alcohol abuse

Question 1

How do you understand alcohol labelling?

Answer 1

%ABV = alcohol by volume eg. 12% ABV means 12 units per litre (therefore in a 12% 75cl bottle of wine there would be 9 units - 12x0.75)

1 unit = 10ml ethanol = 8g ethanol

forensic measures = %ABV x 0.78 = g/100ml

Question 2

how is alcohol absorbed?

Answer 2

simple diffusion
over 80% occurs in the duodenum-jejunum
rate of absorption is concentration dependant and related to stomach emptying

Question 3

how is alcohol distributed?

Answer 3

rapidly distributed
crossed blood-brain barrier easily
roughly equal to total body water
fatter people have a higher relative blood concentration (see notes for image explaining)

Question 4

how is alcohol metabolised?

Answer 4

98% is metabolised as below:
(see notes for a better image)
- ethanol is metabolised to acetaldehyde by alcohol dehydrogenase (ADH) - this is the rate limiting step
- acetaldehyde is metabolised to acetate by acetaldehyde dehydrogenase (ALDH)
- this gives of C02 and H20

Question 5

how is alcohol eliminated?

Answer 5

clearance rate of 6g/ hour or maybe slightly higher. often 1 unit per hour is used as an estimation

small amounts are not metabolised and are excreted unchanged in urine and breath - this is a useful detection tool

Question 6

how is alcohol eliminated?

Answer 6

clearance rate of 6g/ hour or maybe slightly higher. often 1 unit per hour is used as an estimation

small amounts are not metabolised and are excreted unchanged in urine and breath - this is a useful detection tool

Question 7

what are the legal driving limits for alcohol?

Answer 7

80mg/ 100ml blood
35 micrograms / 100ml breath
107 mg / 100ml urine

Question 8

what are the pharmacological effects of alcohol?

Answer 8

GABA-A potentiation - this is a major inhibitory neurotransmitter

NMDA antagonist - causes glutamate inhibition (major excitatory neurotransmitter)

effects on serotonin, opioid and dopaminergic neurotransmission (reward centres)

(see image in notes of the effect different levels of alcohol can have on you)

Question 9

what drugs can alcohol interact with?

Answer 9

CNS drugs - increase drowsiness/ sedation eg. phenothiazines, tricyclic antidepressants, antihistamines, benzodiazepines

Antihypertensive / CV drugs - enhanced hypotensive effect

Warfarin - major changes in consumption of alcohol may affect anticoagulant control

Metronidazole / ketoconazole - inhibit aldehyde dehydrogenase causing a disulfiram like reaction (inhibits ALDH)

Question 10

how may alcohol be used medically?

Answer 10

locally in bactericidal swabs and gels
in pharmaceutical solutions
methanol / Ethelene glycol poisoning - competitively inhibits ADH
in withdrawal

Question 11

what problems are associated with alcohol? (medical and psychiatric)

Answer 11

acute alcohol intoxication
alcohol withdrawal reactions
chronic alcoholism
contributes to many conditions including the obesity epidemic

Question 12

what must you ask when taking a history about alcohol?

Answer 12

use of an alcohol diary may be helpful

differentiate between binging and regular use

ask about amount of weekly income spent on alcohol - this is normally a good gage of dependence

CAGE 2 questionnaire - 2 positive answers (high sensitivity and specificity)

• Cut down - have you ever tried to cut down how much you drink?
• annoyed - have you ever been annoyed by someone’s criticism over how much you drink?
• guilty - have you ever felt guilty about how much you drink?
• eye opener - have you ever needed alcohol in the morning?

Question 13

what should you look for in an examination in a patient with a history of alcohol use?

Answer 13

usually no specific findings 
signs of chronic liver disease 
parotid enlargement 
peripheral neuropathy 
signs of withdrawal

Question 14

what laboratory tests may you do in a patient with a history of alcohol use and what might they show?

Answer 14

FBC - macrocytosis 
U&Es - low urea 
LFTs - raised transaminases 
Gamma GT - elevated 
INR - prolonged PT

Question 15

outline the withdrawal symptoms of alcohol

Answer 15

6-12 hours

• insomnia
• tremulousness
• anxiety
• GI upset
• diaphoresis
• palpitations
• anorexia

12-24 hours
- alcoholic hallucinosis - visual, auditory or tactile hallucinations

24-46 hours
- withdrawal seizures - generalised tonic-clonic seizures

48-72 hours
- delirium tremens - hallucinations, disorientation, tachycardia, raised BP, mild fever, agitation, diaphoreis

often a patient who is hospital for another reason, and you are unaware has an alcohol problem, may present with withdrawal symptoms as there is no alcohol available in hospital.

Question 16

outline the management for a patient who has presented with alcohol overdose

Answer 16

as always, start with ABC resuscitation

prevention/ treatment of encephalopathy - patients with alcohol dependence are at high risk of developing Wernicke’s encephalopathy. (eye signs, ataxia and confusion). This is treated with high dose thiamine and other B vitamins.

prevention/ treatment of withdrawal

• benzodiazepines are prescribed to treat withdrawal symptoms
• for delirium tremens the benzodiazepine lorazepam is specifically used

prevention/ treatment of complications

• psychosocial rehabilitation
• pharmacological maintenance of abstinence

Question 17

what drugs can be used as pharmacological maintenance of abstinence and how do they work?

Answer 17

acamprosate - stabilises glutamate and GABA systems which reduces cravings, anxiety and insomnia

naltrexone - opioid antagonist which is helpful as an adjunct to alcohol dependence after withdrawal is treated to reduce the rate of relapse

nalmafene - opioid receptor modulator - reduction of alcohol consumption if taken 1-2 hours before drinking

disulfiram - inhibits intermediate metabolism of alcohol leading to flushing, sweating and nausea