Increased risk of seizures & serotonin syndrome w/ MAOIs eg, phenelzine, tranylcypromine, linezolid. Tramadol: Increased risk of adverse events including seizures & serotonin syndrome w/ serotonergic drugs (eg, SSRIs, SNRIs, TCAs, triptans, 5-HT
3 receptor antagonists, drugs that affect serotonin neurotransmitter system including mirtazapine & trazadone, & muscle relaxants eg, cyclobenzaprine, metaxalone). Decreased plasma conc of tramadol w/ CYP3A4 inducers (eg, rifampin, carbamazepine, phenytoin) resulting in decreased efficacy or onset of w/drawal syndrome in patients who have developed physical dependence to tramadol. May increase plasma conc of tramadol w/ CYP2D6 inhibitors eg, quinidine, fluoxetine, paroxetine, amitriptyline, & bupropion. Increased plasma conc of tramadol & may result in greater amount of metabolism w/ CYP3A4 inhibitors eg, macrolides including erythromycin, azole-antifungal agents including ketoconazole, PIs including ritonavir. May produce additive CNS depressant effects (eg, profound sedation & resp depression) w/ benzodiazepines & other CNS depressants including alcohol (eg, other sedatives/hypnotics, tranquilizers, muscle relaxants, general anesth, other opioids). Increased coagulation time (INR) w/ warfarin. Paracetamol: Report of high anion gap metabolic acidosis from pyroglutamic acid (5-oxoprolinemia) w/ flucloxacillin. Absorption rate may be increased w/ metoclopramide or domperidone. Reduced absorption w/ cholestyramine.