Low-dose warfarin decreases coagulability without affecting prothrombin complex activity.
OBJECTIVE
To assess the efficacy of a fixed, low dose of warfarin in lowering factor VII coagulant activity (FVII:C) and to investigate the effects on the plasma coagulation cascade.


METHODS
An open pilot study with two dose levels of warfarin: 1.25 and 2.5 mg day-1 during two consecutive 4-week periods. All subjects received aspirin 75 mg day-1. Prothrombin fragment 1 + 2 (F(1 + 2)), protein C, protein S, FVII:C, factor X and P-prothrombin complex activity (P-PT) were measured at baseline, at 2-week intervals and 4 weeks after end of treatment. Coagulation activation peptide F(1 + 2) was used as a marker of thrombin formation.


METHODS
Twelve male patients with a history of myocardial infarction. Inclusion was made through a written questionnaire.


RESULTS
Warfarin 1.25 mg day-1 lowered FVII:C from 113 U dl-1 to 107 U dl-1 (P = 0.025) and F(1 + 2) from 1.60 nmol l-1 to 1.27 nmol l-1 (P = 0.013) but had no effect on protein C or P-PT. A dose of 2.5 mg day-1 induced further lowering of FVII:C (91 U dl-1, P = 0.0042), and also of protein C from 116% to 99% (P = 0.034) and P-PT from 107% to 81% (P = 0.0096) mean values.


CONCLUSIONS
Warfarin 1.25 mg day-1 seems to exert an anticoagulant effect without reduction in PT or the natural anticoagulant protein C and is suggested, in combination with aspirin, to be a safe and simple therapy against arterial thrombotic disease, making regular PT controls unnecessary.
Holm
J
J
Department of Medicine, Lund University, Malmö General Hospital, Sweden.
Berntorp
E
E
Carlsson
R
R
Erhardt
L
L
D000328:Adult; D000368:Aged; D000941:Antigens / Q000187:drug effects; D001777:Blood Coagulation / Q000187:drug effects*; D005167:Factor VII / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000187:drug effects; D010865:Pilot Projects; D011486:Protein C / Q000187:drug effects; D017293:Protein S / Q000187:drug effects; D011516:Prothrombin / Q000187:drug effects*; D013997:Time Factors; D014859:Warfarin / Q000008:administration & dosage / Q000494:pharmacology*
D000941:Antigens; D010446:Peptide Fragments; D011486:Protein C; D017293:Protein S; C042580:factor VII clotting antigen; C045879:prothrombin fragment 1.2; D014859:Warfarin; D005167:Factor VII; D011516:Prothrombin