<prompt> Which of the following do not increase the action of warfarin?CimetidineIsoniazidRifampicinCotrimoxazole  <response>: Reference: KDT, Essentials of Medical Pharmacology, 7th ed., Pg. 623 and Katzung, Basic Clinical Pharmacology, 13th ed., Pgs. 876 877. Barbiturates but not benzodiazepines, carbamazepine, rifampin and griseofulvin induce the metabolism of oral anticoagulants. The dose of anticoagulant determined during therapy with these drugs would be higher: if the same is continued after withdrawing the inducermarked hypoprothrombinemia can occurfatal bleeding is on record.Metronidazole, fluconazole, and trimethoprim-sulfamethoxazole also stereoselectively inhibit the metabolic transformation of S-warfarin, whereas amiodarone, disulfiram, and cimetidine inhibit metabolism of both enantiomorphs of warfarin. Barbiturates and rifampin cause a marked decrease of the anticoagulant effect by induction of the hepatic enzymes that transform racemic warfarin. 