Concentration of Bimatoprost and Its Acid in the Aqeous Humor in Humans

Abstract

Abstract: : Purpose: To determine the concentration of bimatoprost and its acid in the aqeous humor in humans after administration of a single drop. Methods: In a double masked randomized clinical trial 18 subjects scheduled for routine cataract surgery received a single drop of bimatoprost (n=9) or latanoprost (n=9) 2 hours prior to surgery. None of the patients used any other eye drops or had any ocular abnormality other than cataract. Aqueous humor samples were drawn and deep frozen to –70°C. The samples were examined by an independent lab using HPLC–tandem mass spectrometry. The lower limit of quantification was 0.5ng/ml for bimatoprost and 1.0ng/ml for latanoprost. Results: 2 hours after application of a single drop bimatoprost the bimatoprost concentration was (mean±std) 5.3±3.4ng/ml (range 1.9 to 13.7 ng/ml) and concentration of bimatoprost acid was 12.8±5.5ng/ml (range 5.18 to 25.5 ng/ml). After latanoprost administration no latanoprost was detectable in any of the samples. The concentration of latanoprost acid was 22.2±16.3 ng/ml (range 8.0 to 58.1ng/ml) 2 hours after latanoprost administration. Conclusions: In contrast to latanoprost bimatoprost was detectable in the aqeous humor samples and the concentration of bimatoprost acid was significantly lower compared to latanoprost acid. These results suggest that the IOP lowering effect of bimatoprost is caused by different mechanisms compared to latanoprost.

Keywords: drug toxicity/drug effects • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled