Central nervous system toxicity associated with concurrent use of triazolam and cimetidine

A 49-year-old woman treated with cimetidine 300 mg tid for more than 18 months for Zollinger-Ellison syndrome experienced lethargy, dizziness, ataxia, and auditory and visual hallucinations after receiving triazolam 0.375 mg hs for sleep. Triazolam plasma concentrations were measured, and a triazolam elimination half-life was calculated to be approximately 8 hours (reported range 1.7-3 h). Cimetidine has been reported to decrease the apparent oral clearance of triazolam, resulting in increased triazolam plasma concentrations with the potential for exaggerated triazolam pharmacologic effects. Cimetidine may have been responsible for the unusually large elimination half-life in this patient. Until the mechanisms and clinical significance of this potential drug interaction are determined, clinicians should use the combination of triazolam and cimetidine with caution.