Pharmacokinetics of intranasal corticosteroids

Topical administration of corticosteroids can reduce the total dose of cort icosteroid required to treat the patient and minimize side effects. This lo gic has led to the development of intranasal corticosteroids (INCS) for all ergic and perennial rhinitis. The second generation of these compounds incl udes beclomethasone dipropionate, budesonide, flunisolide, fluticasone prop ionate, mometasone furoate, and triamcinolone acetonide. There is evidence that the INCS are effective in rhinitis; however, there is concern about th e potential for these compounds to cause growth suppression. In one study, beclomethasone dipropionate significantly reduced growth in children; howev er, treatment of children with mometasone furoate nasal spray for 1 year sh owed no signs of growth th suppression. It is evident that the differences among INCS lie in their pharmacokinetics. Structural differences among the various INCS influence their metabolism. The goal of INCS therapy is to hav e a high ratio of topical to systemic activity. The drug delivery device, a bsorption of the drug, and drug distribution all contribute to effective to pical activity of an INCS. In addition, individual drug metabolism and elim ination (half-life and drug clearance) also contribute to the therapeutic i ndex of a drug. Overall, the second-generation INCS cause minimal systemic effects at recommended doses.