ABSORPTION OF TOPICALLY APPLIED HYDROCORTISONE FROM THE EYE OFTHE RHESUS MONKEY

Abstract

Blood samples were collected from anesthetized monkeys during 1 h after topical application of an eyedrop of hydrocortisone acetate suspension, after topical application of a drop of the vehicle alone, and after no application at all. Radioimmunoassay (RIA) showed a rapid and similar increase of hydrocortisone plasma levels in all 3 kinds of experiments. RIA revealed that in monkeys the anesthetic procedure alone was sufficient to cause a considerable increase of endogenous hydrocortisone levels overshadowing any systemic absorption of topical hydrocortisone. Using 3H-hydrocortisone instead a rapid increase of systemic absorption after topical application was found. A plasma concentration of 1% of the dose was found 1 min after topical instillation increasing to a maximum of 6-7% at 30 min. The half time of the slow phase of elimination was .apprx. 19 h.