Schumann W.
Institut fur Mikrobiologie und experimentelle Therapie
(ZIMET), Jena.
Disposition and excretion of the anabolic steroid Oral-
Turinabol (1;4-chloro-17 alpha-methyl-androsta-1,4-diene-17
beta-hydroxy-3-one) were investigated in male volunteers.
Following single p.o. and i.v. administration of the tritium-
labelled compound the plasma concentration courses of total
radioactivity (1 and 1-metabolites) and of the unchanged
parent drug as well as the urinary excretion were estimated.
From these data model independent pharmacokinetic parameters
based on statistical moments were calculated. 1 is almost
completely absorbed after p.o. administration of 10 mg per
volunteer. Peak concentrations of total radioactivity and of 1
in plasma were reached about 3 h p.a. Irregularities
observed in the plasma level profile following both p.o. and
i.v. administration of 1 are due to a marked enterohepatic
circulation. Orally given 1 is subject to a first-pass
effect, resulting in a diminished systematic availability.
The AUC-ratio of the unchanged drug and the total
radioactivity of 1 : 13 shows the predominance of metabolites
in plasma. After i.v. administration the disposition of
unchanged 1 was found biphasically with a terminal half-life
of 16 h. 1 and its metabolites are preferentially excreted
via the kidneys. The urinary total radioactivity represented
about 60% of the dose following both administrations. Due to
its affinity to SHBG 1 is able to compete for the protein
binding of testosterone, resulting in an increased plasma
level of non protein-bound testosterone.
NO Aromatization (due to the Chloro addition) and it can not alpha-5 reduce to DHT.
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