Marketed simply as “Sustanon,” this amber-colored, oil-based injectable is famous for one thing: it contains four different testosterone esters in a single 1 mL ampoule. But what exactly is inside that 250 mg blend, how do the esters differ, and why did Aspen engineer it this way? Below you’ll find the most comprehensive, science-backed breakdown available online—perfect for patients, athletes, and curious clinicians alike.
Sustanon 250 is a prescription-only, injectable testosterone preparation manufactured by Aspen Pharma. Each box contains 1 mL glass ampoules (or vials in some markets) of a clear, pale-yellow oil solution. Although it’s FDA-unapproved in the United States, Sustanon is widely prescribed in Europe, the U.K., Australia, South Africa, and New Zealand for:
The “250” simply denotes 250 mg of total testosterone esters per milliliter—but not 250 mg of pure testosterone. Because each ester adds molecular weight, you actually get ≈ 176 mg of raw testosterone per milliliter once the ester groups are cleaved off in vivo .
*Half-lives in oil-based intramuscular depot; individual variation ± 20 %.
Total: 250 mg esterified testosterone → ≈ 176 mg free testosterone .
Single-ester products (e.g., testosterone enanthate or cypionate) create a peaked, wave-like pharmacokinetic curve. Sustanon’s multi-ester design aims for:
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