Product name: Sustanon

Chemical Structure: 17b-hydroxy-4-androsten-3-one

Sustanon 250 is a trade name for an oil-based injectable blend of four esterized testosterone compounds:

30 mg testosterone propionate
60 mg testosterone phenylpropionate
60 mg testosterone isocaproate
100 mg testosterone decanoate
Sustanon 100 was similar, though with three esters. This smaller dose was usually for pediatric use.

20 mg testosterone propionate
40 mg testosterone phenylpropionate
40 mg testosterone isocaproate
Sustanon 100 has not been produced since 2009.

The different testosterone esters provide for different half lives. Esterization of the testosterone molecules provides for a sustained (but non-linear) release of testosterone from the injection depot into the blood plasma.

While the intention of the mixed testosterone esters in Sustanon is to provide more stable serum testosterone levels, a single long-ester testosterone, such as testosterone cypionate or testosterone enanthate, may actually provide more stable serum testosterone levels. It is the preferred method of testosterone replacement in the UK as detailed in the British National Formulary.