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4. PSYCHOPHARMACOLOGY OF DEPENDENCE FOR DIFFERENT DRUG CLASSES
Effects of prolonged use Changes in dopamine receptor binding and function; decreased cognitive function; psychiatric and neurological sequelae Acute or chronic psychotic episodes, flashbacks or re-experiencing of drug effects long after drug use
Increased susceptibility
Summary of characteristics of selected psychoactive substances (continued)
Withdrawal to seizures No evidence
Tolerance Some tolerance develops (difficult to estimate) Tolerance develops rapidly to physical and psychological effects
Behavioural effects Dizziness, disorientation, euphoria, light- headedness, increased mood, hallucinations, delusions, incoordination, visual disturbances, anxiolysis, sedation Increased heart rate, blood pressure, body temperature; decreased appetite, nausea, vomiting, motor incoordination, papillary dilatation, hallucinations
Primary mechanism of action Most likely GABA-A receptor mediated Varies: LSD: serotonin autoreceptor agonist PCP: NMDA glutamate receptor antagonist Atropinics: muscarinic cholingergic receptor antagonists
Table 4.1 Substance Volatile solvents Hallucinogens
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