Introduction: Testosterone (T) and nandrolone (N) esters in an oil vehicle require deep intramuscular (im) injections by skilled medical personnel. As im injections often deposit injectate into subdermal fat, more convenient self-administered subcutaneous (sc) injections may be feasible.
Aim: To investigate the (a) PK/PD of sc injection of ND in healthy volunteer men using DBS for remote time intensive blood sampling without frequent clinic visits and (b) feasibility of sc injections of androgen ester in an oil vehicle.
Methods: Healthy young eugonadal men (n=8) were administered 100 mg ND in 2 mL arachis oil vehicle by sc injection at a single abdominal site. Capillary blood by finger prick was dried onto filter paper, recording the time of sampling, before and daily for 21 days. Venous blood was sampled before and weekly to store serum and spot onto filter paper. After storage at room temperature, DBS underwent elution and extraction for assay of N and T by LC-MS . Serum N and T concentrations were adjusted for capillary blood sample volume and hematocrit to define peak (N) or nadir (T) time and concentration.
Results: Serum N rose to a peak of 2.50 ± 0.25 (SEM) ng/mL at a median (range) of 6 (4-13) days causing a reduction in serum T representing 89 ± 3% maximal suppression from baseline to a nadir of 0.38 ± 0.13 ng/mL at a median of 8 (5-16 days). Simultaneously sampled capillary and venous blood showed a high correlation for serum N and T
Conclusions: This demonstrates that (a) DBS sampling coupled with LC-MS steroid assays can achieve intensive time sampling for PK/PD studies in the community without requiring frequent clinic visits, venesection or frozen serum storage and (b) androgen esters in an oil vehicle can be delivered predictably and conveniently by sc injection