Isoniazid Enflurane

Drugs that may interact with isoniazid include acetaminophen, carbamazepine, chlorzoxazone, disulfiram, enflurane, hydantoins, ketoconazole, rifampin, and theophylline. 

CYP2E1 Enflurane, halothane Alcohol (chronic), isoniazid Disulfiram... 

E1 Acetaminophen, chlorzoxazone, enflurane, halothane, ethanol (a minor pathway) Ethanol, isoniazid 4-Methylpyrazole, disulfiram... 

E1 Chlorzoxazone, isoniazid, acetaminophen, halothane, enflurane, methoxyflurane Dimethylnitrosamine, benzene, halogenated alkanes (eg, CCLj) acylonitrile, alcohols, aniline, styrene, vinyl chloride Chlorzoxazone (6-OH), [p-nitrophenol]... 

Isoniazid Isoniazid is incompatible with sugars. Isoniazid overdose may be severe to fatal, and treatment is symptomatic and supportive, including stomach wash for control of convulsions and treating metabolic acidosis. Administration of pyridoxine and hemodialysis may be needed. Isoniazid interacts with carba-mazepine, phenytoin, diazepam, triazolam, chlorzoxazone, theophylline, ethosux-imide, enflurane, cycloserine, and warfarin. 

Mazze Rl, Woodruff RE, Heerdt ME. Isoniazid-induced enflurane defluorination in humans. Anesthesiology 1982 57(1) 5-8. 

Consistent with its blood gas partition coefficient, induction of anesthesia and recovery from enflurane are relatively slow (Table 13-1). Enflurane is metabolized to a modest extent (2-8% of absorbed enflurane) by hepatic CYP2E1. Fluoride ions are a by-product of enflurane metabolisrrr but plasma fluoride levels are low and nontoxic. Patients taking isoniazid exhibit enhanced metabolism of enflurane with a consequent elevation of serum fluoride. 

Isoniazid may increase the metabolism of enflurane, isoflurane or sevoflurane and thereby increase plasma-fluoride concentrations. However, this does not seem to have resulted in clinically important renal impairment. 

When enflurane was given to 20 patients who had been taking isoniazid 300 mg daily for between one week and one year, 9 had an increase in peak fluoride ion levels. These 9 patients had a fourfold higher fluoride level than 36 control subjects not taking isoniazid and the 11 other subjects taking isoniazid. By 48 hours after anaesthesia, there was no difleience in fluoride levels. Despite the increase in fluoride levels, there was no change in renal function. ... 

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