Endocrine Abstracts

Objective: A reliable form of androgen substitution therapy in terms of favorable kinetics and tolerance as well as effective restoration of androgenicity is paramount in hypogonadal men. A feasible modality is the intramuscular injection of the long-acting ester testosterone undecanoate (TU).

Design: We report data from 22 patients (15 with primary and 7 with secondary hypogonadism) aged 30 to 65 years (mean 43.8±8 years) who received injections of 1000 mg of TU (4 ml - ampoules) for over 8 years.

Results: The medication was well tolerated and local irritation of the injection site was moderate and did not exceed a duration of 3 days. Serum trough levels of testosterone were generally within the low normal range, indicating sufficient substitution. Individual dosing intervals ranged from 10 to 14 weeks. In accordance, patients reported restoration of sexual functions and convenient changes in mood patterns, e.g. gain of vigor and loss of depressiveness. In contrast to short-acting testosterone esters, sensation of fluctuations in androgen concentrations was rarely reported. If this was the case, it was within the last 2 weeks before the next injection as loss of androgenic psychotropic effects. Hemoglobin concentrations and hematocrit were markedly elevated under treatment but remained within the normal range. Prostate size as assessed by transrectal ultrasound remained below 30 ml in all patients and PSA concentrations did not exceed 2.0 μg/l. Bone density as determined by quantitative computer tomography of the lumbar spine or phalangeal ultrasound generally improved in all patients.

Conclusion: In summary, intramuscular injections of testosterone undecanoate represent a feasible, safe and well tolerated modality of androgen substitution in hypogonadal men.