Clobex Mechanism of Action

Pharmacology: Like other topical corticosteroids, CLOBEX (clobetasol propionate) Shampoo, 0.05%, 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.
Pharmacodynamics: Clinical Studies: The safety and efficacy of CLOBEX (clobetasol propionate) Shampoo, 0.05%, has been evaluated in two clinical trials involving 290 adult patients with moderate to severe scalp psoriasis. In both trials, patients were treated with either CLOBEX Shampoo or the corresponding vehicle applied once daily for 15 minutes before lathering and rinsing for a period of 4 weeks. Efficacy results are presented in the table as follows. (See Table 1.)

Click on icon to see table/diagram/image

Clinical studies of Clobetasol Propionate Shampoo, 0.05%, did not include sufficient numbers of non-Caucasian patients to determine whether they respond differently than Caucasian patients with regards to efficacy and safety.
Pharmacokinetics: The extent of percutaneous absorption of topical corticosteroids is determined by many factors, including the vehicle, the integrity of the epidermal barrier and occlusion. Topical corticosteroids can be absorbed from normal intact skin, while inflammation and/or other disease processes in the skin may increase percutaneous absorption.
Due to the fact that circulating levels of corticosteroids are usually below the limit of detection following application, there are no human data regarding the pharmacokinetics of topical corticosteroids. In such cases pharmacodynamic end points, including both hypothalamic-pituitary-adrenal (HPA) axis testing and topical vasoconstriction, are used as surrogates in the assessments of systemic exposure and relative potency, respectively.
In studies evaluating the potential for hypothalamic-pituitary-adrenal (HPA) axis suppression, use of CLOBEX (clobetasol propionate) Shampoo, 0.05%, resulted in demonstrable HPA axis suppression in 5 out of 12 (42%) adolescent patients (see PRECAUTIONS).
CLOBEX Shampoo is in the high range of potency in vasoconstrictor studies.