Doping in sport--1. Excretion of 19-norandrosterone by healthy women, including those using contraceptives containing norethisterone.

19-Norandrosterone (19-NA) is the principal urinary metabolite of the anabolic steroid nandrolone and its prohormones. The administration of these 19-nor androgens is prohibited in sport by the World Anti-Doping Agency (WADA) but, even so, adverse findings for 19-NA continue to be commonly reported. Little is known about the urinary concentrations of 19-NA that can occur in women who are not using anabolic steroids, including those using oral contraceptives containing the 19-nor progestogen norethisterone. In 2004, WADA lowered the reporting threshold for 19-NA for females from 5 to 2ng/mL. The lack of any substantial data on 19-NA excretion in women prompted this large-scale investigation. In this investigation, single untimed urines collected from 1202 female volunteers, 38 of whom were taking norethisterone containing contraceptives, were analysed for 19-NA. None of the women was a competitive athlete and pregnancy had been excluded by a urinary test for human chorionic gonadotropin (hCG). Only one sample exceeded the 19-NA reporting threshold having a concentration of 4.1ng/mL. This sample was from a user of a norethisterone-containing contraceptive.

Doping in sport--2. Quantification of the impurity 19-norandrostenedione in pharmaceutical preparations of norethisterone.

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+/-0.01microg (mean+/-S.E.M.) per tablet in those containing 5mg of norethisterone or norethisterone acetate (0.02%, w/w) and up to 0.5+/-0.01microg (mean+/-S.E.M.) per tablet (0.05%, w/w) in oral contraceptive tablets containing 0.35-1.5mg of norethisterone or norethisterone acetate. No tablet tested exceeded the British Pharmacopoeia limit of 0.1% for this impurity.

Doping in sport: 3. Metabolic conversion of oral norethisterone to urinary 19-norandrosterone.

The detection of 19 norandrosterone (19-NA) in a competitor's urine sample is taken as prima facie evidence of administration of nandrolone or other 19-norsteroid but a potential problem is that administration of norethisterone, a progestogen used for menstrual disorders and for hormonal contraception, also results in the excretion of 19-NA that can exceed the laboratory reporting threshold of 2ng/mL. The contribution of norethisterone to urinary 19-NA with and without 19-norandrostenedione, a known norethisterone tablet impurity, requires evaluation. Preparations containing, either <2ng or 1microg 19-norandrostenedione impurity per 5mg of norethisterone, administered to female volunteers (n=10) in doses comparable to those used for menstrual disorders (5mg three times daily for 10 days), resulted in maximal 19-NA concentrations of 51 and 63ng/mL, respectively. The maximal concentration of 19-NA, 2h post-administration of a single 1microg dose of 19-norandrostenedione, was 2.4ng/mL. These results prove unequivocally that norethisterone is metabolized to 19-NA and that there is only a minor contribution from the impurity 19-norandrostenedione. Administration to women (n=30) of a single contraceptive tablet containing norethisterone (1mg) with one of the highest proportions of the impurity 19-norandrostenedione ( approximately 0.5microg, 0.05%, w/w) resulted in a urinary 19-NA concentration of 9.1ng/mL, with a maximum concentration ratio of 19-NA to the norethisterone metabolite 3alpha,5beta-tetrahydronorethisterone of 0.36. We provide data that should remove the need for time-consuming follow-up investigations to consider whether doping with 19-norandrogens has occurred.