depacon and Adapin Interactions

Interactions between depacon(valproic acid) and Adapin (doxepin)

valproic acid and doxepin (Moderate Drug-Drug)

MONITOR: The concomitant administration of valproic acid or its derivatives may increase serum concentrations of tricyclic antidepressants. In one study, the amitriptyline area under the curve was increased 31% in subjects taking divalproex sodium (n=15). A case report has described increased nortriptyline levels and toxicity after sodium valproate was added to the regimen. The proposed mechanism of action is inhibition of CYP450 hepatic metabolism. CNS and/or respiratory depressant effects may be additively or synergistically increased in patients taking multiple drugs which cause these effects. Other tricyclic antidepressants may exhibit a similar interaction. Additionally, tricyclic antidepressants may counteract the anticonvulsive effects of valproic acid and divalproex by lowering the seizure threshold.

MANAGEMENT: It may be advisable to monitor patients for altered efficacy and safety. Dose adjustments or alternate therapy may be necessary if an interaction is suspected.