An exploratory study of the effects of 12 month administration of the novel long-acting testosterone undecanoate on measures of sexual function and the metabolic syndrome.

Administration of testosterone undecanoate (TU) over 12 months to men with sexual dysfunction and signs of the metabolic syndrome, restored their plasma testosterone (T) levels to the mid-range of reference values. This had a beneficial effect on their sexual functioning as evidenced by an improvement of their scores on the International Index of Erectile Function. The scores on the Aging Male Symptoms score, AMS, were also improved. Most impressive were the improvements in the parameters of the metabolic syndrome; they all improved and appeared largely correlated (i.e., decline in waist circumference with declines of plasma cholesterol and LDL and increase in plasma HDL). Sex hormone binding globulin, SHBG, may be considered as an indicator of the severity of the metabolic syndrome; levels of SHBG initially fell, probably as a result of rising plasma T levels. But over the last six months of the observation period when plasma T rose further, there was a significant increase in plasma SHBG which may be interpreted to indicate an improvement of the metabolic syndrome. Blood pressure improved slightly but significantly. In this cohort of elderly men (54-76 years; median 64 years) there were no safety concerns over a one year period of T administration. Prostate specific antigen, PSA, levels remained stable; the International Prostate Symptoms Score, IPSS, improved slightly. Liver functions and plasma glucose remained stable. Hemoglogin and hematocrit values increased significantly but remained within reference values.