Methaqualone may cause a very small and clinically unimportantreduction in anticoagulant effects of warfarin
Clinical evidence,mechanism, importance and management
20.9 seconds before,20.4 seconds during,and 19.6 seconds after taking methaqualone 300mg at bedtime for 4 weeks (See reference number 1). The plasma warfarin levels of another patient were unaffected by methaqualone,although there was some evidence that enzyme induction had occurred (See reference number 2). Methaqualone has some enzyme-inducing effects so that any small changes in pro-thrombin times reflect a limited increase in metabolism and clearance of warfarin, but these appear to be too small to be of clinical significance (See reference number 2,3). No special precautions seem to be necessary.
Udall JA. Clinical implications of warfarin interactions with five sedatives. Am J Cardiol (1975) 35,67–71.
Whitfield JB,Moss DW, Neale G, Orme M, Breckenridge A. Changes in plasma :5.5pt; font-weight:normal; color:#000000″>γ-glutamyl transpeptidase activity associated with alterations in drug metabolism in man. BMJ (1973) 1, 316–18.
Nayak RK,Smyth RD, Chamberlain AP, Polk A, DeLong AF, Herczeg T, Chemburkar PB,Joslin RS, Reavey-Cantwell NH. Methaqualone pharmacokinetics after single- and multiple-dose administration in man. J Pharmacokinet Biopharm (1974) 2, 107–21.