59. Drug abuse and dependence. Psychomotor stimulants, psychedelics, cannabis
Abuse of amphetamines
The most frequently abused amphetamines are methamphetamine, dextroamphetamine, mephedrone and “bath salts”.
Administration
Amphetamines are mostly taken orally but can be taken IV or by inhalation as well.
Effect
Amphetamines cause locomotor stimulation, euphoria, reduced fatigue, reduced appetite, stereotypical behaviour and sympathetic activation.
MDMA causes psychedelic and hallucinogenic effects.
Dependence
Psychological dependence and to a lesser degree physiological dependence occurs. Tolerance builds to the peripheral effects but not to the central effects.
Intoxication of amphetamines
Acute: Extreme sympathetic activation and organic psychosyndrome. Organic psychosyndrome is characterised by confusion and disorientation.
Chronic: Amphetamine psychosis can occur, which involves hallucinations, paranoid delusions and agitation.
Intoxication of MDMA
Acute: Hyperthermia, seizures, increased perspiration, delusions, hyponatraemia. Excessive sweating and excessive thirst can cause water intoxication and cerebral oedema.
Abstinence (withdrawal)
Amphetamine withdrawal causes cravings, depression, anxiety, sedation and hyperphagia.
Treatment of amphetamines and MDMA intoxication
- Seizures -> benzodiazepines
- Gastric lavage with activated charcoal
- Hypertension, arrhythmia -> α and β-blockers
- Hyperthermia -> cooling
- Metabolic acidosis -> sodium bicarbonate
- Cerebral oedema -> mannitol
Abuse of cocaine
The symptoms of intoxication, the degree of tolerance, the dependence, the withdrawal symptoms and the treatment are similar to those of amphetamine.
Administration
Chewing coca leaves, intranasally or by inhalation.
Effect
Cocaine causes similar effects as amphetamines, like locomotor stimulation, euphoria, reduced fatigue, reduced appetite, stereotypical behaviour and sympathetic activation. Hallucinations is less common in cocaine abuse, and the euphoria lasts shorter.
Dependence
Cocaine causes strong psychological dependence.
Intoxication
Acute: Sweating, chest pain, mydriasis. More severe complications include coronary vasospasm, myocardial infarction, cardiac arrhythmia and rhabdomyolysis.
Chronic: Perforation of nasal septum (if sniffed), cardiomyopathy.
Abuse of caffeine
Caffeine is a methylxanthine derivative. A cup of coffee contains around 100 mg of caffeine.
Effect
It causes mild psychostimulant effect without euphoria and hallucinations. It decreases fatigue and enhances cognitive abilities.
Dependence
Mild psychological and physical dependence develops. Tolerance develops against the central effects.
Intoxication
Intoxication occurs when consuming more than 1 g of caffeine in a day. This causes anxiety, insomnia, tremor, nausea and potentially seizures and arrhythmias. Caffeine overdose is lethal.
Abstinence (withdrawal)
Caffeine withdrawal occurs one or two days after the last cup and involves hypotension, headache, fatigue and irritability.
Abuse of nicotine
Nicotine is found in cigarettes, snus and chewing tobacco. It’s the agonist for nicotinic acetylcholine receptors that gave them their name.
Effect
Nicotine causes a mild psychostimulant effect, decreases stress and improves cognitive functions. It also causes tachycardia, increases peristalsis and can cause nausea.
Dependence
Strong psychological and mild physical dependence develops.
Intoxication
Acute: Bowel spasm, vomiting, sweating, dizziness and anxiety.
Chronic: Decreased sleep quality, teratogenic effects.
Abstinence (withdrawal)
Withdrawal lasts for 2 – 3 weeks and involves irritability, insomnia, increased appetite and impaired cognitive functions.
Treatment
Treatment for intoxication is supportive.
Nicotine addiction can be treated with nicotine replacement therapy, bupropion and varenicline. Bupropion is a nicotinic acetylcholine receptor antagonist which reduces withdrawal and craving. Varenicline is a partial agonist for the nicotinic receptor. It reduces withdrawal.
Abuse of cannabis
The active ingredient in cannabis is THC (tetrahydrocannabinol). It's relatively harmless compared to other drugs of abuse, but cannabis increases the risk of psychosis, schizophrenia, accidents, pulmonary disease, hyperemesis syndrome, and testicular cancer.
Effect
Relaxation, feeling of well-being, increased appetite, analgesia, anti-emetic effect, tachycardia, vasodilation. Vasodilation of vessels in the sclera and conjunctiva are what cause the characteristic redness of the eyes.
Dependence
Moderate psychological and mild physical dependence develops. Moderate tolerance develops.
Intoxication
Acute: Relatively harmless. Drowsiness, anxiety, delusions, impaired reaction time, potentially psychosis.
Chronic: Increased risk for schizophrenia. Negative effect on sex hormones.
Abstinence (withdrawal)
Withdrawal only occurs after regular chronic use. Symptoms include unstable mood, depression and irritability.
Treatment
No treatment is necessary.
Abuse of psychedelics
Psychedelics don’t cause physical dependence and therefore cause no withdrawal symptoms. They also don’t cause strong psychological dependence. They don’t have severe acute intoxications. Tolerance to their action develops quickly. Because of these factors they’re not considered major drugs of abuse.
The lecture doesn’t mention anything about psychedelics like LSD and psilocybin that wasn’t already covered in topic 21, so they’re not repeated here.