Doping in sport—2. Quantification of the impurity 19-norandrostenedione in pharmaceutical preparations of norethisterone
摘要:
The finding of measurable amounts of 19-norandrostenedione in norethisterone tablets prompted us to develop an assay to quantify this steroid. 19-Norandrostenedione is an anabolic steroid whose use in sport is prohibited by the World Anti-Doping Agency (WADA). The assay was developed using isotope dilution and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the quantification of 19-norandrostenedione in norethisterone formulations, with [3,4(-13)C(2)]-19-norandrostenedione as the internal standard. The results showed amounts up to 1.01 +/- 0.01 mu g (mean +/- S.E.M.) per tablet in those containing S mg of norethisterone or norethisterone acetate (0.02%, w/w) and up to 0.5 +/- 0.01 mu g (mean S.E.M.) per tablet (0.05%, w/w) in oral contraceptive tablets containing 0.35-1.5 mg of norethisterone or norethisterone acetate. No tablet tested exceeded the British Pharmacopoeia limit of 0.1% for this impurity. (C) 2008 Elsevier Inc. All rights reserved.
A-ring enollactones la, lb, or 9 derived from 4-cholesten-3-one, testosterone benzoate or 3-oxo-4-estren-17 beta-yl benzoate were condensed with [1,2-13C2]acetyl chloride to give intermediates 2a, 2b, or 10. 2a and 2b were cyclized by acid or base to give 3,4 13c-labeled 4-cholesten-3-one and testosterone, respectively. [3,4-13c2 14-Cholesten-3-one was converted via reduction of its trimethylsilyl enol ether to [3,4-13C2] cholesterol. Acetyl enollactone 10 was cyclized in acetic acid to [3,4-13c2] 3-oxo-4-estren-17beta-yl benzoate followed by aromatization and hydrolysis to produce ]3,4-13c2] estradiol-17 beta. Alternatively, cyclization of 10 with base afforded [3,4-13c2-oxo-4-estren-17 beta-ol directly, which was then oxidized and aromatized to yield ]3,4-13c2] estrone. Ozonolysis of progesterone, conversion to the diketal ester 16 and acylation followed by acid hydrolysis furnished [3,4-13c2] progesterone.