Medical Pharmacology

at a Glance

Michael J. Neal

Case Studies

Case 11: Alcohol dependence

A 60-year-old man was brought to A&E unconscious and smelling of alcohol. Examination did not reveal any head injury and blood glucose was in the normal range. The next morning he was awake and admitted to drinking a bottle of whisky daily in addition to cider and other drinks.

  • (a) What would be the main risk in withdrawing alcohol from this patient? How would you alleviate this risk?

    Correct answer:

    Withdrawal of alcohol from this patient is likely to precipitate epileptic seizures. Withdrawal of alcohol requires the administration of a long-acting benzodiazepine, usually chordiazepoxide. This is given for up to 2 weeks in gradually decreasing doses. Administration for a longer period risks the development of dependence on the benzodiazepine. Clomethiazole is an alternative central nervous system depressant but is more likely to produce dependence.

  • (b) What vitamin deficiency might this patient have?

    Correct answer:

    Alcohol inhibits the uptake of thiamine (vitamin B1) from the gastrointestinal tract and alcoholics often become thiamine deficient. Since this deficiency can lead to neuronal damage (Chapter 21) it is usual to administer thiamine.

  • (c) What drugs can be helpful in maintaining abstinence in patients dependent on alcohol?

    Correct answer:

    Abstinence in non-drinking alcoholics can be helped by daily acamprosate. When accompanied by counselling and support, the drug increases the chance of complete abstinence. The mechanism of acamprosate is uncertain. Its structure bears some similarities to both glutamate and GABA. It may reduce the action of excitatory amino acid transmitters and/or enhance the actions of GABA. Disulfiram inhibits the enzyme aldehyde dehydrogenase causing acetaldehyde to accumulate. This toxic metabolite of alcohol induces a very unpleasant reaction (e.g. vasodilatation, sweating, nausea and vomiting) and deters the patient from taking alcohol. It requires a well-motivated patient as it is essential for the drug to be taken daily.

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