Download Part 1 Alcohol and Medication

Medicines Optimisation briefing
11/001
Increasing the Awareness of Medicines Interactions - Alcohol and Medication
This is the first in a series of safety briefings that focus on how alcohol, food, caffeine, street drugs and
smoking can all influence the safety and efficacy of a medicine. The aim of these briefings is to increase
awareness so that Trust staff recognise when an individual’s recovery is potentially compromised by an
interaction between their lifestyle choices and their prescribed medication. This briefing covers the risks
of alcohol consumption for people taking prescribed medication.
It is essential to carry out a full physical assessment, including an assessment of liver function, for all
individuals who are known to consume alcohol regularly prior to prescribing medication. The British
National Formulary (BNF) and Summary of Product Characteristics (www.medicines.org.uk) provide
guidance on the suitability of individual medications in hepatic impairment.
Even with normal hepatic function, there is the potential for complex interactions between alcohol and
medication via other mechanisms. These mechanisms are discussed below with examples of
medications that are affected in this way.
1) Pharmacodynamic Interactions
Alcohol enhances the inhibitory effects of gamma-aminobutyric acid (GABA), reduces the excitatory
effects of glutamate and increases dopamine release. Alcohol therefore causes enhanced CNS
depression (drowsiness, amnesia, ataxia), respiratory depression, hypotension and a worsening of
psychotic symptoms in vulnerable people. An increase in blood pressure and dehydration resulting in
cardiac problems can also occur. If these effects are mirrored by the actions/side effects of
prescribed medication then the effects can be additive and hazardous.
Medication that can combine effects with alcohol in this way include ACE inhibitors (e.g. ramipril),
antihistamines, antipsychotics, baclofen, barbiturates, benzodiazepines, beta blockers, calcium
channel blockers (e.g. amlodipine), lofexidine, nitrates, opiates, tricyclic antidepressants and Zhypnotics.
Particularly hazardous medicine-alcohol combinations include barbiturates, benzodiazepines,
tricyclic antidepressants, monoamine oxidase inhibitors (MAOIs), lithium and propranolol.
N.B. Propranolol is not recommended in the latest NICE or Trust guidance for the treatment of
anxiety
and
its
use
with
alcohol
has
been
associated
with
deaths.
11/001 Increasing Awareness of Interactions - Alcohol and Medication
Issue Date: August 2016
Review Date: November 2017
Page 1 of 2
2) Pharmacokinetic Interactions
a) Induction of liver enzymes due to chronic alcohol consumption
Alcohol is metabolised in the body by alcohol dehydrogenase (ADH) and other enzymes in the
liver. Chronic consumption of alcohol causes an increase in these enzymes as the body attempts
to control the alcohol level. When someone is prescribed a medication that is also metabolised by
these enzymes, the blood level of the medication may be affected by alcohol consumption. The
effect is variable, especially with binge drinking. Enzyme competition during intoxication may lead
to increased medication levels, whereas raised background levels of the enzyme when sober may
lead to reduced medication levels. This can complicate treatment when trying to determine an
effective dose of prescribed medication for an individual.
Medication that can be affected in this way includes benzodiazepines, carbamazepine, clozapine,
donepezil, galantamine, mirtazapine, phenobarbitone, risperidone, tricyclic antidepressants,
valproate, venlafazine and the Z- hypnotics.
b) Inhibition of the liver enzymes by prescribed medication
Metabolism of alcohol is a two stage process. Firstly, ADH and the liver enzymes metabolise
alcohol to acetaldehyde. Secondly, the resulting acetaldehyde is metabolised to water and
carbon dioxide.
If the first stage is inhibited, the effect of the alcohol lasts longer (e.g. with aspirin or ranitidine)
and if the second stage is inhibited the unpleasant effects due to acetaldehyde are increased (i.e.
flushing, sickness, headache, tachycardia, hypotension).
This can happen with disulfiram, isosorbide dinitrate, metronidazole, and nitrofurantoin.
The medication lists above are not exhaustive so please check the Summary of Product Characteristics
for queries regarding individual medications if you suspect that the person you are prescribing for is likely
to consume alcohol alongside their medication.
Advice for people who use our services on specific medication is available from the choice and
medication website available via the Trust website (www.choiceandmedication.org.uk/devon) and is
included on the patient information leaflets provided with the medication. For more information please
contact your local Medicines Optimisation team representative.
11/001 Increasing Awareness of Interactions - Alcohol and Medication
Issue Date: August 2016
Review Date: November 2017
Page 2 of 2