Disposition and chemical stability of telmisartan 1-O-acylglucuronide.

Telmisartan 1-O-acylglucuronide, the principal metabolite of telmisartan in humans, was characterized in terms of chemical stability and the structure of its isomerization products was elucidated. In addition, pharmacokinetics of telmisartan 1-O-acylglucuronide were assessed in rats after i.v.

Meloxicam: metabolic profile and biotransformation products in the rat.

1. The metabolic fate of 14C-labelled meloxicam was investigated in the urine and bile of rat following oral and intraduodenal administration. Structural elucidation of metabolites was performed by nuclear magnetic resonance, mass spectrometry (electron impact and fast atom bombardment).

Epimerization of erythromycin derivatives.

Dirithromycin (3) isomerizes upon dissolution in different solvents. From X-ray analysis of V-T 108, an analogue of dirithromycin, and comparative 1H and 13C NMR, and MS data, the isomer of dirithromycin was confirmed to be the C-16-(S)-epimer. The ratio of the two epimers at equilibrium conditions was approximately 8:2 (R/S) in methanol at room temperature.

Quaternary N-glucuronides of 10-hydroxylated amitriptyline metabolites in human urine.

1. Conjugated metabolites were isolated from the urine of patients receiving amitriptyline treatment using a combination of solid-phase extraction, h.p.

Glucuronides of hydroxylated metabolites of amitriptyline and nortriptyline isolated from rat bile.

Polar conjugates were isolated from the bile of rats given amitriptyline (AT, unlabeled or labeled with 14C), nortriptyline (NT), or 10-hydroxy (10-OH) derivatives of the drugs. The procedure involved extraction on a column of polystyrene resin, elution with methanol, and separation by preparative TLC followed by reversed phase HPLC. Individual metabolites were characterized by NMR spectroscopy and fast atom bombardment mass spectrometry and by enzymatic or acid deconjugation with subsequent identification of aglycones and glucuronic acid.