Increasing circulating androgens with oral testosterone undecanoate in eugonadal men.

The effects of oral testosterone undecanoate (TU 80 mg; Organon) on plasma testosterone was assessed in 9 men (average age 55 yrs) complaining of loss of sexual interest. Absorption tests were carried out following the first dose of TU and again after 3 or 4 weeks of chronic administration. Absorption was variable in timing, peaks occurring from 30 min to 5 1/2 h after the oral dose. Increases in plasma testosterone of at least 50% of baseline levels occurred in 14 of the 18 tests. Apart from a slightly faster metabolic clearance on the second test, associated with a significant reduction in SHBG, there were no other significant differences between the first and second absorption tests. Variability of absorption may be related to dietary factors. If this can be reduced by dietary control, TU offers distinct advantages over injectable esters and implants in the short-term administration of testosterone to eugonadal men.