Clobetasol (Clobetasol Propionate Topical) - Description and Clinical Pharmacology

Rx only

For External Use Only - Not for Ophthalmic Use.

DESCRIPTION

Clobetasol Propionate Ointment USP contains the active compound clobetasol propionate, a synthetic corticosteroid, for topical dermatologic use. Clobetasol, an analog of prednisolone, has a high degree of glucocorticoid activity and a slight degree of mineralocorticoid activity.

Chemically, clobetasol propionate is (11β, 16β)-21-chloro-9-fluoro-11-hydroxy-16-methyl-17-(1-oxopropoxy)pregna-1,4-diene-3,20-dione, and it has the following structural formula:

Clobetasol propionate has the molecular formula C₂₅H₃₂ClFO₅ and a molecular weight of 467. It is a white to cream-colored crystalline powder insoluble in water.

Each gram of Clobetasol Propionate Ointment USP, 0.05% contains 0.5 mg clobetasol propionate in an ointment base of propylene glycol, sorbitan sesquioleate, and white petrolatum.

CLINICAL PHARMACOLOGY

Like other topical corticosteroids, clobetasol propionate has anti-inflammatory, antipruritic, and vasoconstrictive properties. The mechanism of the anti-inflammatory activity of the topical steroids, in general, is unclear. However, corticosteroids are thought to act by the induction of phospholipase A₂ inhibitory proteins, collectively called lipocortins. It is postulated that these proteins control the biosynthesis of potent mediators of inflammation such as prostaglandins and leukotrienes by inhibiting the release of their common precursor, arachidonic acid. Arachidonic acid is released from membrane phospholipids by phospholipase A₂.

Pharmacokinetics

The extent of percutaneous absorption of topical corticosteroids is determined by many factors, including the vehicle and the integrity of the epidermal barrier. Occlusive dressings with hydrocortisone for up to 24 hours has not been demonstrated to increase penetration; however, occlusion of hydrocortisone for 96 hours markedly enhances penetration. Topical corticosteroids can be absorbed from normal intact skin. Inflammation and/or other disease processes in the skin may increase percutaneous absorption.

Studies performed with clobetasol propionate ointment indicate that it is in the super-high range of potency as compared with other topical corticosteroids.