Drugs of Abuse

Question 1

Classes of drugs of abuse with examples

Answer 1

1. Stimulants - amphetamines, cocaine, piperazines (BZP), cathinones
2. Sedatives/dissociatives - alcohol, opiates, GHB/GBL, ketamine
3. Hallucinogens - Magic mushrooms, LSD, phenylethylamines, synthetic tryptamines
4. Cannabinoids

Question 2

Types of cocaine

Answer 2

1. cocaine hydrochloride - coke (snort)

2. Cocaine base - crystals - crack (smoke)

Question 3

Cathinones

Answer 3

khat plant - chewed for its amphetamine-like stimulant properties, used by indigenous people in East Africa

Question 4

Synthetic cathinones

Answer 4

Mephedrone (mcat/meow meow). Active ingredient is cathinone. Very similar structure to neurotransmitters - mess with brain

Question 5

Effects of stimulants

Answer 5

• increased alertness, confidence and euphoria
• Sympathomimetic effects - dilated pupils, tachycardia, hypertension
• tremor. hypertonia, hyper-reflexia, convulsions

Question 6

Life threatening effects of stimulants

Answer 6

• hallucinations
• rhabdomyolysis
• hyperthermia
• cardiac arrhythmias and myopathy
• intracerebral and subarachnoid haemorrhage
• acute renal failure
• fulminant hepatic failure

Question 7

Management of patient on stimulants

Answer 7

1. reassurance and supportive measures
2. Diazepam 10mg IV, repeated as necessary
3. For hyperthermia: active cooling and possible dantrolene (reduces skeletal muscle contraction)

Question 8

Ingestion, absorption, metabolism and action of heroin

Answer 8

HEROIN IS A PRO-DRUG

1. injected/snorted/smoked to prevent 1st pass metabolism
2. rapidly passes through BBB (acetyl groups increase lipid solubility)
3. Deacetylation in CNS –> 6MAM –> morphine
4. Morphine is mu opioid receptor agonist - causes analgesia and euphoria via dopaminergic pathways

Question 9

How can we test for heroin

Answer 9

look for presence of 6MAM in urine

Question 10

Why can’t morphine be used as a test for heroin?

Answer 10

codeine is also converted to morphine in the body

Question 11

Effects of opiates (e.g. heroin)

Answer 11

• analgesia and euphoria
• sedation, suppression of cough reflex, miosis, constipation
• rarely: pulmonary oedema, cardiac conduction abnormalities

Question 12

Effects of opiate overdose

Answer 12

Excessive mu receptor stimulation –>

• coma
• RESPIRATORY ACIDOSIS (respiratory depression, low pO2, high pCO2)

Question 13

Management of heroin poisoning

Answer 13

1. ABC

2. Naloxone (opiate receptor competitive antagonist) - IV or IM - short half life so repeated doses required

Question 14

Methadone

Answer 14

Synthetic opioid used as a heroin substitute with long half life (20-50hours) to mitigate withdrawal symptoms. Dose gradually reduced to 0. Just as addictive as heroin.

Question 15

Examples of phenylethylamines (hallucinogens)

Answer 15

NBOMe agents - potent serotonergic effects (high affinity for serotonin 2a receptor)
Benzofurans: serotonin-noradrenaline-dopamine reuptake inhibitors

Question 16

Effects of phenylethylamines

Answer 16

tachycardia, hypertension, agitation, visual and auditory hallucinations, seizures and rhabdomyolysis

Question 17

Synthetic Cannabinoids

Answer 17

Slightly tweaked structure of tetrahydrocannabinol. Highly potent - full agonists at the cannabinoid receptors CB1 and CB2. Clear liquid sprayed onto smokeable plant material

Question 18

Effects of synthetic cannabinoids

Answer 18

• nausea and vomiting, sinus tachycardia, coma
• acute respiratory failure, dilated pupils
• agitation/paranoia, seizures
• rarely: MI, stroke, AKI