Pharmacokinetics and Pharmacodynamics of Steroid Esters in Oil Vehicle:
Effects of Ester, Injection Site, and Injection Volume
Variations in side-chain ester chemistry are important in the pharmacokinetics of androgen esters in oil vehicle. In humans, the very short propionate (three-carbon aliphatic) ester of testosterone has distinctly shorter duration of action than esters with longer (seven- or eight-carbon) side-chains. More subtle changes in side-chain ester structure have proven ineffective in altering human clinical pharmacokinetics, because substitution of a linear aliphatic side-chain of seven carbons (enanthate) with either a saturated, cyclized, seven-carbon aliphatic chain (cyclohexanecarboxylate) or a linear, aliphatic, eight-carbon chain (cypionate) resulted in virtually unchanged kinetics. (2, 4-6, 12, 15)
