1. Which of the following drug interactions could be lethal?

1. Benzodiazepine and Statin - the statin increases benzodiazepine absorption
2. Cholestyramine and Coumadin - the resin decreases action of the Coumadin.
3. Statin and Gemfibrozil - In combination they can cause rhabdomyolysis
4. Statin and Ketoconazole - ketoconazole increases hepatotoxicity of the statin.

Answer: The lethal drug reaction in the following is (b). The Cholestyramine can reduce PT and lead to a prothrombotic state. As most of the these patients are on a oral anticoagulant to prevent serious thrombotic complications this is probably the most important among the drug interactions mentioned. Statin when combined with Gemfibrozil can cause rhabdomyolysis but it is rare and responds well to adequate hydration and conservative management.