14C-erythromycin

C]Phenacetin and [N-Methyl-14C]Erythromycin as marker substrates for CYP2E1, CYP2D6, CYP1A2 and CYP3A4, respectively with a 14C-CH20 or 14C-C2H4O read out after a simple and rapid extraction method. 

Rae JM, Soukhova NV, Flockhart DA, Desta Z (2002) Tri-ethylenethiophosphoramide is a specific inhibitor of cytochrome P450 2B6 implications for cyclophosphamide metabolism. Drug Metab Dispos 30(5) 525-530 Riley R, Howbrook D (1997) In vitro analysis of the activity of the major human hepatic CYP enzyme (CYP3A4) using [N-methyl-14C]-erythromycin. J Pharmacol Toxicol Methods 38(4) 189-193... 

The most used and validated probe drugs for C YP3 A phenotyping are midazolam and 14C-erythromycin (Watkins 1994). Alfentanyl, alprazolam, dapsone, dextromethorphan, lidocaine. nifedipine, omeprazole, quinine, verapamil have also been used but less frequently, and CYP3A specificity for some of them has been questioned. The endogenous 6(->-hydroxycortisol test (measurement of 6 3-hydroxycortisol cortisol ratio in urine) is only useful for detecting CYP3A induction, and may be influenced by renal CYP3 A activity. 

C- erythromycin breath test or ERMBT CYP3A4 catalyzes the N-desmethylation of [14C N-methyl] erythromycin. The test consists in the measurement of a single breath expired 14C02 collection obtained at 20 minutes following the iv administration of a 0.03 mg... 

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