Not to be used w/ MAOIs. Reduced analgesic effect & duration of action w/ carbamazepine. Increased risk of convulsions w/ SSRIs, SNRIs, TCAs, antipsychotics & other seizure threshold-lowering medications eg, bupropion, mirtazapine, tetrahydrocannabinol. Serotonin syndrome w/ SSRIs, SNRIs, MAOIs, TCAs & mirtazapine. Increased INR w/ coumarin derivatives eg, warfarin. Inhibited metabolism w/ CYP3A4 inhibitors eg, ketoconazole & erythromycin. Increased requirement w/ pre- & post-op use of ondansetron in patients w/ post-op pain. Potentiated CNS effects w/ centrally-depressant drugs eg, alcohol. Increased risk of sedation, resp depression, coma & death w/ benzodiazepines or related drugs. Precipitation w/ diazepam, diclofenac Na, indomethacin, midazolam, piroxicam.