Important effect of food on the bioavailability of oral testosterone undecanoate

Study Objective. To assess the effects of food on the bioavailability of testosterone undecanoate, testosterone, and 5alpha-dihydrotestosterone (DHT) after administration of a new oral testosterone undecanoate formulation, Andriol Testocaps. Design. Randomized, open-label, crossover study with a 1-week washout period. Setting. Clinical pharmacology unit. Subjects. Sixteen healthy postmenopausal women. Intervention. Single oral doses of testosterone undecanoate 80 mg were administered either during a fasting period or after consumption of a standardized continental breakfast. Measurements and Main Results. Serum concentrations of testosterone undecanoate were assayed by liquid chromatography with mass spectrometry detection; testosterone and DHT were assayed by gas chromatography with mass spectrometry detection. Serum concentrations of testosterone, testosterone undecanoate, and DHT were low to negligible when testosterone undecanoate was administered to subjects in a fasting state; these values were significantly higher when the test drug was coadministered with food. For testosterone, the maximum serum concentration and area under the plasma concentration-time curve were 0.67 ng/ml and 5.37 ng.hr/ml, respectively, in the fasting state, versus 10.7 ng/ml and 56.4 ng.hr/ml, respectively, in the fed state. The same parameters were also significantly higher for testosterone undecanoate and DHT in the fed versus fasting subjects. Conclusion. Food increases the bioavailability of testosterone undecanoate, testosterone, and DHT. For proper absorption, Andriol Testocaps must be taken with meals.