Effect of food on the oral bioavailability of didanosine from encapsulated enteric-coated beads

The objective of this study seas to assess the effect of food and timing of meals on the bioavailability of didanosine from encapsulated enteric-coated beads. Four different independent, open-label, single-dose, randomized, crossover studies were conducted in healthy subjects (n = 20-30). Didanosine (400 mg) was given concomitantly with a high fat meal, lightmeal, yogurt, and applesauce. In addition, didanosine was given 1, 1.5, 2, and 3 hours before and 2 hours after a light meal. Statistical comparison with fasting conditions was made using the equivalence approach for Cm. (70%0-143%) and AUC (80%-125%). The high fat meal, light meal, yogurt, and applesauce decreased the C-max, by 46%,22%,30%, and 24%0, respectively, and lowered the AUC by 19%, 27%, 20%, and 18%, respectively; statistical analyses indicated an indeterminate food effect, except for the C-max, for the high fat meal. a For l hour before meal, Cm.,, and AUC were lower by 15% and 24% and, for 2 hours after meal, were lower by15% and 10%, respectively. There was an indeterminate food effect for 1hour before the meal treatment; in addition, 2 hours after the en- meal, treatment approached statistical equivalence, missing narrowly on the lower bounds. For 1.5, 2, and 3 hours before meal treatments, C-max values were unchanged, but AUC was lower by 10%, 4%, and 0%, respectively; lack of food effect was observed for all three treatments. Across studies, median time to C-max ranged from 1.67 to 2.67 hours but was delayed by 2.5 to 3 hours with high-fat and light meals compared fasting conditions. The half-life of didanosine was 1.5 to 2 hours. It was concluded that the bioavailability of didanosine from encapsulated enteric-coated beads was reduced by approximately 20% to 25% with food, which can be circumvented by taking didanosine on an empty stomach. The clinical significance of such moderate reductions in didanosine exposure with food, especially as part of a highly active antiretroviral therapy, is not clear.