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Drugs of Abuse - Coggle Diagram
Drugs of Abuse
Exogenous Cannabinoids (CBD & THC)
Usually smoked, poor oral absorption (bioavailabililty of THC is 5-20%)
THC is psychoactive component - powerful dose-dependent perceptual changes, fast initial onset of effects (euphoria & relaxation), long terminal half-life of 21.5 hours
CBD - longer terminal half-life of 56-61 hours
Medicinal properties - hypothesised relief of chemotherapy induced N&V, appetite stimulant in people living with HIV (PLWH), relief of chronic pain
Dependence, revealed by withdrawal syndrome - acute effects are usually mild, heavy daily use associated with panic attacks, acute psychosis, hallucinations
Treatment - symptomatic support, Benzodiazepines (for severe reactions)
Opiods
Endo/exogenous agonists at opioid receptors (δ, μ, and κ)
Commonly abused opioids interact with μ-receptor (morphine, heroin, codeine)
Heroin - greater availability, higher potency than morphine, can be taken IV, IM, subcut, inhaled, smoked, relatively short acting, effects wear off in 3-5 hours
Physical dependence develops readily with prolonged, regular use + tolerance occurs
Withdrawal
Occurs with abrupt discontinuation of drugs used for long-term abuse
Signs are generally opposite to those induced by drug
Rate & severity of withdrawal lessened by tapered cessation of drug
Symptoms: N&V, diarrhoea, insomnia, myalgia, sweating, mydriasis, lacrimation, rhinorrhoea, agitation, tachycardia, raised BP
Too rapid withdrawal of drug can be life-threatening - same as with CNS depressants (benzos & barbiturates)
Treatment
Long-acting opiods (detoxification & substitution therapy) -
Buprenorphine & Methadone
Naltrexone - μ-receptor antagonist competitively blocks effects of heroin, has longer duration of action, needs high motivation from patient & must be opioid free for 7-10 days before
Naloxone
- competitive μ-receptors antagonist (opioid overdose), reverses effects of morphine/heroin within minutes
Useful definitions
Intoxication
Transient syndrome, recent substance ingestion, psychological & physical impairment
Drug dependence
Compulsion to take a drug, to experience a psychological effect, or to avoid the discomfort of withdrawal, either physical/psychological or combination of both
Tolerance
An adaptive state with necessity to progressively increase the dose to have the same effect
Withdrawal
Intense physical disturbances when the administration of a drug is terminated, or action reversed by an antagonist
Addiction
Complusive, relapsing drug use despite negative consequences, triggered by cravings in response to contextual cues
Psychomotor stimulants
Cocaine
Amphetamines
Alcohol
Benzodiazepines