<p>Increased metabolism and toxicity with drugs that induce CYP2E1 isoenzyme (e.g. isoniazid). Reduced MAC with benzodiazepines, opioids. May cause ventricular arrhythmia with &beta;-sympathomimetic agents (e.g. isoprenaline), and &alpha;- and &beta;-sympathomimetic agents (e.g. adrenaline, noradrenaline). May cause crisis during operation with nonselective MAO inhibitors. May lead to marked hypotension and risk of additive negative inotropic effect with Ca antagonists (esp dihydropyridines).</p>