Lack of effect of food on the pharmacokinetics of an extended-release oxybutynin formulation.

The effect of food on the pharmacokinetics of 15 mg oxybutynin XL was evaluated in a single-dose, randomized, crossover, open-label study in healthy volunteers. A validated, stereospecific, high-performance liquid chromatography assay was used to simultaneously determine the plasma concentrations of R- and S-oxybutynin and active metabolite R- and S-desethyloxybutynin. The mean AUC and Cmax values for each of the four analytes in the fed treatment were within +/- 20% of the fasting treatment values. The 90% confidence intervals for the treatment ratios (fed/fasted) for log-transformed Cmax and AUCinf values for the drug isomers and AUCinf values for the metabolite isomers were all within the 80% to 125% range. Only the ranges for the Cmax values for R- and S-desethyloxybutynin were slightly wider but were well within the 70% to 143% criteria recommended for Cmax when comparing effect of food. Lack of effect of food on oxybutynin XL is consistent with the previous observation that the osmotically controlled formulations are nearly insensitive to the gastrointestinal environment, including food. Oxybutynin XL was well tolerated, and the safety results were comparable whether administered alone or with food. In conclusion, oxybutynin XL administration does not require any caution to be exercised regarding food.

RCT Entities:   Population Interventions Outcomes