Moderate
Established
Description
Diazepam and diphenhydramine produce additive CNS depression, with risk of profound sedation, cognitive impairment, and falls.
Mécanisme
Diazepam potentiates GABA-A inhibition; diphenhydramine blocks H1 receptors causing sedation and has anticholinergic effects — additive CNS depression occurs.
Signification clinique
Particularly hazardous in elderly patients; both drugs appear on the Beers Criteria as potentially inappropriate in older adults.
Prise en charge
Avoid combination especially in elderly; use non-sedating antihistamines and minimize benzodiazepine duration.