Drug Dependence and Abuse

Abstract

Physical dependence and addiction differ in that addiction causes activation of certain dopaminergic pathways in the mesolimbic system. Addiction occurs when this reward circuit is stimulated by drugs which are absorbed rapidly into the body, cross blood–brain barrier and for which tolerance develops. Ethanol is a commonly abused drug and causes greater mortality than several chronic diseases combined. Ethanol is a CNS stimulant at initial doses, it causes depression at higher doses, death occurring by coma. Acute withdrawal or delirium tremens can be life threatening and is treated by benzodiazepines. Disulfiram, acamprosate, and naltrexone help sustain abstinence. Methanol toxicity results from accumulation of formic acid and is treated by inhibiting the enzyme aldehyde dehydrogenase. The most addictive agent, nicotine works by stimulating nicotinic cholinergic receptors. To prevent withdrawal, nicotine substitutes such as patches and gums are used. Vaping poses dangers of its own and its entry has been made illegal in India. Varenicline and bupropion help sustain abstinence. Cannabis has been made legal to consume in some countries, given its low chances of causing tolerance and withdrawal. Nabilone and dronabinol are used medically and act on CB₁ receptors.