Initial trial of slow-release testosterone microspheres in hypogonadal men.

The duration of hormone release from testosterone-loaded poly(DL-lactide-co-glycolide) microspheres was assessed in eight hypogonadal men. Eight weeks before receiving testosterone (T) microspheres, patients were withdrawn from their prior androgen therapy in order to minimize the contribution of that therapy to hormone levels measured following microsphere injection. Blood was obtained for hormone measurements immediately before and weekly for 14 weeks after the administration of the T microspheres. A biphasic release of hormone was observed; a significant increase in total T and free T concentration (compared to preinjection values) was observed during week 1 (P less than 0.01) and between weeks 6 and 11 after injection (P less than 0.05). A similar pattern was detected in estradiol and dihydrotestosterone concentrations, whereas T-binding globulin levels showed a small, reciprocal fall after the injection of microspheres (P = not significant [NS]). After receiving the T microspheres, seven of eight hypogonadal men reported the return of normal sexual function; the eight patient withdrew from the study after 5 weeks. It was concluded that T microspheres are a promising new method of androgen replacement therapy for hypogonadal men.