Interaction between midazolam and clarithromycin in the elderly

Sara K. Quinney, Barbara D. Haehner, Melissa B. Rhoades, Zhen Lin, J. Christopher Gorski, Stephen D. Hall

Research output: Contribution to journalArticle

34 Scopus citations


AIM: To assess the relative contribution of intestinal and hepatic CYP3A inhibition to the interaction between the prototypic CYP3A substrate midazolam and clarithromycin in the elderly. METHODS: On day 1, 16 volunteers (eight male, eight female) aged 65-75 years weighing 59-112 kg received simultaneous doses of midazolam intravenously (i.v.) (0.05 mg kg-1 over 30 min) and orally (p.o.) (3.5 mg of a stable isotope, 15N3-midazolam) . Starting on day 2, clarithromycin 500 mg was administered orally twice daily for 7 days. On day eight, i.v. and p.o. doses of midazolam were administered 2 h after the final clarithromycin dose. Serum and urine samples were assayed for midazolam, 15N3-midazolam and metabolites by gas chromatography/mass spectometry. RESULTS: Men and women exhibited similar i.v. (30.4 vs. 36.0 l h-1) and p.o. (119 vs. 124 l h-1) clearances of midazolam. Midazolam hepatic availability was significantly (P = 0.006) greater in men [0.79, 95% confidence interval (CI) 0.75, 0.84] than in women (0.66, 95% CI 0.59, 0.73), but midazolam intestinal availability (0.39 vs. 0.55) was not different. Following clarithromycin dosing, a significant decrease in systemic (33.2 l h-1 to 11.5 l h-1) and oral (121 l h-1 to 17.4 l h-1) midazolam clearance occurred. Oral, hepatic and intestinal availability was significantly increased after clarithromycin dosing from 0.34 to 0.72, 0.73 to 0.91 and 0.47 to 0.79, respectively. Clarithromycin administration led to an increase in the AUC of midazolam by 3.2-fold following i.v. dosing and 8.0-fold following p.o. dosing. Similar effects were observed for males and females. CONCLUSIONS: Intestinal and hepatic CYP3A inhibition by clarithromycin significantly reduces the clearance of midazolam in the elderly.

Original languageEnglish (US)
Pages (from-to)98-109
Number of pages12
JournalBritish Journal of Clinical Pharmacology
Issue number1
StatePublished - Jan 2008


  • Clarithromycin
  • CYP3A
  • Cytochrome P450
  • Elderly
  • Midazolam

ASJC Scopus subject areas

  • Pharmacology (medical)
  • Pharmacology, Toxicology and Pharmaceutics(all)

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