Drug Interactions of Medications Commonly Used in Diabetes

Abstract

When patients are diagnosed with diabetes, a large number of medications become appropriate therapy. These include medications for dyslipidemia, hypertension, antiplatelet therapy, and glycemic control. So many medications can be overwhelming, and it is imperative that patients are thoroughly educated about their drug regimen. Patients have many concerns when multiple medications are started, including prescribing errors, the cost of medications, and possible adverse effects. Significantly, 58% of patients worry that they will be given medications that have drug interactions that will adversely affect their health.1 These worries are not unfounded given that several highly publicized drugs have been withdrawn from the U.S. market in the past several years because of adverse effects from drug interactions. Terfenadine, mibefradil, and cisapride have all been withdrawn from the market specifically because of drug-drug interactions. When terfenadine or cisapride were given with a strong inhibitor of their metabolism, torsades de pointes, a life-threatening drug-induced ventricular arrhythmia associated with QT prolongation, could occur.2 Cisapride, for gastroparesis or gastrointestinal reflux disease, and mibefradil, for hypertension, were prescribed for many patients with diabetes. An adverse drug interaction is defined as an interaction between one or more coadministered medications that results in the alteration of the effectiveness or toxicity of any of the coadministered medications. Drug interactions can be caused by prescription and over-the-counter medications, herbal products or vitamins, foods, diseases, and genetics (family history). The true incidence of drug interactions is unknown because many are not reported, do not result in significant harm to patients, or do not require admission to a hospital. When a hospitalization does occur, it is usually not documented as a drug interaction, but rather as an adverse drug reaction because the drug interaction may only be one component of the reason for admission.3,4 Although drug interactions for …