Ocular and Systemic Pharmacokinetics Of Latanoprost in Humans

The ocular pharmacokinetics of latanoprost (13,14-dihydro-17-phenyl-18, 19,20-trinor-PGF 2α-isopropyl ester; Xalatan [Pharmacia-Upjohn, Peapack, NJ]) was studied in patients undergoing cataract surgery using radio-immunoassay, and the systemic pharmacokinetics of latanoprost was studied in healthy human volunteers with 3H-latanoprost as well as radioimmunoassay. After topical application, latanoprost was rapidly hydrolysed in the cornea and blood. The maximum concentration of the active drug, latanoprost acid, was detected in the aqueous humor 1–2 hours after topical administration of the clinical dose and amounted to 15–30 ng/ml. The half-life of latanoprost acid in the aqueous humor was 2–3 hours. In the systemic circulation the peak concentration of latanoprost acid appeared 5 minutes after topical application and reached a level of 53 pg/ml with an elimination half-life of 17 minutes. In patients that had been on the drug continuously for more than 1 year, 5 out of 10 had plasma levels of latanoprost acid below the limit of detection (