Decreased effects of acetaminophen, adrenocorticoids, glucocorticoid & mineralocorticoid or corticotropin, cyclosporin, dacarbazine, digitalis glycosides, levothyroxine, quinidine, coumarin or indandione-derivative anticoagulants. Increased risk of habituation w/ other addictive drugs especially CNS depressants w/ habituating potential. Increased risk of hepatotoxicity w/ chronic use prior to enflurane, halothane or methoxyflurane anesth. Increased risk of nephrotoxicity prior to methoxyflurane anesth. Hydantoin anticonvulsants. Enhanced CNS depression w/ TCAs. Increased urinary excretion w/ ascorbic acid. Ca-channel blocking agents. Increased metabolism leading to decreased serum conc & reduced elimination t½
of carbamazepine. Carbonic anhydrase inhibitors. Increased CNS depression w/ other CNS depression-producing drugs. Estrogen-containing OCs, cyclophosphamide, disopyramide. Aggravated orthostatic hypotension w/ loop diuretics or guanadrel/guanethidine. Increased CNS depression & neurological toxicity w/ divalproex Na or valproic acid. Doxycycline. Decreased elimination t½
of fenoprofen. Decreased absorption of griseofulvin. Haloperidol. Increased risk of hypothermia w/ other hypothermia-producing drugs. Increased risk of hypotension &/or resp depression w/ ketamine. Leucovorin, loxapine, phenothiazines or thioxanthenes, maprotiline. Increased serum conc w/ methylphenidate. Accelerated metabolism & decreased plasma conc of mexiletine. Prolonged CNS depressant effects w/ MAOIs including furazolidone, pargyline & procarbazine. Increased risk of cardiac arrhythmias & coronary insufficiency w/ posterior pituitary. Primidone. Reduced effects w/ vit D. Xanthines eg, aminophylline, caffeine, oxtriphylline, theophylline.