Test Enanthate 250mg/mL | 10-Vial
C7 ester · ~7 day t½
QSC Peptides
$280Buy →
≥99% Pure · COA
Testosterone esters are formed by esterification of the C17β-hydroxyl group of testosterone with fatty acids of varying carbon chain length. This converts the free hydroxyl to an ester bond, dramatically increasing lipophilicity and enabling slow depot release after intramuscular injection.
After injection, the ester-linked testosterone dissolves slowly from the oil depot into surrounding tissue. Plasma esterases then cleave the ester bond, releasing free testosterone into circulation. Release rate is governed by the ester's lipophilicity (a function of carbon chain length and structure) — longer chains = greater lipophilicity = slower release = longer half-life.
Each additional carbon in the ester chain increases the partition coefficient (log P) by approximately 0.5 units. This produces a predictable relationship between ester chain length and half-life: Propionate (C3, ~2 days) → Phenylpropionate (ring + C3, ~5 days) → Enanthate (C7, ~7 days) → Cypionate (cyclopentyl + C3 ~8 days) → Decanoate (C10, ~15 days) → Undecylenate (C11 + double bond, ~14 days).
| Ester | Chemistry | Half-Life | Free Test % | Cmax Time | QSC Price |
|---|---|---|---|---|---|
| Enanthate | Heptanoate (C7 linear) | ~7 days | ~72% | ~2-3 days | $280 / 10-vial |
| Cypionate | Cyclopentylpropionate (~C8) | ~8 days | ~70% | ~2-4 days | $280 / 10-vial |
| Propionate | Propionate (C3 linear) | ~2 days | ~83% | ~12-24 hrs | $240 / 10-vial |
| Suspension | No ester (aqueous) | <1 day | 100% | ~1-4 hrs | $230 / 10-vial |
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QSC Peptides