title: Explanation for potency of repeated oral doses of morphine?
abstract: Morphine given by injection is the standard by which all other strong analgesics are measured, but when given orally in single doses it is a poor analgesic. With repeated oral administration it becomes very effective and it may be that on repeated dosage active metabolites, particularly morphine-6-glucuronide, account for much of the analgesic activity. Enterohepatic circulation may also contribute to the maintenance of blood and tissue levels of morphine and its metabolites in chronic use.
mesh_terms: D000284:Administration, Oral; D002908:Chronic Disease; D004341:Drug Evaluation; D006801:Humans; D009020:Morphine / Q000008:administration & dosage* / Q000493:pharmacokinetics / Q000494:pharmacology; D010146:Pain / Q000188:drug therapy*
chemical_list: D009020:Morphine