Testosterone undecanoate (injectable)
Anabolic steroidsAlso known as Nebido, Aveed, Test U
A very long depot given every ten to fourteen weeks rather than weekly.
How it works
An eleven-carbon ester in castor oil. The long chain and the viscous vehicle together slow depot release enough to hold levels for months from a single injection.
In the body
Shape of a single dose, modelled as one compartment with first-order absorption. The peak is normalised to 100% because bioavailability and volume of distribution are not published for most of these compounds.
33.9 days in castor oil; 20.9 days when formulated in tea seed oil. The vehicle matters as much as the ester, so the figure is specific to the preparation.
Doses
1000 mg, with the second dose six weeks after the first and every 10 to 14 weeks thereafter. The label carries a boxed warning for pulmonary oil microembolism, which is why it is given under observation.
Vial sizes
Side effects
- Pulmonary oil microembolism, coughing, chest tightness during or just after injection
- A large injection volume, given slowly and deep intramuscular
- As testosterone generally, but harder to reverse quickly given how long the depot lasts
- Monitor: Haematocrit, androgens raise red cell mass, and the rise is dose-dependent
- Monitor: Blood pressure
- Monitor: Lipids, especially a fall in HDL
- Monitor: Total and free testosterone, LH and FSH
- Monitor: Oestradiol, for the aromatising compounds
Cautions
- Prostate or breast cancer
- Trying to conceive
- Polycythaemia
- Pregnancy
- Any situation where a dose may need withdrawing quickly
Status
Prescription-only and in the United States, dispensed through a restricted programme because of the embolism risk. Banned in sport at all times.
Reference information for personal record-keeping. Not medical advice, and not a recommendation to use any of these compounds.