BETAMETHASONE � betamethasone dipropionate cream
Global Pharmaceuticals, Division of Impax Laboratories Inc.
Rx only
(Potency expressed as betamethasone)
*Vehicle augments the penetration of the steroid.
For Dermatologic Use Only � Not for Ophthalmic Use
DESCRIPTION
Betamethasone Dipropionate Cream, USP 0.05% (Augmented) contains betamethasone dipropionate, USP, a synthetic adrenocorticosteroid, for dermatologic use in an emollient base. Betamethasone, an analog of prednisolone, has a high degree of corticosteroid activity and a slight degree of mineralocorticoid activity. Betamethasone dipropionate is the 17, 21-dipropionate ester of betamethasone.
Chemically, betamethasone dipropionate is 9-fluoro-11?,17,21-trihydroxy-16?-methylpregna-1,4-diene-3,20-dione 17,21-dipropionate, with the empirical formula C28 H37 FO7 , a molecular weight of 504.6, and the following structural formula:
165d0921-figure-01
(click image for full-size original)
Betamethasone dipropionate is a white to creamy white, odorless crystalline powder, insoluble in water.
Each gram of Betamethasone Dipropionate Cream, USP 0.05% (Augmented) contains: 0.643 mg betamethasone dipropionate, USP (equivalent to 0.5 mg betamethasone) in an emollient cream base of purified water, USP; chlorocresol, NF; propylene glycol, USP; white petrolatum, USP; white wax, NF; cyclomethicone; sorbitol solution, USP; glyceryl oleate/propylene glycol; ceteareth-30; carbomer 980, NF; and sodium hydroxide.
CLINICAL PHARMACOLOGY
The corticosteroids are a class of compounds comprising steroid hormones secreted by the adrenal cortex and their synthetic analogs. In pharmacologic doses, corticosteroids are used primarily for their anti-inflammatory and/or immunosuppressive effects.
Topical corticosteroids, such as betamethasone dipropionate, are effective in the treatment of corticosteroid-responsive dermatoses primarily because of their anti-inflammatory, antipruritic, and vasoconstrictive actions. However, while the physiologic, pharmacologic, and clinical effects of the corticosteroids are well known, the exact mechanisms of their actions in each disease are uncertain. Betamethasone dipropionate, a corticosteroid, has been shown to have topical (dermatologic) and systemic pharmacologic and metabolic effects characteristic of this class of drugs.
Pharmacokinetics
The extent of percutaneous absorption of topical corticosteroids is determined by many factors including the vehicle, the integrity of the epidermal barrier, and the use of occlusive dressings. (See DOSAGE AND ADMINISTRATION section.)
Topical corticosteroids can be absorbed through normal intact skin. Inflammation and/or other disease processes in the skin may increase percutaneous absorption. Occlusive dressings substantially increase the percutaneous absorption of topical corticosteroids. (See DOSAGE AND ADMINISTRATION section.)
Once absorbed through the skin, topical corticosteroids enter pharmacokinetic pathways similar to systemically administered corticosteroids. Corticosteroids are bound to plasma proteins in varying degrees, are metabolized primarily in the liver and excreted by the kidneys. Some of the topical corticosteroids and their metabolites are also excreted into the bile.
Betamethasone Dipropionate Cream, USP 0.05% (Augmented) was applied once daily at 7 grams per day for 1 week to diseased skin, in adult patients with psoriasis or atopic dermatitis, to study its effects on the hypothalamic-pituitary-adrenal (HPA) axis. The results suggested that the drug caused a slight lowering of adrenal corticosteroid secretion, although in no case did plasma cortisol levels go below the lower limit of the normal range.