A diabetic female on INH and rifampicin for TB developed DVT.She was staed on warfarin, PT is not raised, and next step should be:
Rifampicin is a microsomal enzyme inducer and hence enhances the metabolism of warfarin. Hence warfarin can be replaced with a LMWH as the treatment is to stop warfarin. Acenocoumarin is a coumarin derivative similar to warfarin. From medical pharmacology padmaja 4th edition Page no 339,340
Increase the dose of warfarin
Replace warfarin with acenocoumarin
Switch ethambutol for rifampicin
Use LMW heparin
Hematology