BIOAVAILABILITY OF MORPHINE AFTER ADMINISTRATION OF A NEW BIOADHESIVEBUCCAL TABLET

A new bioadhesive buccal morphine tablet was developed for controlled release delivery of drug and improved bioavailability compared with or al controlled release tablet, in order to characterize the pharmacokin etic properties of this bioadhesive buccal formulation, a bioavailabil ity study was performed in 12 healthy volunteers who received: a 30 mg oral controlled release tablet (A); a 20 mg aqueous solution retained in the mouth for 10 min (B); and the 60 mg bioadhesive buccal tablet placed between the lower gum and lip for 6 h (C). The mean amount of m orphine absorbed from the solution was very low, only 2 mg of the 20 m g dose. After administration of forms A and C, plasma levels exhibit t ypical sustained release Concentration-time curves. The mean amount of drug recovered from the residual bioadhesive buccal tablet after 6 h indicated that approximately 50% of the dose was released from the bio adhesive buccal tablet. The relative bioavailability of the buccal tab let (corrected for residual unabsorbed dose) compared with the control led-release tablet was 98% based on the morphine AUC values. Good corr elations between the AUC and the C-max of the bioadhesive tablet for t he drug and metabolite plotted versus the amount of morphine absorbed were found. (C) 1998 John Wiley & Sons, Ltd.