25. Drug abuse and dependence. Psychomotor stimulants, psychedelics, cannabis

Last updated on June 15, 2019 at 10:37

Abuse of amphetamines

The most frequently abused amphetamines are methamphetamine, dextroamphetamine, mephedrone and “bath salts”.

Dosage:

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.

Dosage:

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, and its main danger lies in its role as a “gateway drug” to harder drugs.

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.


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