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Drug Interactions in the Treatment of Depression in Patients Receiving β-Blocker Drugs

J Clin Psychiatry 2013;74(1):e75-e78

b-Blockers are prescribed for several indications, including ischemic heart disease, hypertension, heart failure, anxiety, migraine, and essential tremor. Some patients receiving b-blockers for 1 or more of these indications may also require treatment with an antidepressant, such as for comorbid depression. Some antidepressants inhibit the metabolism of some b-blockers; for example, fluoxetine, paroxetine, duloxetine, and bupropion can inhibit cytochrome P450 2D6 and thereby increase the levels of metoprolol, carvedilol, and nebivolol. This pharmacokinetic drug interaction can result in clinically significant bradycardia and hypotension, heart block, or other dose-dependent adverse effects in vulnerable patients. The interaction can be avoided by prescribing an antidepressant that does not affect the metabolism of the b-blocker in use, or by prescribing a b-blocker that is not metabolized by the antidepressant in use. If the interaction is unavoidable, the dose of the b-blocker can be down-titrated using heart rate and blood pressure as a clinical guide.