Dietary fat modulates the testosterone pharmacokinetics of a new self-emulsifying formulation of oral testosterone undecanoate in hypogonadal men.

This study investigates the effect of dietary fat on the testosterone (T) pharmacokinetics in hypogonadal men following administration of a self-emulsifying capsule formulation of oral T undecanoate (TU). In an open-label, 2-center, 5-way crossover study, a single oral dose of TU containing 300-mg equivalents of T (maximum anticipated human dose per administration) was administered to 16 hypogonadal men with a washout period of at least 5 days between doses. All participants were randomized to receive the TU capsules fasting or 30 minutes after an approximately 800-calorie meal containing 10%, 20%, 30%, or 50% fat. Serial blood samples were collected from 2 hours predose to 25 hours postdose to determine serum T and dihydrotestosterone (DHT) by liquid chromatography tandem mass spectrometry. Administering TU with a meal increased serum T concentrations, with the magnitude of the increase being directly dependent on the amount of fat in the meal. Average and peak serum T concentrations and area under the curve increased as the fat content of the meal was increased. Neither the high-fat meal (50% fat) nor the lower-fat meal (20% fat) showed a significant food effect relative to the normal-fat (Western diet) meal (30% fat). However, administering TU while fasting resulted in 50% or less of the cumulative exposure obtained when administered with 20%- to 50%-fat meals (albeit still substantial). A very-low-fat meal (10% fat) showed a significant food effect relative to the normal meal, but still exceeded the fasting condition by approximately 50%. Serum DHT concentrations showed corresponding increases to the serum T. As expected with the maximum anticipated clinical dose of TU (300 mg T), oral administration of this new formulation with food containing 20% to 50% dietary fat produced T levels at or above the upper range of adult men, and T levels trended higher as dietary fat content increased. Only with a very-low-fat diet (10%) or in a fasted state did a clinically significant food effect occur, but even then sufficient TU was absorbed with the self-emulsifying TU formulation to produce average serum T concentration predicted to be in the normal reference range (10 to 35 nmol/L).