title: Age as a determinant of sensitivity to warfarin.
abstract: 1 Parallel human and rat studies were carried out to confirm the previous suggestion of an increased sensitivity to warfarin in old age. 2 The anticoagulant response to warfarin was found to be greater in the elderly groups despite, in the case of the patient study, the elderly subjects being given a smaller weight-related dose. 3 At the same plasma warfarin concentrations there was greater inhibition of vitamin K-dependent clotting factor synthesis in the elderly. There was no difference in the rate of clotting factor degradation in the two age groups. 4 There was no appreciable difference in warfarin pharmacokinetics (plasma half-life, apparent volume of distribution, plasma clearance, plasma protein binding or plasma warfarin alcohol levels) in the two age groups. 5 There appeared to be no major age-related differences in warfarin pharmacokinetics and the increased effect of warfarin in the elderly seemed to result from an increased intrinsic sensitivity to warfarin.
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging; D000818:Animals; D001777:Blood Coagulation / Q000187:drug effects*; D001779:Blood Coagulation Factors / Q000378:metabolism; D001798:Blood Proteins / Q000378:metabolism; D006207:Half-Life; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D011485:Protein Binding; D051381:Rats; D013997:Time Factors; D014859:Warfarin / Q000097:blood / Q000494:pharmacology*
chemical_list: D001779:Blood Coagulation Factors; D001798:Blood Proteins; D014859:Warfarin