Substance misuse

Question 1

what is reinforcement and when is this likely to occur?

Answer 1

this is the addictive potential of a drug
drugs which act more rapidly are used more frequently and are subsequently more addictive, so a shorter half life drug e.g. lorazepam, is taken more often so is more reinforcing.

Question 2

why is methadone less reinforcing?

Answer 2

longer t1/2 so taken less frequently

Question 3

1st signs of opioid withdrawal?

Answer 3

sweating
akathisia
lacrimating
goosebumps
yawning

Question 4

usual starting dose of methadone?

Answer 4

30mg

Question 5

when would starting dose of methadone be lower?

Answer 5

anorexic patients

COPD patients

Question 6

what is the dosing regimen for detoxification with methadone?

Answer 6

once stable on dose (usually around 60mg), can be reduced at a rate that will result in 0 in around 12 wks. usually reduction of 5mg every 1 or 2 weeks.

Question 7

how is it decided whether methadone or buprenorphine should be used for opioid detoxification?

Answer 7

start with same medication as used for any maintenance treatment/what the patient has stabilised with.
consider preference of service user.
pts report being able to reduce buprenorphine doses more quickly than methadone.

Question 8

length of time for opioid detoxification?

Answer 8

4 weeks inpatient

up to 12 weeks outpatient

Question 9

when might lofexidine be considered in opioid withdrawal?

Answer 9

this is a non-opioid alpha-adrenergic agonist and is not a controlled drug
may be considered in those who have decided not to use methadone or buprenorphine, those who have decided to detoxify within a short time period or have mild or uncertain dependence, including young people.

Question 10

disadvantages of lofexidine in opioid withdrawal?

Answer 10

additional ST meds may be needed to control other effects of opioid withdrawal e.g. stomach cramps-mebeverine and diarrhoea-loperamide.
pt should be advised to take part of dose at bedtime to offset insomnia assoc with opioid WD.

Question 11

side effects of methadone WD?

Answer 11

myalgia

Question 12

why are patients at increased risk of OD on illicit drugs following opioid withdrawal?

Answer 12

lose opioid tolerance so will take more of the drug to have the same therapeutic effect as before, so increased risk of OD and death, that may be potentiated by use of alcohol or BZDs.

Question 13

what are the indications for service users to NOT have detoxification in a community setting, but as an inpatient?

Answer 13

previously not benefited from formal community based detoxification
need medical and nursing care as significant co-morbid physical or mental health problems
require complex polydrug detox, e.g. concurrent detox from alcohol or BZDs
are experiencing significant social problems that will limit benefit of community based detox.

Question 14

what drug may be helpful following opioid detox to maintain abstinence?

Answer 14

naltrexone=opioid antagonist
blocks former opiate user from experiencing effects of opiates
LFTs to be done before and during tmetn as potentially hepatotoxic
usual 50mg maintenance

Question 15

general measures in stimulant withdrawal e.g. cocaine?

Answer 15

giving preventive advice about safer injecting practice
treat psychiatric problems on a symptomatic basis
abstinence-based psychosocial tment linking counselling and social support has been shown to have greatest impact on cocaine misuse
focus on stress reduction procedures if pt exhibits persistent anxiety and agitation
if persistent and severe psychotic symptoms, may need psychiatric unit admission
monitor pt’s mood and assess risk of suicide as stimulant WD can be assoc with significant depression
substitute stimulant prescribing does not have demonstrated effectiveness, but there is evidence that if maintenance tments of methadone or buprenorphine prescribed to those with opioid dependence who also take cocaine, their cocaine use can be expected to decrease or stop and when persists, may respond positively to improvement of opioid maintenance tment.

Question 16

use of antidepressants in pts who misuse stimulants?

Answer 16

antidepressants such as the SSRI fluoxetine can be effective in management of major depressive episodes assoc. with stimulant use
BUT care must be taken if SSRIs given while using cocaine or amphetamines as toxic reactions have been described.

Question 17

how does LSD in terms of dosage differ from other drugs?

Answer 17

only micrograms required to be effective, compared to milligrams for other drugs.

Question 18

3 prominent effects cocaine has on the body?

Answer 18

powerful local anaesthetic
powerful vasoconstrictor
powerful psychostimulant that has stong re-inforcing qualities

Question 19

major mortality risk with cocaine use?

Answer 19

MIs and CVAs as poweful vasoconstrictor causing rapid increase in BP and heart strain

Question 20

how is crack cocaine taken?

Answer 20

smoked-effects produced most quickly-greater experience of euphoria so reinforcement and possibility of side effects greater.
effects in 6-8s

Question 21

effects of cocaine on peripheral organs?

Answer 21

increased HR and vasconstriction, causing BP increase
increased muscular activity and vasconstriction causing increased body temp.
dilation of pupils
tremor
sweating

Question 22

CNS effects of cocaine?

Answer 22

euphoria, excitement, restlessness, decreased appetite

Question 23

cocaine MOA?

Answer 23

inhibits reuptake of dopamine, NA and 5-HT in synapse, potentiating their actions.
increase in dopamine causes euphoria

Question 24

why does tolerance occur with cocaine?

Answer 24

chronic exposure of post-synaptic receptors to dopamine causes a decrease in the number of post synaptic receptors (downregulation) and an increase in presynaptic dopamine transporter protein, so reduced sensitivity of postsynaptic receptors to dopamine and increased sequestration by presynaptic neurones.

Question 25

MOA of amphetamines (whiz, speed, uppers)?

Answer 25

synthetic chemicals which structurally resemble dopamine, 5-HT and NA.
can displace dopamine from storage vesicles so dopamine diffuses into synaptic cleft
euphoria and arousal produced via dopamine effect
decreased appetite likely due to NA effect

Question 26

behavioural effects of amphetamines?

Answer 26

stereotyped behaviour

thought to be due to effects of dopamine in the nigrostriatal system

Question 27

what is methamphetamine?

Answer 27

Ice/crystal/crank/meth
more pronounced stimulatory CNS effects than amphetamine, and less peripheral actions
high doses can produce psychotic reactions characterised by hallucinations, paranoia and mania.

Question 28

examples of psychostimulants?

Answer 28

cocaine
amphetamines
caffeine
nicotine

Question 29

mainstay of tment to eliminate symptoms of WD from stimulants?

Answer 29

psychosocial interventions

Question 30

Features of wernicke’s encephalopathy?

Answer 30

truncal ataxia-wide based gait
ophthalmoplegia-nystagmus, lateral rectus or conjugate gaze palsies
mental confusion

Question 31

Pathophysiology of wernicke’s encephalopathy?

Answer 31

Thiamine deficiency due to alcoholism or poor diet results in midbrain haemorrhages which produces an acute syndrome requiring tment with parenteral thiamine (pabrinex) to stop the bleeding.
Repeat haemorrhages occur (multiple wernicke’s episodes) produces korsakoff syndrome characterised by amnesia and confabulation- patients will tell you an elaborate story and then after 40 mins or so will give a completely different answer to the same qn asked as they can’t remember what they prev said.

Question 32

How does alcohol cause thiamine deficiency?

Answer 32

Destroys small bowel uptake pump

May be assoc with poor diet so pt takes in less thiamine.

Question 33

Why can buprenorphine only be given to combat WD from opioids in those who are already in mild withdrawal?

Answer 33

It is a partial agonist so produces only half a response

Question 34

Safety of buprenorphine in opioid WD?

Answer 34

Unable to OD on buprenorphine alone, partial agonist

Methadone-synthetic mu agonist

Question 35

Biochemical response in opioid withdrawal?

Answer 35

Profound dopamine decrease in nucleus accumbens and reduction in dynophin
Large increase in release of noradrenaline in hippocampus, nucleus accumbens and locus coeruleus

Question 36

How is alcohol thought to have an amnesic effect?

Answer 36

Inhibits ACh release in the CNS

Question 37

How is alcohol thought to have a positive reinforcing effect?

Answer 37

By binding to GABA A receptor, it results in inhibition of inhibitory interneurones, mediating excitatory effects on dopamine neurones in the VTA.
May also act directly on dopamine neurones.

Question 38

How is alcohol tolerance mediated?

Answer 38

Liver increases its amount of metabolising enzyme (25%of tolerance.)
Tissue of functional tolerance where neurones in brain adapt to amount of drug present.

Question 39

If detoxing from alcohol but pt has liver failure, which BZD should be used?

Answer 39

Oxazepam as least liver toxic.

Question 40

Symptoms of alcohol withdrawal?

Answer 40

Sweating
Tremor
Tachycardia
Anxiety
Visual hallucinations
Increase BP
Delirium tremens-requires BZD tment.

Question 41

Interventions for mild alcohol dependence?

Answer 41

Offer a psychological intervention e.g. CBT, behavioural therapy or social network and environment based therapies
Behavioural couples therapy if regular partner who is willing to engage
If unsuccessful or if asked for, consider pharmacological therapy with acamprosate or oral naltrexone alongside psychological intervention
For assisted WD, offer BZD chlordiazepoxide or diazepam. Gradually reduces dose over 7 to 10 days to prevent alcohol withdrawal from recurring. Give higher doses if severe alcohol dependence.

Question 42

Management of moderate to severe alcohol dependence after WD?

Answer 42

So WD with high dose of chlordiazepoxide or diazepam, reduced gradually over 7 to 10 days.
Then offer acamprosate or oral naltrexone with an individual psychological intervention e.g. CBT
Offer disulfiram for abstinence if acamprosate and naltrexone unsuitable or patient would prefer this.

Question 43

Considerations given to wernicke-korsakoff encephalopathy in alcohol WD?

Answer 43

In planned assisted WD give parenteral thiamine followed by oral thiamine to reduce risk of encephalopathy if in special inpatient alcohol services or prison and malnourished or at risk of malnourishment or have decompensated liver failure.

Question 44

what is delirium tremens and how is it treated?

Answer 44

medical emergency in which a hyperadrenergic state is present
due to alcohol WD state where loss of GABA A receptor stimulation causes a reduction in chloride flux and is assoc with tremors, excessive sweating, tachycardia, anxiety and seizures. lack of glutamate NMDA receptor inhibition may cause seizures and delirium.
characterising features=altered mental status=confusion, delusion, severe agitation, hallucinations-auditory, visual-lilliputian or olfactory
usually begins 1-3 days post stopping alcohol

A to E approach to patient
sedate patients with BZDs e.g. diazepam-rapid action onset, addition of barbiturates may also be necessary in those refractory to BZD treatment and may reduce the need for mechanical ventilation in very unwell patients in ITU.
if also wernicke’s encephalopathy, need IV pabrinex (500mg thiamine) at least 2 pairs of ampolues TDS for 3 days, if response then continue with two ampoules of Pabrinex® once daily for five days or for as long as improvement continues.
Magnesium may also protect against seizures and arrhythmias.

Question 45

RFs for delirium tremens?

Answer 45

prev. delirium tremens
prev. hx of alcohol withdrawal seizures
older age
more severe WD symptoms of presentation
abnormal liver function
recent higher than normal levels of alcohol intake
co-existing infection or medical problems including hepatitis and pancreatitis