Flunisolide

Flunisolide is an anti-inflammatory steroid. Flunisolide has demonstrated potent glucocorticoid and weak mineralocorticoid activity in classical animal test systems. As a glucocorticoid, it is several hundred times more potent than the cortisol standard. Clinical studies with flunisolide have shown therapeutic activity on nasal mucous membranes with minimal evidence of systemic activity at the recommended doses.

The mechanisms responsible for the anti-inflammatory action of corticosteroids and for the activity of the aerosolized drug on the nasal mucosa are unknown.

A study in approximately 100 patients that compared the recommended dose of flunisolide nasal solution with an oral dose providing equivalent systemic amounts of flunisolide has shown that the clinical effectiveness of flunisolide nasal solution, when used topically as recommended, is due to its direct local effect and not to an indirect effect through systemic absorption.

Following administration of flunisolide to man, approximately half of the administered dose is recovered in the urine and half in the stool: 65 to 70% of the dose recovered in urine is the primary metabolite, which has undergone loss of the 6α fluorine and addition of a 6β hydroxy group. Flunisolide is well absorbed but is rapidly converted by the liver to the much less active primary metabolite and to glucuronate and/or sulfate conjugates. Because of first-pass liver metabolism, only 20% of the flunisolide reaches the systemic circulation when it is given orally whereas 50% of the flunisolide administered intranasally reaches the systemic circulation unmetabolized. The plasma half-life of flunisolide is 1 to 2 hours.