Comparative morphine pharmacokinetics following sublingual, intramuscular, and oral administration in patients with cancer.

Previous literature reports have suggested that sublingually administered morphine sulfate results in an improved bioavailability of the drug when compared to orally administered morphine. To investigate this possibility further, we studied six cancer patients all of whom received 10 mg doses of morphine sulfate by intramuscular, oral and sublingual routes. Pharmacokinetic analyses failed to suggest an advantage of sublingual administration when compared with oral dosing. Bioavailability of morphine following intramuscular administration appeared superior to both oral and sublingual routes.