Module 3.1.1 (Drugs for Treatment of Alcohol Abuse) Flashcards

1
Q

What are psychomotor depressants?

A

Benzodiazepines Barbiturates Opiates Alcohol GHB

  • Administration results in sedation, reduced sensory and motor function, reduced anxiety and euphoria
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2
Q

Why are barbiturates not used as anxiolytics and hypnotics anymore?

A

Barbiturate overdoses are often fatal due to deep coma & respiratory arrest

  • Barbiturates are now obsolete since they readily lead to psychological & physical dependence and small overdose can be fatal.
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3
Q

What is the MOA of barbiturates?

A
  • Increase the duration of the GABA-gated chloride channel openings
  • At high concentrations are GABA- mimetic by directly opening the chloride channels and they may also produce other inhibitory effects such as depression of excitatory neurotransmitter actions
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4
Q

What are examples of barbiturates? What do they do? Side effects?

A

E.g. Phenobarbitone, primidone, amylobarbital

  • Enhances inhibition at synapses where GABA acts on GABAA receptors
  • Abuse potential due to euphoric effects
  • High risk of dependence
  • Toxicity symptoms include nystagmus, ataxia, drowsiness, coma, respiratory depression, hypothermia, acute renal failure
  • Should NOT be ceased abruptly
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5
Q

For GHB (gamma hydroxybutyrate):

A) What is it also known as

B) What are the 2 binding sites

A

A)

  • Also known as liquid ecstasy, fantasy, juice or G
  • Date rape drug ™
  • Liquid, capsules or crystals
  • Taken orally or injected

B)

  • 2 distinct binding sites
  • GHB receptor → excitatory
  • GABAB receptor → inhibitory

> GHB exists endogenously at concentrations to activate GHB receptor but not the GABAB receptor

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6
Q

What are some properties of heroin - diacetylmorphine (opioids)?

A

Heroin more lipid soluble than morphine hence enters CNS more rapidly

  • Significantly reduced by first pass metabolism by liver, hence injection and inhalation are preferred means of administration by illicit drug users
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7
Q

How is ethanol absorbed in the body and what is absorption rate increased by?

A

Mainly absorbed from small intestine and diffuses into nearly all tissues

Absorption rate increased by:

  • rapid gastric emptying
  • absence of fat, protein and carbohydrates

> 80% metabolized by liver to acetaldehyde

> 12% in stomach

> 5% excreted unchanged from lungs, sweat and urine

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8
Q

What is the MOA of ethanol?

A

Alcohol activates GABA receptors to cause sedation (in a similar way to BZD, barbiturates & GHB)

  • Potent inhibitor of glutamate receptors
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9
Q

Explain the following that occurs with repeated exposure of ethanol:

A) Cellular or pharmacodynamic tolerance

B) Metabolic or pharmacokinetic tolerance

C) Physical addiction

D) Behavioural tolerance

A

A)

  • Cell membrane alteration and complex neurochemical changes occur

B)

  • After 1‐2 weeks drinking, daily rate of ethanol metabolism by liver increase 30%

C)

  • Once cells have adapted, structural and biochemical changes may not return to original state for few weeks

D)

  • Adaptation behaviour so one function better at the same blood alcohol concentration
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10
Q

What are the pharmacological efffects of ethanol in CNS?

A

depressant effects

  • enhancement of both GABA‐ and glycine‐mediated inhibition
  • inhibition of Ca2+ entry through voltage‐gated calcium channels –> reduce excitatory neurotransmitter release
  • activation of certain types of K+ channel
  • inhibition of ionotropic glutamate receptor function = CNS depressant effects
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11
Q

What are the behavioural effects of ethanol?

A

Slurring of speech, sedation ™

Impairment of intellectual

Impairment of motor function, staggering gait ™

Increased self‐confidence, euphoria, mood changes ™

Psychiatric symptoms with heavy drinkers ™

Loss of consciousness at high doses ™

Blackouts: episodes of forgetting all or part of what happened whilst drinking

Fragmented sleep

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12
Q

What are the adverse effects of ethanol?

A

Neurotoxicity

  • Brain damage = irreversible

Effects on liver

  • Liver damage
  • Fatty liver

Effects on fetal development

  • Fetal alcohol syndrome
  • Alcohol related neurodevelopmental disorder (ARND)

Other effects –> thiamine deficiency

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13
Q

What are some withdrawal symptoms of ethanol? When does it begin and when is peak intensity?

A

Hand tremor, insomnia, difficulty in sleeping, feelings of generalized anxiety or panic attacks, autonomic system dysfunction including increased pulse, respiratory rate and body temperature, GI upset.

  • Begins within 5 to 10 days of decreasing alcohol intake
  • Peak intensity at day 2 or 3, usually improve by day 4 or 5

> Anxiety, insomnia and mild levels of autonomic dysfunction can persist for 6 months or more

> Seizures in small percentage of patients.

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14
Q

Explain how the following drugs treat alcoholism

A) BZD

B) Disulfiram

C) Naltrexone

D) Acamprosate

A

A)

  • Alleviate the acute abstinence syndrome during ‘drying out’

B)

  • To render alcohol consumption unpleasant

C)

  • To reduce alcohol‐induced reward

D)

  • To reduce craving
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15
Q

How does disulfiram work? What are the unpleasant symptoms associated with it? what benefits from it?

A

Blocks metabolism of alcohol –> inhibits aldehyde dehydrogenase –> blocks alcohol metabolism

  • Concurrent alcohol intake results in raised blood acetaldehyde concentrations – unpleasant symptoms –> nausea, profuse vomiting, flushing, sweating, palpitations, tachycardia, dyspnoea, hyperventilation, headache

> encourages abstinence from ethanol use

> Severe reactions can cause cardiotoxicity, convulsions or loss of consciousness

> Only suitable for highly compliant motivated patients who understand the risk. Should be alcohol free for previous 24 hours

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16
Q

How does acamprosate work? When to start?

A

Decreases symptoms of alcohol withdrawal (anxiety, insomnia, craving)

  • Used as adjunct to social and psychological treatment
  • Similar chemical structure to GABA and may work by stimulating inhibitory neurotransmission

> Start one week after ceasing alcohol consumption

17
Q

How does naltrexone work?

A
  • Opioid antagonist –> prevents euphoria associated with opioid abuse
  • Blocks effects of endogenous opioids released following alcohol consumption
  • Used in combination to social and psychological treatment