EFFECT OF FOOD ON THE BIOAVAILABILITY OF OXYBUTYNIN FROM A CONTROLLED-RELEASE TABLET

Objective: The effect of food on the bioavailability of oxybutynin was assessed in a randomised cross-over study in 23 healthy volunteers. A single oral 10 mg dose of a controlled release oxybutynin tablet was administered after a high fat breakfast and to fasting subjects. The A UG, C-max, t(max), t(1/2) and MRT of oxybutynin and its active metabol ite N-desethyloxybutynin were determined. Results: Breakfast did not c hange the AUC of oxybutynin but increased the AUC of N-desethyloxybuty nin by about 20 %. The C-max of oxybutynin and N-desethyl oxybutynin w ere two-fold higher when the drug was administered after breakfast com pared to the fasting state. Conclusion: Breakfast significantly reduce d the MRT of oxybutynin and N-desethyloxybutynin.