The metabolites of nandrolone, a 19-nor anabolic steroid, are primarily formed through hepatic metabolism involving reduction, hydroxylation, and conjugation. Key metabolites include:
1.19-Norandrosterone (19-NA):
Formed via 5α-reduction of the A-ring double bond and oxidation of the 17β-hydroxyl group to a ketone.
This is the primary urinary metabolite detected in doping tests, often as a glucuronide conjugate.
2.19-Noretiocholanolone (19-NE):
The 5β-reduced isomer of 19-norandrosterone, formed through 5β-reduction.
Also excreted as a glucuronide and used alongside 19-NA for anti-doping screening.
3.Minor Hydroxylated Metabolites:
18-Hydroxynandrolone and 16β-Hydroxynandrolone: Result from hydroxylation at the 18 or 16 positions.
6β-Hydroxynandrolone: A less common metabolite formed via 6β-hydroxylation.
4.Conjugated Forms:
Metabolites like 19-NA and 19-NE are conjugated with glucuronic acid (phase II metabolism) to enhance water solubility for urinary excretion.
Detection in Doping Tests:
19-Norandrosterone glucuronide is the gold-standard biomarker for nandrolone use. Elevated levels (>2 ng/mL in urine) trigger further investigation.
The ratio of 19-NA to 19-NE helps distinguish recent administration from prolonged excretion.
Notes:
Nandrolone itself (19-nortestosterone) is not typically detected in urine due to rapid metabolism.
Aromatization to estrogenic compounds (e.g., estradiol) is minimal compared to testosterone.
These metabolites are critical for identifying nandrolone misuse in sports and medical monitoring.
