Determination of MK-507, a novel topically effective carbonic anhydrase inhibitor, and its de-ethylated metabolite in human whole blood, plasma, and urine by high-performance liquid chromatography.
Sensitive methods for the determination of a novel topically effective carbonic anhydrase inhibitor (CAI) I, MK-507, and its de-ethylated metabolite II, in human whole blood, plasma and urine were developed. These methods were based on liquid-liquid extraction of I and II from biological matrices, back extraction into acid, and analysis by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection (252 nm). The assays were fully validated in the concentration range of 5 to 500 ng/ml, and the limit of quantification (LOQ) for I and II, defined as the lowest concentration on the standard curve for which precision (coefficient of variation, C.V.) is < 10%, was 5 ng/ml in whole blood, plasma, and urine. These methods were applied for the analyses of biological fluid samples from a variety of clinical pharmacokinetic studies. In addition, a method in whole blood based on column-switching HPLC with UV detection and with an LOQ of 50 ng/ml was also developed. The switching valve was used to eliminate interferences from late eluting peaks extracted from whole blood. The details of these assays, together with some representative data from a human study, are presented.
Merck Research Laboratories, West Point, PA 19486.
B K
BK
Matuszewski
M L
ML
Constanzer
E J
EJ
Woolf
T
T
Au
H
H
Haddix
D002257:Carbonic Anhydrase Inhibitors / Q000008:administration & dosage / Q000032:analysis* / Q000493:pharmacokinetics; D002851:Chromatography, High Pressure Liquid; D003640:Dealkylation; D006801:Humans; D007202:Indicators and Reagents; D009883:Ophthalmic Solutions; D012015:Reference Standards; D013056:Spectrophotometry, Ultraviolet; D013449:Sulfonamides / Q000008:administration & dosage / Q000032:analysis* / Q000493:pharmacokinetics; D013876:Thiophenes / Q000008:administration & dosage / Q000032:analysis* / Q000493:pharmacokinetics
D002257:Carbonic Anhydrase Inhibitors; D007202:Indicators and Reagents; D009883:Ophthalmic Solutions; D013449:Sulfonamides; D013876:Thiophenes; C062765:dorzolamide