Clobetasol

METHOD OF PREPARATION

1. Calculate the required quantity of each ingredient for the total amount to be prepared.

2. Accurately weigh and/or measure each ingredient.

4. Add the clobetasol propionate and sodium lauryl sulfate to the isopropyl myristate and mix well.

5. Add sufficient alcohol to volume and mix well.

6. Package in a spray bottle and label.

PACKAGING

Package in tight, light-resistant containers.1

LABELING

Keep out of reach of children. Use only as directed.

STABILITY

A beyond-use date of up to 6 months is appropriate for this preparation.1

USE

Clobetasol Topical Spray is used as an anti-inflammatory agent for topical application.

QUALITY CONTROL

Quality-control assessment can include weight/volume, specific gravity, active drug assay, color, rheological properties/pourability, physical observation and physical stability (discoloration, foreign materials, gas formation, mold growth).2

DISCUSSION

A wide variety of topical anti-inflammatory agents are available, but relatively few are in topical-spray dosage forms. Clobetasol propionate is used in a wide range of disorders. The topical spray is water-miscible and can be easily removed with warm water from the affected area.

Clobetasol propionate (C^sub 25^H^sub 32^ClFO^sub 5^, MW 466.97) occurs as a white to cream-colored crystalline powder. It is practically insoluble in water, slightly soluble in diethyl ether, sparingly soluble in ethanol and soluble in acetone and dimethyl sulfoxide. It should be stored in a tight, light-resistant container. Clobetasol Propionate Topical Solution USP is preserved in tight containers and at controlled room temperature; it is not to be refrigerated. Clobetasol propionate is a synthetic fluorinated corticosteroid classified as an anti-inflammatory agent used in the relief of inflammation of moderate to severe corticosteroid-responsive dermatoses. It appears to stimulate the synthesis of enzymes needed to decrease inflammation, suppress mitotic activity and cause vasoconstriction.1

Sodium lauryl sulfate (C^sub 12^H^sub 25^NaO^sub 4^S, MW 288.38, dodecyl sodium sulfate, SLS) is a mixture of sodium alkyl sulfates consisting chiefly of sodium lauryl sulfate. It is widely used as an anionic surfactant, detergent, emulsifying agent, skin penetrant, tablet and capsule lubricant and wetting agent. It occurs as white- or cream- to pale yellow-colored crystals, flakes or powder with a smooth feel and a soapy, bitter taste and a taint odor ot tatty substances. It is freely soluble in water, giving an opalescent solution, and it is practically insoluble in chloroform and ether. A 1% w/v aqueous solution has a pH in the range of 7.0 to 9.5.1

Isopropyl myristate (C^sub 17^H^sub 34^O^sub 2^, MW 270.51) is composed of esters of propan-2-ol and saturated high molecular weight fatty acids, principally myristic acid. It is used as an emollient, solvent, skin penetrant and oleaginous vehicle. It is absorbed readily by the skin and is used as a component of semisolid bases in pharmaceutical and cosmetic formulations. It is used as a detergent (0.002% to 0.02%), in perfumes (0.5% to 2.0%), soap (0.03% to 0.3%), topical aerosols (2% to 98%) and in topical creams and lotions (1% to 10%). It is a clear, colorless, practically odorless, mobile liquid with a bland taste. It has a specific gravity of 0.846 to 0.854, a boiling point of 140.2°C and a freezing point of about 3°C. It is miscible with acetone, chloroform, ethanol, ethyl acetate, fats, fatty alcohols, fixed oils, liquid hydrocarbons and waxes; it is practically insoluble in glycerin, propylene glycol and water. It is resistant to oxidation and hydrolysis and does not become rancid, but should be stored in a well-closed container in a cool, dry place protected from light.4

Alcohol (C^sub 2^H^sub 5^OH, MW 46.07, ethyl alcohol, ethanol, grain alcohol) is a clear, colorless mobile and volatile liquid with a slight, characteristic odor and a burning taste. Alcohol USP refers to 95% ethanol and dehydrated alcohol refers to 99.5% alcohol. Its specific gravity is between 0.812 to 0.816, and its boiling point is 78.15°C. It is miscible with chloroform, glycerin and water.5

REFERENCES

1. US Pharmacopeial Convention, Inc. United States Pharmacopeia 27-National Formulary22. Rockville, MD: US Pharmacopeial Convention, Inc.; 2004: 2345-2349, 2756.

2. Allen LV Jr. Standard operating procedure for performing physical quality assessment of oral and topical liquids. IJPC1999; 3(2): 146-147.

3. Behn S. Sodium lauryl sulfate. In: Kibbe AH, ed. Handbook of Pharmaceutical Excipients. 3rd ed. Washington, DC: American Pharmaceutical Association; 2000: 487-489.

4. Taylor AK. Isopropyl myristate. In: Kibbe AH, ed. Handbook of Pharmaceutical Excipients. 3rd ed. Washington, DC: American Pharmaceutical Association; 2000: 265-266.

5. Owen SC. Alcohol. In: Rowe RC, Sheskey PJ, Weller PJ, eds. Handbook of Pharmaceutical Excipients. 4th ed. Washington, DC: American Pharmaceutical Association; 2003:13-15.

Copyright International Journal of Pharmaceutical Compounding Mar/Apr 2005
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