We review current knowledge on the rectal, buccal, and sublingual routes of
narcotic administration as potential alternatives to oral, intramuscular, intravenous, and subcutaneous administrations of
narcotics for the management of
cancer pain. Most of the experience reported in the literature is based on the use of rectal, sublingual, and buccal
narcotics for the management of
acute pain syndromes. Preliminary evidence suggests that both
morphine sulfate and chlorhydrate can be administered rectally because there is acceptable absorption with this route even if considerable interpersonal variation exists. There are no controlled trials on the long-term use of rectal
morphine for
cancer pain. There are very few reports on the clinical effects of sublingual and buccal
morphine, and pharmacokinetic data are often debatable. There is evidence to justify further research into all three routes of
narcotic administration. At the moment rectal use is justified in clinical trials in
cancer patients, but there are not enough data on the pharmacokinetics of different
narcotics when administered by the buccal or sublingual routes.