Article date: October 1984
By: DJ Back, JL Maggs, HS Purba, S Newby, BK Park, in Volume 18, Issue 4, pages 603-607
The metabolism of [3H]ethinyloestradiol (EE2) was investigated in six male subjects who had been phenotyped with respect to sparteine metabolism (three metabolizers and three non‐metabolizers). Urinary metabolite profiles of EE2 were virtually identical. Following enzyme hydrolysis of sulphate and glucuronide conjugates the major urinary metabolite was 2‐methoxyEE2. The ratio EE2:2‐methoxyEE2 was taken as a measure of EE2 2‐hydroxylation (metabolizers, 2.4 +/‐ 0.3; non‐ metabolizers, 2.5 +/‐ 0.4). Primaquine (45 mg), previously shown to inhibit antipyrine metabolism, had no effect on EE2 2‐hydroxylation. Supporting studies in rats showed that acute administration of primaquine (50 mg/kg) and 1‐methylimidazole (50 mg/kg) inhibited antipyrine but not EE2 metabolism. It is concluded that the cytochrome P‐450 enzyme responsible for 2‐hydroxylation of EE2 is distinct from the enzymes involved in the oxidation of sparteine and antipyrine.
DOI: 10.1111/j.1365-2125.1984.tb02511.x
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