title: Cimetidine: interaction with oral anticoagulants in man.
abstract: In 6 patients anticoagulated with warfarin, nicoumalone, or phenindione the addition of cimetidine prolonged the prothrombin-time (PT) by a mean of 12.6 s (range 5--23 s). In 7 volunteers taking daily subtherapeutic doses of warfarin the addition of cimetidine increased the PT from 19.4 to 22.9 s and the plasma-warfarin concentration from 0.96 to 1.76 microgram/ml. Cimetidine reduced the single-dose clearance of warfarin and antipyrine. The basis of the interaction between cimetidine and oral anticoagulants is probably inhibition of drug metabolism. Care should be exercised in concomitant therapy.
mesh_terms: D000074:Acenocoumarol / Q000008:administration & dosage / Q000378:metabolism*; D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000983:Antipyrine / Q000378:metabolism; D001682:Biological Availability; D002927:Cimetidine / Q000494:pharmacology* / Q000627:therapeutic use; D002986:Clinical Trials as Topic; D004357:Drug Synergism; D005260:Female; D006146:Guanidines / Q000494:pharmacology*; D006207:Half-Life; D006801:Humans; D008297:Male; D008875:Middle Aged; D010630:Phenindione / Q000008:administration & dosage / Q000378:metabolism*; D011517:Prothrombin Time; D014859:Warfarin / Q000008:administration & dosage / Q000378:metabolism*
chemical_list: D006146:Guanidines; D010630:Phenindione; D014859:Warfarin; D002927:Cimetidine; D000074:Acenocoumarol; D000983:Antipyrine