What is the main mechanism of action (MOA) of topical corticosteroids?

Topical corticosteroids primarily exert their anti-inflammatory effects by inhibiting phospholipase A2, which is a critical enzyme involved in the inflammatory process. When phospholipase A2 is inhibited, there is a reduction in the release of arachidonic acid from membrane phospholipids. Arachidonic acid is a precursor for the synthesis of various inflammatory mediators, including prostaglandins and leukotrienes, which are responsible for the signs and symptoms of inflammation such as redness, swelling, and pain.

By preventing the production of these mediators, corticosteroids help to control inflammation and reduce the associated discomfort. This mechanism is a key reason why topical corticosteroids are effective in treating various inflammatory conditions of the skin and eyes, as they can target localized inflammation without significant systemic effects when used appropriately.