Histan Drug Interactions

Hydroxyzine may be additive with, or may potentiate the action of other CNS depressants (e.g. opiates or other analgesics, barbiturates or other sedatives, anesthetics, or alcohol). When Hydroxyzine is used concomitantly with other CNS depressants, caution should be used to avoid excessive sedation, and recommend that dosage of the CNS depressant can be reduced by up to 50%. Hydroxyzine has been shown to inhibit and reverse the vasopressor effect of epinephrine. If a vasopressor agent is required in patients receiving Hydroxyzine, norepinephrine or metaraminol should be used but epinephrine should not be used. Potent inhibitors of alcohol dehydrogenase or CYP3A4/5 may increase blood concentrations of Hydroxyzine. Hydroxyzine is an inhibitor of CYP2D6 which may lead to additive effects with some substrates of this isoenzyme.
Concomitant administration of Hydroxyzine with drugs known to prolong the QT interval and/or induce torsade de pointes such as class III antiarrhythmics (e.g. amiodarone, sotalol), some antidepressants (e.g. citalopram), some antibiotics (e.g. sparfloxacin), methadone etc., should be avoided. Additive anticholinergic effects may also occur when Hydroxyzine is administered concomitantly with other anticholinergic agents.