Drug points: Serious interaction between warfarin and oral terbinafineBMJ 1998; 316 doi: https://doi.org/10.1136/bmj.316.7129.440 (Published 07 February 1998) Cite this as: BMJ 1998;316:440
- J A Warwicka,
- R J Corralla
- a Anticoagulant Clinic, Department of Pharmacy, and Directorate of Medicine, Bristol Royal Infirmary, Bristol BS2 8HW
Drug interactions with warfarin are a common cause of loss of control of anticoagulation. Oral treatment with the antifungal drug griseofulvin decreases the anticoagulant effect of warfarin,1 but, to our knowledge, ours is the first report of an interaction between warfarin and the oral antifungal terbinafine.
A 68 year old woman had taken warfarin for mitral valve disease since 1973. In the two years before November 1995 her daily maintenance dose was 5.5 mg. Monthly measurements of the international normalised ratio were stable at between 2 and 3. She also had non-insulin dependent diabetes mellitus. She took glibenclamide, metformin, frusemide, and spironolactone, the doses of which had not been …