Psych - Substance Misuse

Question 1

Alcohol: how do you calculate units?

Answer 1

Need: alcohol % and volume in L

• Eg 500ml bottle of 35% vodka
• 0.5L x 35 = 17.5 units of alcohol

Question 2

Alcohol misuse: what is thiamine deficiency? Name some features and causes

Answer 2

• Early features: non-specfic, poor memory problems, irritability and sleep disturbance
• Causes of deficiency
  
  • Poor diet
  • Alcohol destroys the thiamine transporter in the gut
• Importance of thiamine: maintains cell health - esp in the brain

Question 3

Alcohol misuse: what is Wernicke’s encephalopathy?

Answer 3

• Acute syndrome when patient gets acute low thiamine - patient gets haemorrhages in mid-brain (irreversible)
• Symptoms: ataxia, nystagmus, nerve palsies (3,4 and 6th)
• Other sx; vomiting, decreased consciousness, fever/hypothermia, ptosis and abnormal pupillary reflexes
• Treatment: parenteral thiamine (pabrinex IM)

Question 4

Alcohol misuse: what is Korsakoff’s?

Answer 4

• Results from repeated episodes of Wernicke’s
• Prominent impairment of recent and remote memory, but immediate recall is usually preserved
• Disordering of time and events (can’t learn new things) and confabulation can be present
• Irreversible

Question 5

Alcohol misuse: treatment options

Answer 5

• Diazepam: has long T1/2, which helps with reinforcement and smoothes wirthdrawal (max 4 weeks)
• Relapse prevention: disulfaram - blocks aldehyde dehydrogenase pathway (increasing acetaldehyce accumulation) - get absolutely terrible hangovers

Question 6

Alcohol misuse: mechanism of withdrawal

Answer 6

• Chronic alcohol consumption enhances GABA mediated inhibition in CNS (similar MOA to benzos) and inhibits NMDA type glutamate receptors
• Alcohol withdrawal is thought to lead to the opposide - decreased inhibitory GABA and increased NMDA glutamate transmission

Question 7

Alcohol misuse: features of withdrawal

Answer 7

• 6-12h: sx begin - tremor, sweating, tachycardia, anxiety
• 36h: peak incidence of seizures
• 48072h: peal incidence of delirium tremens - coarse tremor, confusion, delusions, auditory and visual hallucinations, fever, tachycardia

Question 8

Alcohol misuse: management of acute withdrawal

Answer 8

• Should admit patient to hospital for monitoring until stable
• 1st line: benzos (chlordiazepoxide) - giveb as part of a reducing dose protocol or PRN (hospital dependent)
• Carbamazepine may be used

Question 9

Opiate addiction: treatment

Answer 9

• Methadone: long T1/2 (>24h), synthetic opiate which is given as a single daily dose
• Buprenorphine: partial agonist (v difficult to OD on it alone) but provides increased cognitive awareness, which can be difficult for people using drugs to drown things out
• Relapse prevention: Naltrexone - opiate blocker taken orally that will block the effect of heroid