Recreational Drug: Heroin Pharmacology

Opioids

• Heroin is a diacetyl derivative of morphine, rapidly deacetylated into morphine in the body
• Analgesic, euphoric, and anti-diarrheal effects
• Impaired cough reflex, nausea, vomiting, and constipation
• Tolerance and dependence, respiratory depression
• Binds and activates mu-opioid receptors, increasing dopamine release
• Metabolites: M3G and M6G (morphine glucuronide)

Stimulants

• Cocaine is derived from Erythroxylum coca plant, with a lifetime use of 11%
• Acute effects: euphoria, loss of appetite, increased alertness, and local anaesthetic
• Binge and crash pattern, inhibition of dopamine, norepinephrine, and serotonin reuptake
• Repeated use: eating and sleeping disorders, respiratory problems, convulsions, and kidney failure
• Acute side effects: damage to nasal membranes and septum, tissue damage due to vasoconstriction
• Chronic use: psychosis, heart failure
• Excessive dosage: tremor, convulsions, respiratory depression, and cardiac arrhythmias

Methamphetamine

• A synthetic homologue of amphetamine, first used in WWII
• Lifetime use of 5.8%
• Initial effects: euphoria, increased alertness, energy, and libido
• Binge and crash pattern, release of dopamine, and blockade of monoamine transporters
• Long half-life (8-30 hours), highly addictive, and intense rush
• Side effects: increased heart rate, breathing, and blood pressure, long-lasting cognitive and emotional changes
• Long-term side effects: meth mouth, cardiac failure, overdose, neurotoxicity, and loss of gray matter

Ecstasy (MDMA)

• First used as an appetite suppressant, lifetime use of 12%
• Tolerance, serotonin syndrome, and binding to serotonin transporters
• Release of serotonin via transporter-mediated exchange, blocking reuptake, and inhibiting vesicular monoamine transporter and monoamine oxidase
• Increased brain and plasma oxytocin concentrations, acute psychosis, and panic attacks
• Long-term serotoninergic neurotoxicity, dose-dependent reduction in 5HT receptors and transport proteins, and axonal damage

Cannabis

• Lifetime use of 36%, mainly used for pain
• THC is the main intoxicant, a CB1 and CB2 receptor partial agonist
• CBD is non-intoxicating, and endocannabinoids are naturally occurring
• Good effects: euphoria, increased appetite, and analgesia
• Bad effects: anxiety, memory impairment, and sedation
• Long-term effects: schizophrenia, addiction, and chronic use

LSD (Hallucinogenic)

• 1% of AU uses in the last 12 months, distorted sensory perception, and synaesthesia
• Loss of boundaries and fear of fragmentation, altered mood, and psychosis symptoms
• Extremely potent, long-lasting up to 10-22 hours, and binds to 5-HT receptors and alpha adrenergic receptors
• Partial agonist at 5HT2A, hallucination, and strong tolerance
• Flashbacks, fatal accidents, bad trips, and precipitation of psychosis

Alcohol (CNS Depressant)

• 77% use in the last 12 months, slurred speech, and motor incoordination
• Increased self-confidence, euphoria/dysphoria, aggressivity, and impairment in intellectual, sensory, and motor performance
• Benefits from moderate drinking: reduced mortality related to heart diseases, increased HDL, and inhibited platelet aggregation
• Inhibition of action at glutamate, NMDA, and kainate receptors, and enhancement of GABA action at GABA A receptors
• Adverse drug interactions, neurological degenerations, chronic gastritis, and liver damage

Tobacco (Psychostimulant)

• Biggest drug-related killer, 11% of the population, highly addictive
• Increased alertness, calming, and improvement of general sensory and motor performance
• Relaxation of skeletal muscle, increased heart rate, and blood pressure
• Decreased GI motility, and nicotine is a nicotinic acetylcholine receptor agonist
• Cancer, coronary heart disease, vascular disease, chronic bronchitis, and harm in pregnancy

Caffeine (Psychostimulant)

• Most widely used psychoactive drug, decreased fatigue, and increased alertness
• Performance enhancement, low doses are pleasant, and high doses are dysphoric
• Diuresis, stimulation of cardiac muscle, and relaxation of smooth muscle
• Small tolerance, no withdrawal, and caffeine is a methylxanthine
• Antagonises adenosine A2A receptors, releasing dopamine, norepinephrine, and serotonin, with few side effects

Opioids

• Heroin is a diacetyl derivative of morphine, rapidly deacetylated into morphine in the body
• Analgesic, euphoric, and anti-diarrheal effects
• Impaired cough reflex, nausea, vomiting, and constipation
• Tolerance and dependence, respiratory depression
• Binds and activates mu-opioid receptors, increasing dopamine release
• Metabolites: M3G and M6G (morphine glucuronide)

Stimulants

• Cocaine is derived from Erythroxylum coca plant, with a lifetime use of 11%
• Acute effects: euphoria, loss of appetite, increased alertness, and local anaesthetic
• Binge and crash pattern, inhibition of dopamine, norepinephrine, and serotonin reuptake
• Repeated use: eating and sleeping disorders, respiratory problems, convulsions, and kidney failure
• Acute side effects: damage to nasal membranes and septum, tissue damage due to vasoconstriction
• Chronic use: psychosis, heart failure
• Excessive dosage: tremor, convulsions, respiratory depression, and cardiac arrhythmias

Methamphetamine

• A synthetic homologue of amphetamine, first used in WWII
• Lifetime use of 5.8%
• Initial effects: euphoria, increased alertness, energy, and libido
• Binge and crash pattern, release of dopamine, and blockade of monoamine transporters
• Long half-life (8-30 hours), highly addictive, and intense rush
• Side effects: increased heart rate, breathing, and blood pressure, long-lasting cognitive and emotional changes
• Long-term side effects: meth mouth, cardiac failure, overdose, neurotoxicity, and loss of gray matter

Ecstasy (MDMA)

• First used as an appetite suppressant, lifetime use of 12%
• Tolerance, serotonin syndrome, and binding to serotonin transporters
• Release of serotonin via transporter-mediated exchange, blocking reuptake, and inhibiting vesicular monoamine transporter and monoamine oxidase
• Increased brain and plasma oxytocin concentrations, acute psychosis, and panic attacks
• Long-term serotoninergic neurotoxicity, dose-dependent reduction in 5HT receptors and transport proteins, and axonal damage

Cannabis

• Lifetime use of 36%, mainly used for pain
• THC is the main intoxicant, a CB1 and CB2 receptor partial agonist
• CBD is non-intoxicating, and endocannabinoids are naturally occurring
• Good effects: euphoria, increased appetite, and analgesia
• Bad effects: anxiety, memory impairment, and sedation
• Long-term effects: schizophrenia, addiction, and chronic use

LSD (Hallucinogenic)

• 1% of AU uses in the last 12 months, distorted sensory perception, and synaesthesia
• Loss of boundaries and fear of fragmentation, altered mood, and psychosis symptoms
• Extremely potent, long-lasting up to 10-22 hours, and binds to 5-HT receptors and alpha adrenergic receptors
• Partial agonist at 5HT2A, hallucination, and strong tolerance
• Flashbacks, fatal accidents, bad trips, and precipitation of psychosis

Alcohol (CNS Depressant)

• 77% use in the last 12 months, slurred speech, and motor incoordination
• Increased self-confidence, euphoria/dysphoria, aggressivity, and impairment in intellectual, sensory, and motor performance
• Benefits from moderate drinking: reduced mortality related to heart diseases, increased HDL, and inhibited platelet aggregation
• Inhibition of action at glutamate, NMDA, and kainate receptors, and enhancement of GABA action at GABA A receptors
• Adverse drug interactions, neurological degenerations, chronic gastritis, and liver damage

Tobacco (Psychostimulant)

• Biggest drug-related killer, 11% of the population, highly addictive
• Increased alertness, calming, and improvement of general sensory and motor performance
• Relaxation of skeletal muscle, increased heart rate, and blood pressure
• Decreased GI motility, and nicotine is a nicotinic acetylcholine receptor agonist
• Cancer, coronary heart disease, vascular disease, chronic bronchitis, and harm in pregnancy

Caffeine (Psychostimulant)

• Most widely used psychoactive drug, decreased fatigue, and increased alertness
• Performance enhancement, low doses are pleasant, and high doses are dysphoric
• Diuresis, stimulation of cardiac muscle, and relaxation of smooth muscle
• Small tolerance, no withdrawal, and caffeine is a methylxanthine
• Antagonises adenosine A2A receptors, releasing dopamine, norepinephrine, and serotonin, with few side effects

Learn about the history, modern use, pharmacological effects, mechanism of action, and side effects of heroin, a recreational drug and opioid derivative.