Lack of effect of tacrine administration on the anticoagulant activity of warfarin

J Clin Pharmacol. 1995 May;35(5):526-8. doi: 10.1002/j.1552-4604.1995.tb04099.x.


The effect of tacrine administration on prothrombin time was studied in 13 patients receiving prolonged warfarin therapy. After a 3-week baseline period and 5 days of placebo administration, patients received 20 mg tacrine four times daily for 5 days. Prothrombin times were determined during baseline, daily before the morning doses of placebo and tacrine, and 14 days after the last tacrine dose (closeout). Mean (+/- SD) prothrombin times were 16.2 +/- 2.8 seconds at baseline, 15.1 +/- 2.6 seconds during the placebo phase, 15.8 +/- 3.6 seconds during the tacrine phase, and 15.3 +/- 3.6 seconds at closeout, indicating that tacrine has no effect on the anticoagulant activity of warfarin. Alteration of warfarin dosage should not be required in patients receiving concurrent tacrine therapy.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Drug Administration Schedule
  • Female
  • Humans
  • Male
  • Middle Aged
  • Prothrombin Time*
  • Tacrine / administration & dosage
  • Tacrine / pharmacology*
  • Time Factors
  • Warfarin / pharmacology*


  • Tacrine
  • Warfarin