A clinically significant drug interaction between antidepressants and beta-blockers has been examined in research from in the United States. The inhibition of the CYP2D6 hepatic isoenzyme by various antidepressants can result in increased plasma concentrations of beta-blockers when administered simultaneously, leading to serious adverse events including hypotension, bradycardia and falls. The research involved a survival plot analysis examining 21,292 participants receiving beta-blockers that are CYP2D6 substrates (such as metoprolol, propranolol & carvedilol), spanning the period between 2004 and 2012. 4.3% of patients were hospitalised or taken to an emergency department (ED) within 30 days of concomitant administration. The risk for hospitalisation or ED visits was greater among patients receiving antidepressants with moderate-strong CYP2D6 inhibition (such as fluoxetine, paroxetine, duloxetine & bupropion) than in patients receiving antidepressants with weak CYP2D6 inhibition for ≤ 30 days. Demographic factors linked to increased morbidity were advanced age, male sex, higher doses of beta-blocker and African-American race or Hispanic ethnicity.  Further details of this metabolic drug interaction study can be accessed here.

Contributed by Australian Medication Safety Services Associate – Isabella Singh