Pharmacokinetics of morphine following administration by the buccal route

The pharmacokinetics of morphine administered via the buccal route as a controlled release formulation were assessed after the administration of three different doses and found to be linear in the dose range 10-30 mg. The plasma concentrations of morphine-3-glucuronide and morphine-6-glucuronide demonstrated considerable inter-subject variation and conclusions could not be drawn regarding their pharmacokinetics. These large differences may reflect not only variability in buccal absorption, but may have resulted from the preparation dissolving in saliva, followed by absorption from the gastrointestinal tract.