Drugs of abuse

Question 1

Nicotine

Answer 1

Stimulant
Activates nicotinic ACh receptors, causing increases central neurotransmission and peripheral adrenaline.
Acute effects: hyperstimulation, reduced fatigue, mental alertness
Higher or repeated dosing leads to sedative effects
Withdrawal: cravings, anxiety, depression, insomnia, restlessness, weight gain.

Question 2

Cocaine

Answer 2

Stimulant
Blocks DAT/SLC6A3 dopamine transporters, causing increased monoamine activity in the CNS and PNS.
Acute effects: hyperstimulation, reduced fatigue, mental alertness. Also causes vasoconstriction, dilated pupils, and increased temperature, heart rate, and blood pressure.
Binges can lead to paranoid psychosis, cardiovascular complications, appetite reduction and malnourishment
Withdrawal: dysphoria, depression, anxiety, pain and cravings

Question 3

Heroin and other opioids

Answer 3

Depressant
Activates µ opioid receptors to cause: euphoria, CNS depression and so clouded mental functioning, going ‘on the nod’, and also constipation, pupilloconstriction and respiratory depression.
Major withdrawal symptoms peak 48-72 h after the last dose and subside after about a week. Symptoms include: craving, restlessness, pain, insomnia, diarrhoea, vomiting, cold flashes, involuntary kicking.
Sudden withdrawal by heavily dependent users in poor health is occasionally fatal.

Question 4

Cannabis (THC)

Answer 4

Depressant
CB1 receptor responsible for psychoactive effects of THC
Acute: analgesia, hypolocomotion, increase HR, conjunjunctival redenning, increased appetite, hypothermia, catalepsy
Psychological effects: euphoria (or dysphoria with high doses), visual distortions, impaired hearing, depersonalisation and dissociation, difficulty concentrating, altered sense of time passing (short-term memory impairment)
Tolerance is displayed in cardiac and psychoactive effects
Panic attacks, depression, mania and schizophrenia may occur with adolescent exposure.
The withdrawal syndrome is mild and includes irritability, sleep disturbance, nausea, vomiting, excessive sweating and salivation.

Question 5

Alcohol

Answer 5

Depressant
Mechanism of action is not well understood.
High doses cause dyspepsia
Inhibits vasopressin
Long-term use causes neuropathies, myopathy (inc. cardiomyopathy), hepatotoxicity (cirrhosis), haematological disorders, obesity, malnourishment
Suicide very common in alcoholics
Withdrawal symptoms include confusion, delusions, tremor, tactile and visual hallucinations, convulsions and cardiovascular collapse. There is a 15-50% mortality rate.

Question 6

Ketamine

Answer 6

Hallucinogen, dissociative
Open channel blocker of NMDA glutamate receptors - reduces excitatory transmission and promotes 5-HT transmission.
Acute effects include dissociation, trance-like state and anaesthesia.
Higher doses elicit a ‘K-hole’ experience, combining dissociation with hallucinations
Long-term use may cause memory problems and ulcerative cystitis.

Question 7

Ecstasy (/MDMA/E/Molly)

Answer 7

Hallucinogen (psychedelic) as well as stimulant
Acts on SERT/SLC6A2 and VMAT2/SLC18A2 monoamine transporters, causing increased monoamine (5-HT, NA, DA) neurotransmission.
Acute effects: interoception, reduces inhibition, energising, enhanced enjoyment from tactile experiences, increased intensity of sounds/colours, distortions of time and perception.
High doses can interfere with temperature regulation, causing hyperthermia and organ failure.
Tolerance develops.
Cardiovascular risks similar to cocaine.
Withdrawal symptoms include fatigue, loss of appetite, depression and trouble concentrating.

Question 8

Muscimol

Answer 8

Hallucinogen, psychedelic
GABA-A (ionotropic) agonist
Acute effects: euphoria and psychedelic experiences, including out-of-body experiences and synaesthesia.
There are limited reports of long-term effects or withdrawal.

Question 9

Addiction treatment: Methadone

Answer 9

Substitution/replacement therapy
Long-lasting oral opioid that prevents withdrawal and cravings and blocks the effects of illicit opiate use

Question 10

Addiction treatment: Varenicline

Answer 10

Substitution/replacement therapy
Nicotinic receptor partial agonist, used to quit smoking

Question 11

Addiction treatment: Naltrexone

Answer 11

Long-acting opioid antagonist. It lacks all the effects of self-administered opiates, including euphoria. It can also reduce alcohol cravings.