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  » Alcoholism and treatment  »  Drug interactions
Numerous drug interactions between alcohol and other drugs have been described. They are listed in Table 4.4

Table 4.4: Interactions of ethyl alcohol with other drugs

- CNS depressants such as opioids, hypnotics, transquillizers, antihistaminics, reserpine, methyldopa and clonidine can cause severe CNS depression in the presence of alcohol.
- Vasodilators (hydralazine and nitroglycerine) can cause additive orthostatic hypotension. On the other hand, heavy consumption of alcohol is known to cause transient hypertension.
- Alcohol potentiates the adverse effects of aspirin (GL bleeding), sulfonylureas (hypoglycemia) and oral anticoagulants (bleeding).
- Isoniazid can cause hepatic toxicity in the chronic alcoholics because of increased conversion to a toxic metabolite.
- Chlorpropamide, metronidazole and its analogues, griseofulvin, tolbutamide, cephalosporins and phenylbutazone can cause a mild disulfiram - like reaction (see below) in alcohol users.

METHYL ALCOHOL (Methanol): This is generally used in a 5% concentration to denature ethyl alcohol. Its absorption and distribution are similar as ethyl alcohol; the rate of metabolism, however, is very slow. It is mainly oxidized to formaldehyde and subsequently to formic acid, which is toxic. The latter reaction is folate dependent and causes folate depletion.

Pharmacological actions: Initially these resemble those of ethyl alcohol and are due to CNS depression. Methyl alcohol poisoning usually results from ingestion of methylated spirit or adulterated wines. The symptoms are due to:
   - CNS depression.
   - Acidosis following the production of formic and other organic acids, with marked anionic gap.
   - Toxicity of metabolites (formaldehyde and formic acid) to the retinal cells.

The symptoms may be delayed, particularly if ethanol is also consumed simultaneously. Usually, headache, vertigo, nausea, severe abdominal pain, dyspnoea and motor restlessness occur. Blood pressure is usually not affected but bradycardia has a bad prognostic significance. Coma can develop very rapidly, followed by death. In a very serious patient, the respiration is slow, shallow and gasping in type. Death is usually preceded by blindness. However, total blindness could occur with as little as 15 ml. of methyl alcohol while ingestion of 30 ml. is fatal.
Many deaths have been reported following the ingestion of methylated spirit for alcoholic effects.
Treatment of toxicity: This is directed towards correcting the acidosis as quickly as possible. The development of blindness, though not due to acidosis, is enhanced by acidosis. It must be emphasized that methyl alcohol is oxidized slowly and hence, acidosis can recur even after adequate initial alkali administration. It is necessary, therefore, to have close observation of the patient for several days to prevent sudden relapse and death. Hypokalemia, if present, needs correction; so also the maintenance of adequate nutrition and water and electrolyte balance. The patient's eyes should be protected from strong light. See Table 4.5 for folinic acid.
The infusion of ethyl alcohol has been recommended on the basis that it slows down the oxidation of methyl alcohol by competing for the same metabolic pathway. Ethanol administration can be life saving it, for some reasons, alkali therapy is delayed.

Table 4.5 summarises the treatment of methanol poisoning.

Table 4.5: Treatment of methanol poisoning.

- Hospitalization, nursing care.
- Gastric lavage, activated charcoal.
- Ethyl alcohol IV: 0.6 g/kg loading dose, followed by 10 g/hour by infusion, in adults.
- Treatment of acidosis; of hypokalemia, if present.
- Maintenance of nutrition.
- Folinic acid 1 mg/kg (maximum 50 mg) IV together with folic acid 1 mg/kg IV, 4 hourly for 6 doses, to accelerate the metabolic degradation of formate.
- Use of 4-Methyl pyrazole.
- Hemodialysis in severe cases.

METHYL PYRAZOLE is a inhibitor of alcohol dehydrogenase and has been found useful in the treatment of poisoning with methyl alcohol and EG. It is administered in the dose of 100 mg diluted in 250 ml of isotonic saline and infused slowly over 45 minutes. The inhibitory effect on the drug is rapid and prolonged. It is well tolerated and causes hardly any toxicity. Methyl alcohol and EG are rapidly cleared by the kidneys if the renal function is normal. Its use appears to be more effective than the use of ethyl alcohol.

Important Links and Resources

For more information on alcohol abuse and alcoholism, contact the following organizations:

Al-Anon Family Group Headquarters, Inc.
1600 Corporate Landing Parkway
Virginia Beach, VA 23454-5617
Phone: (757) 563-1600; Fax: (757) 563-1655
Internet address:

Makes referrals to local Al-Anon groups, which are support groups for spouses and other significant adults in an alcoholic person's life. Also makes referrals to Alateen groups, which offer support to children of alcoholics. Free informational materials and locations of Al-Anon or Alateen meetings worldwide can be obtained by calling the toll-free number (888) 425-2666 from the United States or Canada, Monday through Friday, 8 a.m.-6 p.m. (e.s.t.).

Alcoholics Anonymous (AA) World Services, Inc.
475 Riverside Drive, 11th Floor
New York, NY 10115
Phone: (212) 870-3400; Fax: (212) 870-3003
Email: via AA's Web site
Internet address:

Makes referrals to local AA groups and provides informational materials on the AA program. Many cities and towns also have a local AA office listed in the telephone book. All communication should be directed to AA's mailing address: AA World Services, Inc., Grand Central Station, P.O. Box 459, New York, NY 10163.

National Council on Alcoholism and Drug Dependence, Inc. (NCADD)
20 Exchange Place, Suite 2902
New York, NY 10005
Phone: (212) 269-7797; Fax: (212) 269-7510
HOPE LINE: (800) NCA-CALL (24-hour Affiliate referral)
Internet address:

Offers educational materials and information on alcoholism. Provides phone numbers of local NCADD Affiliates (who can provide information on local treatment resources) via the above toll-free, 24-hour HOPE LINE.

National Institute on Alcohol Abuse and Alcoholism (NIAAA)
Scientific Communications Branch
6000 Executive Boulevard,Willco Building, Suite 409
Bethesda, MD 20892-7003
Phone: (301) 443-3860; Fax: (301) 480-1726
Internet address:

Makes available free informational materials on all aspects of alcoholism, including the effects of drinking during pregnancy, alcohol use and the elderly, and help for cutting down on drinking.