title: Hypotension induced by the concomitant use of a calcium-channel blocker and clarithromycin.
abstract: In the elderly, calcium-channel blockers are the first-line treatment for hypertension, and macrolides are commonly prescribed antibiotics. Here we report a 78-year-old man taking nifedipine, diltiazem and carvedilol who presented with persistent hypotension and bradycardia after clarithromycin was prescribed. He was diagnosed with drug-induced hypotension and treated with fluid resuscitation and vasoactive agents. His symptoms gradually improved. He was transferred out of the intensive care unit 3 days after hospitalisation. Combining calcium-channel blockers and clarithromycin can cause vasodilatory hypotension. The concomitant use of calcium-channel blockers and macrolide antibiotics increases the levels of calcium-channel blockers in the blood as they are metabolised by cytochrome P450 3A4 (CYP3A4), which is inhibited by macrolide antibiotics. Moreover, the addition of another calcium-channel blocker and a β blocker can lower cardiac output due to bradycardia and worsen hypotension. Therefore, it is important to consider drug interactions when the cause of hypotension is unknown.
authors.affiliation: Department of Critical Care Medicine, Japanese Red Cross Society Wakayama Medical Center, Wakayama, Japan.
authors.forename: Sayako
authors.initials: S
authors.lastname: Takeuchi
authors.affiliation: Department of Critical Care Medicine, Japanese Red Cross Society Wakayama Medical Center, Wakayama, Japan.
authors.forename: Yuki
authors.identifier: http://orcid.org/0000-0002-9532-2859
authors.initials: Y
authors.lastname: Kotani
authors.affiliation: Department of Critical Care Medicine, Japanese Red Cross Society Wakayama Medical Center, Wakayama, Japan.
authors.forename: Toshihide
authors.initials: T
authors.lastname: Tsujimoto
mesh_terms: D000368:Aged; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000009:adverse effects*; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000009:adverse effects*; D017291:Clarithromycin / Q000008:administration & dosage / Q000009:adverse effects*; D003937:Diagnosis, Differential; D004347:Drug Interactions; D004562:Electrocardiography; D006801:Humans; D007022:Hypotension / Q000139:chemically induced*; D008297:Male
chemical_list: D000900:Anti-Bacterial Agents; D002121:Calcium Channel Blockers; D017291:Clarithromycin