Chapter 25: Drugs of Abuse

Drugs of Abuse defines drug dependence through the dual lenses of psychological craving, driven by the activation of dopaminergic pathways in the nucleus accumbens, and physical neuroadaptation, which results in specific withdrawal syndromes when a substance is discontinued. The text systematically categorizes these substances, beginning with central nervous system depressants like ethanol, which enhances inhibitory neurotransmission, and toxic alcohols like methanol that require specific metabolic interventions. It further details the risks associated with sedative-hypnotics, such as benzodiazepines and the predatory drug flunitrazepam, as well as the escalating crisis of opioid abuse involving heroin, fentanyl, and prescription analgesics. Stimulants, including cocaine and various amphetamine derivatives, are analyzed for their ability to increase synaptic concentrations of dopamine and norepinephrine, with special attention to the neurotoxic potential of MDMA and the widespread use of nicotine and caffeine. The chapter also covers the unique effects of cannabis and its primary constituent THC, hallucinogens like LSD that alter sensory perception through serotonin receptors, and dissociative agents like PCP. Beyond illicit substances, it addresses the significant public health impacts of prescription drug misuse, the abuse of over-the-counter medications like dextromethorphan and diphenhydramine, and the dangerous use of anabolic steroids and inhalants. The concluding sections focus on clinical management, detailing pharmacological strategies for treating intoxication and long-term dependence using agents like methadone, buprenorphine, naltrexone, and varenicline to support recovery and prevent relapse.