides a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, wherein the said composition is a cream, an ointment, or a lotion.

The term “stable pharmaceutical composition” of the present invention means the topical composition retains consistency as a white opaque cream and the individual assay of 5-Fluorouracil and Calcipotriol in the said composition is at least 95% when stored at 25 °C / 60% RH for at least one month, preferably for at least 2 months, and more preferably for at least 3 months. The abbreviation “RH” stands for relative humidity corresponding to the storage conditions. The individual assay of the active ingredient can be carried out by any conventional analytical methods, preferably by HPLC method. The HPLC (High-performance liquid chromatography) technique in analytical chemistry is used to separate, identify, and quantify each component in a mixture. The HPLC method is well known in the art for the quantification and qualification of analytes.

The impurities for Calcipotriol are characterized as follows:
Impurity B: (5Z,7Z,22E,24S)-24-cyclopropyl-9,10-secochola-5,7,10(19),22-tetraene-1a,3ß,24-triol ((7Z)-calcipotriol),
Impurity C: (5E,7E,22E,24S)-24-cyclopropyl-9,10-secochola-5,7,10(19),22-tetraene-1a,3ß,24-triol ((5E)-calcipotriol),
Impurity D: (5Z,7E,22E,24R)-24-cyclopropyl-9,10-secochola-5,7,10(19),22-tetraene-1a,3ß,24-triol (24-epi-calcipotriol).

In a preferred embodiment, the total impurity in the stable topical cream comprising 5-Fluorouracil and Calcipotriol is not more than 5% when stored at 25 °C / 60% RH for at least one month, as measured by HPLC method.

The active ingredients used in the stable composition comprises of 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof. In a preferred embodiment, the concentration of individual active ingredients or its pharmaceutically acceptable salt is from 0.001 to 20% w/w of the total composition. In one embodiment, the concentration of 5-Fluorouracil is from 1 to 10% w/w with respect to the total weight of the composition, and the concentration of Calcipotriol is from 0.001 to 0.01% w/w with respect to the total weight of the composition. In a preferred embodiment, the concentration of 5-Fluorouracil is 2.5 to 5 % w/w, and the concentration of Calcipotriol is 0.0025 to 0.0050 % w/w, with respect to the total weight of the composition.

In a preferred embodiment, the concentration of 5-Fluorouracil is 2.5 % w/w and the concentration of Calcipotriol is 0.0025 % w/w of the total composition. In a preferred embodiment, the concentration of 5-Fluorouracil is 5 % w/w and the concentration of Calcipotriol is 0.0050 % w/w of the total composition. Further, the amount of the active ingredients in the formulation can be varied that is within the scope of a person skilled in the art.

In another embodiment, the present invention provides a stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof and at least one pharmaceutically acceptable excipient, wherein the pH of the said composition is more than 7. In a preferred embodiment, the pH of the composition is from 7 to 9. In another preferred embodiment, the pH of the composition is from 7.2 to 8.8. In a more preferred embodiment, the pH of the composition is 8.5.

The stable composition of the present invention can comprise pharmaceutically acceptable excipients selected from an emollient, an emulsifying agent, an ointment base, chelating agent, preservative, antioxidant, buffering agent, humectant, penetration enhancer and solvent.

The emollient can be selected form the group consisting of aluminum monostearate, castor oil, cetostearyl alcohol, cyclomethicone, dimethicone, glycerin, glyceryl monooleate, glyceryl monostearate, isopropyl myristate, isopropyl palmitate, lecithin, mineral oil, lanolin alcohols, myristyl alcohol, petrolatum and sunflower oil. In a preferred embodiment, the emollient used in the stable topical cream comprising 5-fluorouracil and calcipotriol is cetostearyl alcohol.

The ointment base can be selected form the group consisting of lanolin, liquid paraffin, petrolatum, lanolin alcohols, polyethylene glycol, white petrolatum. In a preferred embodiment, the ointment base used in the stable topical cream comprising 5-fluorouracil and calcipotriol is petrolatum and liquid paraffin.

The chelating agent can be selected form the group consisting of calcium acetate, hydroxypropyl betadex, potassium citrate, citric acid, citric acid monohydrate, disodium edetate, sodium citrate dihydrate, dibasic sodium phosphate and tartaric acid. In a preferred embodiment, the chelating agent used in the stable topical cream comprising 5-Fluorouracil and Calcipotriol is disodium edetate (i.e. EDTA).

The antioxidant can be selected form the group consisting of dl-alpha tocopherol, ascorbic acid, ascorbyl palmitate, butylated hydroxyanisole, butylated hydroxytoluene, citric acid monohydrate, malic acid, methionine, potassium metabisulfite, propionic acid, propyl gallate, sodium ascorbate, sodium metabisulfite, sodium sulfite and sodium thiosulfate. In a preferred embodiment, the antioxidant used in the stable topical cream comprising 5-Fluorouracil and Calcipotriol is dl-alpha tocopherol.

The preservative can be selected form the group consisting of benzalkonium chloride, dichlorobenzyl alcohol, benzyl alcohol, boric acid, chlorhexidine, chlorobutanol, cresol, glycerin, hexetidine, potassium benzoate, potassium metabisulfite, potassium sorbate, propylene glycol, sodium acetate, sodium benzoate and thimerosal. In a preferred embodiment, the preservative used in the stable topical cream comprising 5-Fluorouracil and Calcipotriol is dichlorobenzyl alcohol.

The penetration enhancer can be selected form the group consisting of alcohol, dimethyl sulfoxide, ceteth-20®, polyoxyethylene alkyl ethers, docusate sodium, glyceryl monooleate, lauric acid, myristyl alcohol, phospholipids, sodium lauryl sulfate, sorbitan esters (sorbitan fatty acid esters), isopropyl myristate, isopropyl palmitate, lanolin and oleyl alcohol. In a preferred embodiment, the penetration enhancer used in the stable topical cream comprising 5-Fluorouracil and Calcipotriol is ceteth-20® (polyoxyl 20 cetostearyl ether).

The emulsifying agent can be selected form the group consisting of hypromellose, sodium lauryl sulfate, sorbitan esters (sorbitan fatty acid esters), carboxymethylcellulose sodium, Polyoxyethylene Sorbitan Fatty Acid, Cetostearyl alcohol and Ceteth-20® (polyoxyl 20 cetostearyl ether). In a preferred embodiment, the emulsifying agent used in the stable topical cream comprising 5-Fluorouracil and Calcipotriol is Cetostearyl alcohol.

The buffering agent can be selected form the group consisting of disodium hydrogen phosphate dihydrate, malic acid, sodium borate, sodium citrate dihydrate, sodium borate and sodium hydroxide. In a preferred embodiment, the buffering agents used in the stable topical cream comprising 5-Fluorouracil and Calcipotriol are disodium hydrogen phosphate dihydrate and sodium hydroxide.

The humectant can be selected form the group consisting of glycerin, polydextrose, propylene glycol, sodium lactate, sorbitol, triacetin, trehalose and xylitol. In a preferred embodiment, the humectant used in the stable topical cream comprising 5-Fluorouracil and Calcipotriol is glycerin.

The solvent can be selected form the group consisting of purified water, alcohols, isopropyl alcohol, polyethylene glycol and propylene glycol. In a preferred embodiment, the solvent used in the stable topical cream comprising 5-Fluorouracil and Calcipotriol is purified water.

In a preferred embodiment, the present invention relates to a stable topical cream comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, and the following pharmaceutically acceptable excipients: cetostearyl alcohol, petrolatum, liquid paraffin, dichlorobenzyl alcohol, dl-a tocopherol, Ceteth-20® (polyoxyl 20 cetostearyl ether), disodium hydrogen phosphate dihydrate, disodium edetate, glycerin, and sodium hydroxide and water.

In another embodiment, the stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, can be prepared by a process that involves mixing the components of the water phase and the wax phase until a cream-like consistency is obtained.

The water phase preparation involves the addition of the active ingredients with the pharmaceutically acceptable excipients that are fairly soluble or completely soluble in water such that a clear solution is obtained. Further, the wax phase preparation involves the addition of the pharmaceutically acceptable excipients that are poorly soluble or insoluble in water. Both the wax phase and the water phase are homogenously mixed with stirring, until a cream-like consistency is achieved for the final composition. The obtained topical composition is filled into suitable packaging container such as aluminum collapsible tubes.

In another embodiment, the present invention provides a process for the preparation of a stable composition; wherein the process comprises the steps of:

Water Phase preparation:
1. Transfer required quantity of purified water in a vessel and heat the purified water between 60-65 °C with continuous stirring.
2. Add buffering agent and penetration enhancer into water.
3. Add Calcipotriol, chelating agent and humectant to form a clear solution.
4. Add 5-Fluorouracil and adjust the pH more than 7.0 using NaOH solution.

Wax Phase preparation:
1. Transfer weighed quantity of emollient, antioxidant, emulsifying agent, preservative and ointment base in a vessel.
2. Heat to 70°C-80°C and stir till melt followed by gradual cooling.

Cream preparation:
1. Transfer the hot wax phase maintained at 55°C-60°C in water phase maintained at 25°C-30°C. Homogenize with stirring maintaining the temperature at 25°C-35°C till cream-like consistency is achieved.
2. Fill the cream into suitable packaging container such as aluminum collapsible tubes.

In a preferred embodiment, the present invention provides a process for the preparation of a stable composition; wherein the process comprises the steps of:

Water Phase preparation:
1. Transfer required quantity of purified water in a vessel and heat the purified water between 60-65 °C with continuous stirring.
2. Add Disodium hydrogen phosphate dihydrate and Ceteth-20® into water.
3. Add Calcipotriol, Edetate Disodium and Glycerin to form a clear solution.
4. Add 5-Fluorouracil and adjust the pH more than 7.0 using NaOH solution.

Wax Phase preparation:
1. Transfer weighed quantity of Liquid Paraffin/Mineral oil, dl-a tocopherol, Cetostearyl alcohol, Dichlorobenzyl alcohol and Petrolatum with stirring.
2. Heat to 70°C-80°C and stir till melt followed by gradual cooling.

Cream preparation:
1. Transfer the hot wax phase maintained at 55°C-60°C in water phase maintained at 25°C-30°C. Homogenize with stirring maintaining the temperature at 25°C-35°C till cream-like consistency is achieved.
2. Fill the cream into suitable packaging container such as aluminum collapsible tubes.

The assay of 5-Fluorouracil and Calcipotriol in the topical cream composition according to the present invention can be carried out by any of the methods known to a person skilled in the art. In a preferred embodiment, the assay can be performed by HPLC method.

Examples

The present invention has been described by way of example only, and it is to be recognized that modifications thereto falling within the scope and spirit of the appended claims, and which would be obvious to a person skilled in the art based upon the disclosure herein, are also considered to be included within the scope of this invention.

Example-1: Stable topical pharmaceutical composition
Sr. No. Ingredient Ingredients (% w/w)
1 API 0.001-20
2 Emulsifying agent 1-15
3 Ointment base 2-35
4 Emollient 0.1-20
5 Preservative 0.025-5
6 Antioxidant 0.001-0.1
7 Penetration enhancer 1-15
8 Chelating agent 0.005-2
9 Humectant 0.5-10
10 Solvent 0.5-10
11 Buffering agent q.s. to adjust pH to 7 - 9

The composition of the Example-1 can be prepared by a process that involves mixing the components of the water phase and the wax phase until a cream-like consistency is obtained. The detailed steps of the manufacturing process are mentioned in the detailed description.

Example-2: Stable topical pharmaceutical compositions
Sr. No. Ingredients Quantity (% w/w)
Formula-1 Formula-2 Formula-3 Formula-4 Formula-5 Formula-6
Wax Phase
1 Cetostearyl alcohol 8.0 8.0 8.0 8.0 8.0 8.0
2 Petrolatum 12.0 12.0 12.0 12.0 12.0 12.0
3 Liquid Paraffin 7.0 7.0 7.0 7.0 7.0 7.0
4 Dichlorobenzyl alcohol 0.1 0.1 0.1 0.1 0.1 0.1
5 dl-a tocopherol 0.002 0.002 0.002 0.002 0.002 0.002
Water Phase
1 5-Fluorouracil 2.5 2.5 2.5 2.5 2.5 2.5
2 Calcipotriol 0.0025 0.0025 0.0025 0.0025 0.0025 0.0025
3 Ceteth-20® 3.0 3.0 3.0 3.0 3.0 3.0
4 Disodium hydrogen phosphate dihydrate 0.1 0.1 0.1 0.1 0.1 0.1
5 Disodium Edetate 0.05 - 0.05 - 0.05 -
6 Glycerin 3.0 3.0 3.0 3.0 3.0 3.0
7 Sodium Hydroxide q.s. to pH 7.2 q.s. to pH 7.2 q.s. to pH 8.2 q.s. to pH 8.2 q.s. to pH 8.5 q.s. to pH 8.5
8 Purified water q.s. to 100 q.s. to 100 q.s. to 100 q.s. to 100 q.s. to 100 q.s. to 100

The composition can be obtained by a manufacturing process comprising the following steps:

Water Phase preparation:
1. Transfer required quantity of purified water in a vessel and heat the purified water between 60-65 °C with continuous stirring.
2. Add disodium hydrogen phosphate dihydrate and ceteth-20® into water.
3. Add calcipotriol, edetate disodium and glycerin to form a clear solution.
4. Add 5-Fluorouracil and adjust the pH more than 7.0 using NaOH solution.

Wax Phase preparation:
1. Transfer weighed quantity of liquid paraffin/mineral oil, dl-a tocopherol, cetostearyl alcohol, dichlorobenzyl alcohol and petrolatum with stirring.
2. Heat to 70°C-80°C and stir till melt followed by gradual cooling.

Cream preparation:
1. Transfer the hot wax phase maintained at 55°C-60°C in water phase maintained at 25°C-30°C. Homogenize with stirring maintaining the temperature at 25°C-35°C till cream-like consistency is achieved.
2. Fill the cream into suitable packaging container such as aluminum collapsible tubes.

Example-3: Stability data for pharmaceutical composition of Formula-1
Test parameters Formula-1 (pH 7.2 with EDTA)
Initial 2°C - 8°C 25°C, 60% RH 40°C, 75% RH
2 Months 3 Months 2 Months 3 Months 1 Month
Description White opaque cream White opaque cream White opaque cream White opaque cream White opaque cream White opaque cream
pH 7.15 7.16 7.15 7.18 7.17 7.13
Assay of 5-Fluorouracil (%) 99.8 100.2 99.9 99.4 99.7 99.3
Assay of Calcipotriol (%) 102.2 101.7 101.9 101.1 99.0 92.7
Related Substances of 5-Fluorouracil (%)
Single maximum unknown 0.017 0.016 0.016 0.016 0.014 0.016
Total impurities 0.025 0.023 0.023 0.028 0.028 0.039
Related Substances of Calcipotriol (%)
Pre calcipotriol (Impurity-B) ND ND ND 0.244 0.103 0.903
Impurity-C ND ND ND ND ND ND
Impurity-D ND ND 0.213 1.734 2.39 8.723
Single maximum unknown ND ND ND ND ND 0.158
Total impurities ND ND 0.213 1.978 2.493 9.784
ND = Not detected

The data shows that the assay of 5-Fluorouracil and Calcipotriol is above 95%, when stored at 25 °C / 60% RH for composition at pH 7.2 with chelating agent (EDTA).

Example-4: Stability data for pharmaceutical composition of Formula-2
Test parameters Formula-2 (pH 7.2 without EDTA)
Initial 2°C - 8°C 25°C, 60% RH 40°C, 75% RH
2 Months 3 Months 2 Months 3 Months 1 Month
Description White opaque cream White opaque cream White opaque cream White opaque cream White opaque cream White opaque cream
pH 7.05 7.06 7.05 7.08 7.03 7.02
Assay of 5-Fluorouracil (%) 100.9 99.4 99.3 99.2 100.2 100.6
Assay of Calcipotriol (%) 99.7 98.3 100.3 97.0 96.9 85.7
Related Substances of 5-Fluorouracil (%)
Single maximum unknown 0.016 0.016 0.015 0.016 0.015 0.018
Total impurities 0.024 0.024 0.022 0.025 0.025 0.038
Related Substances of Calcipotriol (%)
Pre calcipotriol (Impurity-B) ND ND ND ND ND 1.512
Impurity-C ND ND ND ND ND ND
Impurity-D ND 0.311 0.337 2.182 2.773 10.199
Single max. unknown ND ND ND ND ND 0.256
Total impurities ND 0.311 0.337 2.182 2.773 11.967

The results exhibit that the presence of chelating agent (EDTA) in the composition marginally helps in stabilizing Calcipotriol in the composition having pH 7.2.

Example-5: Stability data for pharmaceutical composition of Formula-3
Sr. No. Test parameters Formula-3 (pH 8.2 with EDTA)
Initial 2°C - 8°C 25°C, 60% RH 40°C, 75% RH
2 Months 2 Months 2 Months
1 Description White opaque cream White opaque cream White opaque cream White opaque cream
2 pH 8.25 8.24 8.25 8.24
3 Assay of 5-Fluorouracil (%) 100.9 100.2 98.7 98.8
4 Assay of Calcipotriol (%) 102.0 103.0 100.2 94.6
5 Related Substances of 5-Fluorouracil (%)
5-Hydroxyuracil ND ND ND ND
Single maximum unknown 0.015 0.016 0.016 0.047
Limit of Urea ND ND 0.079 0.353
Total impurities 0.022 0.023 0.110 0.458
6 Related Substances of Calcipotriol (%)
Pre calcipotriol (Impurity-B) ND ND ND ND
Impurity-C ND ND ND ND
Impurity-D ND ND 0.283 2.813
Single maximum unknown ND ND ND ND
Total impurities ND ND 0.283 2.813

The results exhibit the favorable impact of pH 8.2 as compared to pH 7.2 for stabilization of Calcipotriol in the cream composition.

Example-6: Stability data for pharmaceutical composition of Formula-4
Sr. No. Test parameters Formula 4 (pH 8.2 without EDTA)
Initial 2°C - 8°C 25°C, 60% RH 40°C, 75% RH
2 Months 2 Months 2 Months
1 Description White opaque cream White opaque cream White opaque cream White opaque cream
2 pH 8.22 8.23 8.22 8.23
3 Assay of Fluorouracil (%) 101.5 100.3 100.0 99.0
4 Assay of Calcipotriol (%) 98.2 98.3 95.5 92.5
5 Related Substances of Fluorouracil (%)
Single maximum unknown 0.016 0.016 0.019 0.075
Total impurities 0.023 0.023 0.167 0.59
6 Related Substances of Calcipotriol (%)
Pre calcipotriol (Impurity-B) ND ND ND ND
Impurity-C ND ND ND 2.338
Impurity-D ND ND 0.263 1.602
Single maximum unknown ND ND ND ND
Total impurities ND ND 0.263 3.940

The data shows that in absence of chelating agent (EDTA) at pH 8.2, the assay of Calcipotriol slightly decreases at 25°C and 40°C.

Example-7: Stability data for pharmaceutical composition of Formula-5
Sr. No. Test parameters Formula 5 (pH 8.5 with EDTA)
Initial 2°C - 8°C 25°C, 60% RH 40°C, 75% RH
2 Months 2 Months 2 Months
1 Description White opaque cream White opaque cream White opaque cream White opaque cream
2 pH 8.52 8.47 8.49 8.48
3 Assay of Fluorouracil (%) 102.2 101.6 100.9 99.6
4 Assay of Calcipotriol (%) 99.7 99.9 99.5 100.6
5 Related Substances of Fluorouracil (%)
Single maximum unknown 0.016 0.016 0.015 0.023
Total impurities 0.024 0.024 0.178 0.767
6 Related Substances of Calcipotriol (%)
Pre calcipotriol (Impurity-B) ND ND ND ND
Impurity-C ND ND ND ND
Impurity-D ND ND ND 0.739
Single maximum unknown ND ND ND ND
Total impurities ND ND ND 0.739

At pH 8.5 with chelating agent (EDTA), assay of both 5-Fluorouracil and Calcipotriol is stable even at accelerated stability condition (40°C / 75% RH). The impurity profile of both 5-Fluorouracil and Calcipotriol is found to be better as compared to pH 8.2.

Example-8: Stability data for pharmaceutical composition of Formula-6
Sr. No. Test parameters Formula 6 (pH 8.5 without EDTA)
Initial 2°C - 8°C 25°C, 60% RH 40°C, 75% RH
2 Months 2 Months 2 Months
1 Description White opaque cream White opaque cream White opaque cream White opaque cream
2 pH 8.49 8.48 8.47 8.49
3 Assay of Fluorouracil (%) 101.2 102.1 99.8 97.9
4 Assay of Calcipotriol (%) 99.5 100.0 97.6 91.6
5 Related Substances of Fluorouracil (%)
Single maximum unknown 0.017 0.015 0.016 0.072
Total impurities 0.025 0.021 0.196 0.823
6 Related Substances of Calcipotriol (%)
Pre calcipotriol (Impurity-B) ND ND ND ND
Impurity-C ND ND ND 0.168
Impurity-D ND ND ND 0.771
Single maximum unknown ND ND ND ND
Total impurities ND ND ND 0.939

The presence of chelating agent (EDTA) shows positive impact on stabilization of both 5-Fluorouracil and Calcipotriol at pH 8.5.

Example-9: Stability data for pharmaceutical composition of Formula-1-6 (2°C - 8°C for 6 months)
Test parameters 2°C - 8°C for 6 months
Formula 1 Formula 2 Formula 3 Formula 4 Formula 5 Formula 6
Description White opaque cream White opaque cream White opaque cream White opaque cream White opaque cream White opaque cream
pH 7.18 7.06 8.24 8.24 8.47 8.48
Assay of 5-Fluorouracil (%) 99.8 99.6 99.6 100.2 100.8 102.2
Assay of Calcipotriol (%) 102.7 98.7 102.5 100.4 99.8 100.0
Related Substances of 5-Fluorouracil (%)
5-Hydroxyuracil ND ND ND ND ND ND
Single maximum unknown 0.016 0.015 0.017 0.018 0.016 0.016
Total impurities 0.023 0.023 0.025 0.085 0.057 0.083
Related Substances of Calcipotriol (%)
Pre calcipotriol (Impurity-B) ND ND ND ND ND ND
Impurity-C 0.199 ND ND ND ND ND
Impurity-D ND 0.417 ND ND ND ND
Single maximum unknown ND ND ND ND ND ND
Total impurities 0.199 0.417 ND ND ND ND
ND: Not Detected

The data confirms that the individual assay of 5-Fluorouracil and Calcipotriol in all the compositions is above 95% when stored at 2°C - 8°C and total impurity of 5-Fluorouracil and Calcipotriol is in control for 6 months.

Example-10: Stability data for pharmaceutical composition of Formula-1-6 (25°C, 60% RH for 6 months)
Test parameters 25°C, 60% RH for 6 months
Formula 1 Formula 2 Formula 3 Formula 4 Formula 5 Formula 6
Description White opaque cream White opaque cream White opaque cream White opaque cream White opaque cream White opaque cream
pH 7.19 7.08 8.25 8.26 8.45 8.47
Assay of 5-Fluorouracil (%) 99.3 100.3 100.0 99.6 98.8 98.1
Assay of Calcipotriol (%) 96.7 94.8 102.2 93.5 98.5 98.3
Related Substances of 5-Fluorouracil (%)
5-Hydroxyuracil ND ND ND ND ND 0.007
Single maximum unknown 0.017 0.015 0.03 0.059 0.036 0.033
Total impurities 0.04 0.032 0.336 0.424 0.594 0.625
Related Substances of Calcipotriol (%)
Pre calcipotriol (Impurity-B) 0.274 0.234 ND ND ND ND
Impurity-C ND ND ND ND ND ND
Impurity-D 3.511 4.131 0.588 0.672 0.129 0.357
Single maximum unknown ND ND ND ND ND ND
Total impurities 3.785 4.365 0.588 0.672 0.129 0.357
ND: Not Detected

Based on the stability results, the Formula-5 was selected for further studies, as this composition remained stable when stored at 25°C / 60% RH for at least six months. The data shows that individual assay of 5-Fluorouracil and Calcipotriol is above 95%, and the total impurity of 5-Fluorouracil and Calcipotriol is not more than 5% when stored at 25°C / 60% RH for at least six months.

Several experiments were performed by the inventors to assess the impact of pH on stabilization of the cream. The results indicated that the pH 8.2 had a favorable impact on cream stability compared to pH 7.2. Further, the presence of chelating agent (EDTA) in the composition showed positive impact on stabilization of both Fluorouracil and Calcipotriol compared to the compositions without chelating agent (EDTA). Fluorouracil and Calcipotriol cream formulated with or without chelating agent (EDTA) at pH 8.5 has even better stabilization of Calcipotriol as compared to formulation with pH 8.2. Presence of chelating agent (EDTA) helps in stabilization of formulation at this pH. Formulation at pH 8.5 is stable at 25°C and is also having better impurity profile at 40°C as compared to formulation with pH 8.2. The results indicate that the pH from 7 to 9 is useful to stabilize Calcipotriol in the presence of 5-Fluorouracil. Further, the pharmaceutical composition remains stable, when stored at 25 °C / 60% RH for at least three months.

Above data indicates that pH plays crucial role in stabilization of Calcipotriol in the presence of Fluorouracil. The Formula-5 was found to be most stable formulation amongst all the formulations studied.

Based on the above batches, it was observed that both Fluorouracil and Calcipotriol were found to be stable even at 25 °C / 60% RH in terms of content and impurities at pH 8.5 in the presence of chelating agent (EDTA). Therefore, a batch was prepared with higher concentration of both Fluorouracil and Calcipotriol at pH 8.5 in the presence of chelating agent (EDTA).

Example-11: Stable topical pharmaceutical composition comprising higher strength of Fluorouracil and Calcipotriol (pH 8.5 with chelating agent)
Sr. No. Ingredients Quantity (% w/w)
Formula 7
Wax Phase
1 Cetostearyl alcohol 8.0
2 Petrolatum 12.0
3 Liquid Paraffin 7.0
4 Dichlorobenzyl alcohol 0.1
5 dl-a tocopherol 0.002
Water Phase
1 Fluorouracil 5.0
2 Calcipotriol 0.005
3 Ceteth-20 3.0
4 Disodium hydrogen phosphate dihydrate 0.1
5 Disodium Edetate 0.05
6 Glycerin 3.0
7 Sodium Hydroxide q.s. to pH 8.5
8 Purified water q.s. to 100

The composition of the above Example can be prepared by the process as described in the Example-2.

Example-12: Stability results of Formula-7 with higher strength of Fluorouracil and Calcipotriol (pH 8.5 with chelating agent)
Test parameters Formula-5 with higher strength of Fluorouracil and Calcipotriol (pH 8.5 with chelating agent)
Initial 2°C - 8°C 25°C, 60% RH 40°C, 75% RH
2 Months 2 Months 3 Months 2 Months 3 Months
Description White opaque cream White opaque cream White opaque cream White opaque cream White opaque cream White opaque cream
pH 8.41 8.40 8.42 8.43 8.45 8.46
Assay (%)
Fluorouracil 100.2 99.3 99.8 99.8 98.3 97.5
Assay of Calcipotriol (%) 98.8 99.2 97.1 97.3 96.8 85.7
Related Substances of 5-Fluorouracil (%)
5-Hydroxyuracil ND ND ND ND ND ND
Single maximum unknown 0.017 0.016 0.013 0.016 0.041 0.068
Total impurities 0.017 0.022 0.013 0.032 0.093 0.148
Related Substances of Calcipotriol (%)
Pre calcipotriol
(Impurity-B) ND ND ND ND ND ND
Impurity-C ND ND ND ND ND ND
Impurity-D ND ND ND 0.211 0.640 1.372
Single maximum unknown ND ND ND ND ND ND
Total impurities ND ND ND 0.211 0.640 1.372

At pH 8.5 with EDTA, the individual assay of 5-Fluorouracil and Calcipotriol in the higher strength composition is at least 95%, and the total impurity in the said composition is not more than 5%, when stored at 25 °C / 60% RH for at least one month, preferably for at least three months. ,CLAIMS:We claim:

1. A stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof with at least one pharmaceutically acceptable excipient, wherein the pH of the said composition is more than 7.

2. The stable topical pharmaceutical composition according to claim 1, wherein the said composition is a cream, an ointment, or a lotion.

3. The stable topical pharmaceutical composition according to claim 1, wherein the concentration of 5-Fluorouracil is 2.5 to 5 % w/w, and the concentration of Calcipotriol is 0.0025 to 0.0050 % w/w % w/w with respect to the total weight of the composition.

4. The stable topical pharmaceutical composition according to claim 1, wherein the concentration of 5-Fluorouracil is 2.5 % w/w and the concentration of Calcipotriol is 0.0025 % w/w, with respect to the total weight of the composition.

5. The stable topical pharmaceutical composition according to claim 1, wherein the concentration of 5-Fluorouracil is 5 % w/w and the concentration of Calcipotriol is 0.0050 % w/w, with respect to the total weight of the composition.

6. The stable topical pharmaceutical composition according to claim 1, wherein the pH of the said composition is from 7 to 9, and further comprising a chelating agent.

7. The stable topical pharmaceutical composition according to claim 1, wherein the pharmaceutically acceptable excipients include cetostearyl alcohol, petrolatum, liquid paraffin, dichlorobenzyl alcohol, dl-a tocopherol, ceteth-20®, disodium hydrogen phosphate dihydrate, disodium edetate, glycerin, and sodium hydroxide, and purified water.

8. The stable topical pharmaceutical composition according to claim 1, wherein the individual assay of 5-Fluorouracil and Calcipotriol in the said composition is at least 95% when stored at 25°C / 60% RH for at least one month.

9. The stable topical pharmaceutical composition according to claim 1, wherein the total impurity in the said composition is not more than 5% when stored at 25°C / 60% RH for at least one month.

10. A stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, wherein the pH of the said composition is from 7 to 9, and wherein the individual assay of 5-Fluorouracil and Calcipotriol is at least 95%, and the total impurity in the said composition is not more than 5% when stored at 25°C / 60% RH for at least one month.

11. A process for preparation of stable topical pharmaceutical composition comprising 5-Fluorouracil and Calcipotriol or pharmaceutically acceptable salts thereof, wherein the pH of the said composition is more than 7, comprising the following steps:
(a) Preparation of water phase:
(i) Transfer required quantity of purified water in a vessel and heat the purified water between 60-65 °C with continuous stirring.
(ii) Add buffering agent and penetration enhancer into water.
(iii) Add Calcipotriol, chelating agent and humectant to form a clear solution.
(iv) Add 5-Fluorouracil and adjust the pH more than 7.0 using NaOH solution.
(b) Wax Phase preparation:
(i) Transfer weighed quantity of emollient, antioxidant, emulsifying agent, preservative and ointment base with stirring in a vessel.
(ii) Heat to 70°C-80°C and stir till melt followed by gradual cooling.
(c) Cream preparation:
(i) Transfer the hot wax phase maintained at 55°C-60°C in water phase maintained at 25°C-30°C. Homogenize with stirring maintaining the temperature at 25°C-35°C till cream-like consistency is achieved.
(ii) Fill the cream into suitable packaging container such as aluminum collapsible tubes.

12. The stable topical pharmaceutical composition according to claim 1, wherein the said composition can be used for human administration for the treatment of actinic keratosis, precancerous skin lesions and other skin diseases.