The Metabolism of Methazolamide - Identification of Metabolites in Guinea Pig Urine

Kenichi      Kishida; Norihiro      Yamamura; Yoshiaki      Iwai; Yoshiteru      Sakamoto; Makihiko      Kuhara; Tetsuo      Sasabe

Abstract

The in vivo metabolism of methazolamide, a carbonic anhydrase inhibitor, was studied using guinea pigs as the animals. 14C-Labeled methazolamide was synthesized. Eighty percent of intraperitoneally injected radioactivity was recovered from urine and feces within 24 hours. HPLC analysis on a C18 column detected 2 radioactive metabolites (Peaks A and B). The Peaks A and B were isolated from the urine of the animals dosed with non-radioactive methazolamide. They were purified on the C18 column. Their chemical structure was revealed by UV-absorbance spectra and LC/MS, and confirmed by comparing it with that of chemically synthesized compound. They were a glucuronide, (2-acetylimino-3- methyl-Δ4-1,3,4-thiadiazol-5-yl)-1-thio-β-D-glucopyranosiduronic acid, and a sulfonic acid, N-[3-methyl-5-sulfo-1,3,4- thiadiazol-2(3H)-ylidene]acetamide.

Keywords: Glucuronide, guinea pig, LC/MS, methazolamide, metabolism, sulfonic acid, carbonic anhydrase inhibitor, HPLC analysis, radioactive metabolites, UV-absorbance spectra, thio-D-glucopyranosiduronic acid, acetamide, dorzolamide, ocular hypotensive agents, in-traocular surgery, sulfonamides, Acetazolamide, epilepsy, thiazides, loop diuretics, metabolic acidosis, acidotic coma, sulfona-mides, Ste-vens-Johnson syndrome, toxic epidermal necro-lysis (TEN), immunogenetic, glutathione conjugation, cysteine conjugate, N-acetyltransferase, nephrotoxicity, drug-metabolizing enzyme, acetonitrile, perchloric acid, Iodomethane, Glucuronidase, Phosphate-buffered saline, pentobarbital, radiochromatogram, UV absorbance chromatogram, ascorbic acid, radioactivity, glacial acetic acid, rotary evaporator, lyophilization, Collision-induced dissociation (CID), helium gas, mass spectrum data, wavelength scanning, tri-O-acetyl-D-glucopyranosyl bromide, uronate, chloroform, chlorine gas, Electron ionization, mass spectrometry, re-crystallization, FAB-mass spectrometry, EI-mass spectrome-try, methoxybenzylation, Electrospray mass analysis, collision energy, methanesulfonic acid, mercapturic acid, thioether, monooxygenase