2 popular esters of Nandrolone and their effects on plasma concentrations in different muscle groups.
This study compared the pharmacokinetics and pharmacodynamics of two currently available esters of nandrolone, the decanoate and phenylpropionate, as well as the influence of i.m. injection sites (gluteal vs. deltoid) and injection volumes (4 ml vs. 1 ml). In addition to measuring plasma nandrolone to investigate pharmacokinetics, we measured plasma testosterone and inhibin by radioimmunoassay to determine the pharmacodynamic effects of nandrolone-induced inhibition of pituitary gonadotrophin secretion, as reflected in LH-dependent Leydig (testosterone) and FSH-dependent Sertoli (inhibin) cell function in healthy men. We analyzed these data using an indirect pharmacodynamic response model, which has demonstrated, for the first time, prominent pharmacological differences between esters differing in only a single carbon in the side-chain, as well as systematic differences attributable to injection site and volume in humans.
Fig. 1. Time course of plasma nandrolone concentrations in 23 healthy men over 32 days after i.m. injection of 100 mg of nandrolone phenylpropionate in 4 ml of arachis oil vehicle into the gluteal muscle (group 1) () or injection of 100 mg of nandrolone decanoate into the gluteal muscle in 4 ml of arachis oil vehicle (group 2) (), into the gluteal muscle in 1 ml of arachis oil vehicle (group 3) () or into the deltoid muscle in 1 ml of arachis oil vehicle (group 4) (). Results are expressed as mean and S.E.M., unless the S.E. is smaller than symbol.