Disulfiram

DISULFIRAM- disulfiram tablet
Qualitest Pharmaceuticals

WARNING

Disulfiram should never be administered to a patient when he is in a state of alcohol intoxication, or without his full knowledge.
The physician should instruct relatives accordingly.

DESCRIPTION

Disulfiram is an alcohol antagonist drug.

CHEMICAL NAME:
bis(diethylthiocarbamoyl) disulfide.

STRUCTURAL FORMULA:

This is the structural formula for Disulfiram Tablets, USP.
(click image for full-size original)

Disulfiram occurs as a white to off-white, odorless, and almost tasteless powder, soluble in water to the extent of about 20 mg in 100 mL, and in alcohol to the extent of about 3.8 g in 100 mL.

Each tablet for oral administration contains 250 mg or 500 mg disulfiram, USP. Tablets also contain anhydrous lactose, colloidal silicon dioxide, croscarmellose sodium, magnesium stearate, microcrystalline cellulose, and poloxamer.

CLINICAL PHARMACOLOGY

Disulfiram produces a sensitivity to alcohol which results in a highly unpleasant reaction when the patient under treatment ingests even small amounts of alcohol.

Disulfiram blocks the oxidation of alcohol at the acetaldehyde stage. During alcohol metabolism following disulfiram intake, the concentration of acetaldehyde occurring in the blood may be 5 to 10 times higher than that found during metabolism of the same amount of alcohol alone.

Accumulation of acetaldehyde in the blood produces a complex of highly unpleasant symptoms referred to hereinafter as the disulfiram-alcohol reaction. This reaction, which is proportional to the dosage of both disulfiram and alcohol, will persist as long as alcohol is being metabolized. Disulfiram does not appear to influence the rate of alcohol elimination from the body.

Disulfiram is absorbed slowly from the gastrointestinal tract and is eliminated slowly from the body. One (or even two) weeks after a patient has taken his last dose of disulfiram, ingestion of alcohol may produce unpleasant symptoms.

Prolonged administration of disulfiram does not produce tolerance; the longer a patient remains on therapy, the more exquisitely sensitive he becomes to alcohol.

INDICATIONS AND USAGE

Disulfiram is an aid in the management of selected chronic alcohol patients who want to remain in a state of enforced sobriety so that supportive and psychotherapeutic treatment may be applied to best advantage.

Disulfiram is not a cure for alcoholism. When used alone, without proper motivation and supportive therapy, it is unlikely that it will have any substantive effect on the drinking pattern of the chronic alcoholic.

CONTRAINDICATIONS

Patients who are receiving or have recently received metronidazole, paraldehyde, alcohol, or alcohol-containing preparations, e.g., cough syrups, tonics and the like, should not be given disulfiram.

Disulfiram is contraindicated in the presence of severe myocardial disease or coronary occlusion, psychoses, and hypersensitivity to disulfiram or to other thiuram derivatives used in pesticides and rubber vulcanization.

WARNINGS

Disulfiram should never be administered to a patient when he is in a state of alcohol intoxication, or without his full knowledge.
The physician should instruct relatives accordingly.

The patient must be fully informed of the disulfiram-alcohol reaction. He must be strongly cautioned against surreptitious drinking while taking the drug, and he must be fully aware of the possible consequences. He should be warned to avoid alcohol in disguised forms, i.e., in sauces, vinegars, cough mixtures, and even in aftershave lotions and back rubs. He should also be warned that reactions may occur with alcohol up to 14 days after ingesting disulfiram.

The Disulfiram-Alcohol Reaction

Disulfiram plus alcohol, even small amounts, produce flushing, throbbing in head and neck, throbbing headache, respiratory difficulty, nausea, copious vomiting, sweating, thirst, chest pain, palpitation, dyspnea, hyperventilation, tachycardia, hypotension, syncope, marked uneasiness, weakness, vertigo, blurred vision, and confusion. In severe reactions there may be respiratory depression, cardiovascular collapse, arrhythmias, myocardial infarction, acute congestive heart failure, unconsciousness, convulsions, and death.

The intensity of the reaction varies with each individual, but is generally proportional to the amounts of disulfiram and alcohol ingested. Mild reactions may occur in the sensitive individual when the blood alcohol concentration is increased to as little as 5 to 10 mg per 100 mL. Symptoms are fully developed at 50 mg per 100 mL, and unconsciousness usually results when the blood alcohol level reaches 125 to 150 mg.

The duration of the reaction varies from 30 to 60 minutes, to several hours in the more severe cases, or as long as there is alcohol in the blood.

Concomitant Conditions

Because of the possibility of an accidental disulfiram-alcohol reaction, disulfiram should be used with extreme caution in patients with any of the following conditions: diabetes mellitus, hypothyroidism, epilepsy, cerebral damage, chronic and acute nephritis, hepatic cirrhosis or insufficiency.

PRECAUTIONS

Patients with a history of rubber contact dermatitis should be evaluated for hypersensitivity to thiuram derivatives before receiving disulfiram (see CONTRAINDICATIONS).

It is suggested that every patient under treatment carry an Identification Card stating that he is receiving disulfiram and describing the symptoms most likely to occur as a result of the disulfiram-alcohol reaction. In addition, this card should indicate the physician or institution to be contacted in an emergency. (Cards may be obtained from QUALITEST PHARMACEUTICALS upon request.)

Alcoholism may accompany or be followed by dependence on narcotics or sedatives. Barbiturates and disulfiram have been administered concurrently without untoward effects; the possibility of initiating a new abuse should be considered.

Hepatic toxicity including hepatic failure resulting in transplantation or death have been reported. Severe and sometimes fatal hepatitis associated with disulfiram therapy may develop even after many months of therapy. Hepatic toxicity has occurred in patients with or without prior history of abnormal liver function. Patients should be advised to immediately notify their physician of any early symptoms of hepatitis, such as fatigue, weakness, malaise, anorexia, nausea, vomiting, jaundice, or dark urine.

Baseline and follow-up liver function tests (10 to 14 days) are suggested to detect any hepatic dysfunction that may result with disulfiram therapy. In addition, a complete blood count and serum chemistries, including liver function tests, should be monitored.

Patients taking disulfiram tablets should not be exposed to ethylene dibromide or its vapors. This precaution is based on preliminary results of animal research currently in progress that suggest a toxic interaction between inhaled ethylene dibromide and ingested disulfiram resulting in a higher incidence of tumors and mortality in rats. A correlation between this finding and humans, however, has not been demonstrated.

Drug Interactions

Disulfiram appears to decrease the rate at which certain drugs are metabolized and therefore may increase the blood levels and the possibility of clinical toxicity of drugs given concomitantly.

DISULFIRAM SHOULD BE USED WITH CAUTION IN THOSE PATIENTS RECEIVING PHENYTOIN AND ITS CONGENERS, SINCE THE CONCOMITANT ADMINISTRATION OF THESE TWO DRUGS CAN LEAD TO PHENYTOIN INTOXICATION. PRIOR TO ADMINISTERING DISULFIRAM TO A PATIENT ON PHENYTOIN THERAPY, A BASELINE PHENYTOIN SERUM LEVEL SHOULD BE OBTAINED. SUBSEQUENT TO INITIATION OF DISULFIRAM THERAPY, SERUM LEVELS OF PHENYTOIN SHOULD BE DETERMINED ON DIFFERENT DAYS FOR EVIDENCE OF AN INCREASE OR FOR A CONTINUING RISE IN LEVELS. INCREASED PHENYTOIN LEVELS SHOULD BE TREATED WITH APPROPRIATE DOSAGE ADJUSTMENT.

It may be necessary to adjust the dosage of oral anticoagulants upon beginning or stopping disulfiram, since disulfiram may prolong prothrombin time.

Patients taking isoniazid when disulfiram is given should be observed for the appearance of unsteady gait or marked changes in mental status, the disulfiram should be discontinued if such signs appear.

In rats, simultaneous ingestion of disulfiram and nitrite in the diet for 78 weeks has been reported to cause tumors, and it has been suggested that disulfiram may react with nitrites in the rat stomach to form a nitrosamine, which is tumorigenic. Disulfiram alone in the rat’s diet did not lead to such tumors. The relevance of this finding to humans is not known at this time.

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