Methamphetamine is a potent CNS stimulant that is readily produced illicitly.14,18 In the brain, it acts by both increasing release of dopamine and blocking its re-absorption, causing hyperstimulation of receptor neurons. Methamphetamine is also a cardiovascular stimulant. It blocks re-uptake of norepinephrine and causes an increase in catecholamine release. The euphoric effect is similar to cocaine but may last as long as ten times that of cocaine. Methamphetamine is metabolized to amphetamine, its major active metabolite. Amphetamine itself is rarely encountered. In overdoses, meth-amphetamine causes restlessness, confusion, hallucinations, coma, convulsions, and cardiac arrhythmias. With chronic abuse, just like cocaine, it can produce a chemical paranoid psychosis. Methamphetamine may be sold as cocaine. It is usually taken orally or intravenously though it may be snorted or smoked. Methamphetamine may be transformed into amphetamine hydrochloride ("ice") which is smoked like crack cocaine. Methamphetamine has a half-life of 11-12 hours, with 45% excreted in urine unchanged over a number of days. Long-term use may be associated with myocardial fibrosis.22,23 Chronic use of methamphetamine may cause psychoses24 that can persist for months. Just like cocaine, methamphetamine-related deaths are generally not dose related. There is substantial overlap in blood metham-phetamine concentrations in individuals dying of a methamphetamine overdose and those in whom it is an incidental finding.23,25 The highest concentrations were, however, seen in the drug overdose deaths. Just like cocaine, individuals may die suddenly during or immediately after a manic episode.
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