Cardiovascular Drug Interactions

Abstract

), ). Interactions that decrease a drug's effect leave the patient susceptible to the morbidity and mortality of his primary disease. Interactions that increase a drug's effect may cause toxicity. The narrow benefit:risk ratio of many of the cardiovascular agents increases the impor­ tance of drug interactions involving them, for interactions can result in sub­ therapeutic or toxic responses from doses that would ordinarily be therapeutic. Though the sequelae of cardiovascular drug interactions are often serious, they often are not recognized (1-5). Many patients with cardiovascular diseases are desperately ill, and the manifestations of drug toxicity may be difficult to distinguish from those ofthe primary disease. For example, arrhythmias due to digitalis toxicity may be impossible to differentiate from those that are disease induced (6-9). Simi­ larly, arrhythmias may be a toxic manifestation of antiarrhythmic drugs, and may be misinterpreted as lack of efficacy of the drug (10-14). Avoidance of and appropri­ ate response to drug interactions requires understanding of the pharmacology of the drugs and the pathophysiology of the diseases in which they are used. We categorize drug interactions in pharmacokinetic terms and by types. of drug. The breadth of this topic and editorial limitations on manuscript length allow us only to use broad outlines here. The references listed will help those who wish to pursue topics in more detail.