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:
Increase the dose of warfarin
Replace warfarin with acenocoumarin
Switch ethambutol for rifampicin
Use LMW heparin
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
Hematology