Methamphetamine is a sympathomimetic amine that belongs to a class of compounds, the phenethylamines, with a variety of stimulant, anorexiant, euphoric, and hallucinogenic effects. Methamphetamine was first synthesized in 1893. Thirty years later, pharmaceutical formulations were introduced as treatments for nasal congestion and asthma. Methamphetamine was widely used by German, Japanese, and American forces during World War II to increase alertness and decrease fatigue.
Methamphetamine is used clinically for treatment of attention deficit disorder with hyperactivity (ADHD), short-term treatment of obesity, and as an off-label treatment for narcolepsy. Recreational use of methamphetamine and other amphetamine-derived stimulants has reached epidemic proportions in the United States, southern Asia, the Philippines, and Japan. After cannabis, it is the most widely abused drug worldwide . Approximately 5 percent of the United States population has used methamphetamine, with an estimated 500,000 people using the drug in a given month. [2-5].
Methamphetamine may be synthesized via simple reactions using readily available chemicals and over-the-counter cold medicines, such as ephedrine and pseudoephedrine. Although some illicit methamphetamine is diverted pharmaceutical product, the majority of recreational methamphetamine is manufactured specifically for illicit use. The output of thousands of small laboratories in predominantly rural regions of the United States has been supplanted by "superlabs" whose output is kilogram quantities. Clandestine methamphetamine synthesis carries significant risk of explosion or toxic exposure and is responsible for exposing many children to profoundly toxic products .
This topic review will discuss the toxicology, diagnosis, and management of acute methamphetamine intoxication. The general management of acute drug overdose and the management of other stimulants, such as cocaine, are discussed elsewhere. (See "General approach to drug poisoning in adults" and "Cocaine: Acute intoxication".)
PHARMACOLOGY AND CELLULAR TOXICOLOGY
Phenethylamines comprise a class of central nervous system (CNS) stimulants (figure 1). Various substitutions on the basic phenethylamine structure determine the degree of CNS penetration, likelihood of degradation by monoamine oxidase (MAO), receptor binding affinity, and the range of effects.