Like other topical corticosteroids, halobetasol propionate has anti-inflammatory, antipruritic and vasoconstrictive actions. The mechanism of the anti- inflammatory activity of the topical corticosteroids, in general, is unclear However, corticosteroids are thought to act by the induction of phospholipase A 2 inhibitory proteins , collectively called lipocorins 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 A 2 .
Patients requiring oral corticosteroids should be weaned slowly from systemic corticosteroid use after transferring to ADVAIR HFA. Prednisone reduction can be accomplished by reducing the daily prednisone dose by mg on a weekly basis during therapy with ADVAIR HFA. Lung function (mean forced expiratory volume in 1 second [FEV 1 ] or morning peak expiratory flow [AM PEF]), beta-agonist use, and asthma symptoms should be carefully monitored during withdrawal of oral corticosteroids. In addition, patients should be observed for signs and symptoms of adrenal insufficiency, such as fatigue, lassitude, weakness, nausea and vomiting, and hypotension.