Calcium channel blockers + macrolides: elderly patients hospitalised for low blood pressure

Prescrire Int. 2012 Jul;21(129):182.

Abstract

Macrolides that inhibit cytochrome P450 isoenzyme CYP 3A4 can lead to the accumulation of calcium channel blockers metabolised by the same isoenzyme and therefore an increase in their dose-related adverse effects. A Canadian case-control study examined the relationship between macrolide use and hospitalisation for hypotension (including shock) among 7100 elderly patients who were also taking a calcium channel blocker. The results showed more exposure to certain macrolides immediately prior to hospitalisation for hypotension than during an earlier control period; these macrolides included erythromycin (odds ratio (OR) = 5.8; 95% confidence interval: 2.3 to 15) and clarithromycin (OR = 3.7, 95% CI: 2.3 to 6.1). No such increase was found with azithromycin. In practice, patients treated with a calcium channel blocker should not be prescribed erythromycin or clarithromycin, but rather an antibiotic with similar efficacy but a lower risk of interaction.

MeSH terms

  • Aged
  • Anti-Bacterial Agents / pharmacology*
  • Calcium Channel Blockers / adverse effects*
  • Clarithromycin / pharmacology
  • Cytochrome P-450 CYP3A
  • Cytochrome P-450 CYP3A Inhibitors
  • Drug Interactions
  • Erythromycin / pharmacology
  • Hospitalization
  • Humans
  • Hypotension / chemically induced*
  • Macrolides / pharmacology*

Substances

  • Anti-Bacterial Agents
  • Calcium Channel Blockers
  • Cytochrome P-450 CYP3A Inhibitors
  • Macrolides
  • Erythromycin
  • Cytochrome P-450 CYP3A
  • CYP3A4 protein, human
  • Clarithromycin