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Methamphetamine
INN: Metamfetamine
An image of the methamphetamine compound
Ball-and-stick model of the methamphetamine molecule
Clinical data
Pronunciation/ˌmɛθæmˈfɛtəmn/
Trade namesDesoxyn, Methedrine
SynonymsN-methylamphetamine, N,α-dimethylphenethylamine, desoxyephedrine
AHFS/Drugs.comMonograph
License data
Pregnancy
category
  • US: C (Risk not ruled out)
Dependence
liability
Physical: none
Psychological: high
Addiction
liability
High
Routes of
administration
Medical: oral (ingestion), intravenous
Recreational: oral, intravenous, intramuscular, subcutaneous, smoke inhalation, insufflation, rectal, vaginal
ATC code
Legal status
Legal status
Pharmacokinetic data
BioavailabilityOral: 70%
IV: 100%
Protein bindingVaries widely
MetabolismCYP2D6 and FMO3
Onset of actionRapid
Elimination half-life5–30 hours
Duration of action10–20 hours
ExcretionPrimarily renal
Chemical and physical data
FormulaC10H15N
Molar mass149.24 g·mol−1
ChiralityRacemic mixture
Melting point3 °C (37 °F) (predicted)
Boiling point212 °C (414 °F) at 760 mmHg

Methamphetamine (contracted from N-methylamphetamine) is a potent central nervous system (CNS) stimulant that is mainly used as a recreational drug and less commonly as a second-line treatment for attention deficit hyperactivity disorder and obesity. Methamphetamine was discovered in 1893 and exists as two enantiomers: levo-methamphetamine and dextro-methamphetamine.  Methamphetamine properly refers to a specific chemical, the racemic free base (while INN name metamfetamine refers to single enantiomer, dextromethamphetamine), which is an equal mixture of levomethamphetamine and dextromethamphetamine in their pure amine forms. It is rarely prescribed over concerns involving human neurotoxicity and potential for recreational use as an aphrodisiac and euphoriant, among other concerns, as well as the availability of safer substitute drugs with comparable treatment efficacy. Dextromethamphetamine is a much stronger CNS stimulant than levomethamphetamine.

Both methamphetamine and dextromethamphetamine are illicitly trafficked and sold owing to their potential for recreational use. The highest prevalence of illegal methamphetamine use occurs in parts of Asia, Oceania, and in the United States, where racemic methamphetamine, levomethamphetamine, and dextromethamphetamine are classified as schedule II controlled substances.

Levomethamphetamine is available as an over-the-counter (OTC) drug for use as an inhaled nasal decongestant in the United States. Internationally, the production, distribution, sale, and possession of methamphetamine is restricted or banned in many countries, due to its placement in schedule II of the United Nations Convention on Psychotropic Substances treaty. While dextromethamphetamine is a more potent drug, racemic methamphetamine is sometimes illicitly produced due to the relative ease of synthesis and limited availability of chemical precursors.

In low to moderate doses, methamphetamine can elevate mood, increase alertness, concentration and energy in fatigued individuals, reduce appetite, and promote weight loss. At relatively high doses, it can induce psychosis, breakdown of skeletal muscle, seizures and bleeding in the brain. Chronic high-dose use can precipitate unpredictable and rapid mood swings, stimulant psychosis (e.g., paranoia, hallucinations, delirium, and delusions) and violent behavior. Recreationally, methamphetamine's ability to increase energy has been reported to lift mood and increase sexual desire to such an extent that users are able to engage in sexual activity continuously for several days. Methamphetamine is known to possess a high addiction liability (i.e., a high likelihood that long-term or high dose use will lead to compulsive drug use) and high dependence liability (i.e. a high likelihood that withdrawal symptoms will occur when methamphetamine use ceases). Heavy recreational use of methamphetamine may lead to a post-acute-withdrawal syndrome, which can persist for months beyond the typical withdrawal period. Unlike amphetamine, methamphetamine is neurotoxic to human midbrain dopaminergic neurons. It has also been shown to damage serotonin neurons in the CNS. This damage includes adverse changes in brain structure and function, such as reductions in grey matter volume in several brain regions and adverse changes in markers of metabolic integrity.

Methamphetamine belongs to the substituted phenethylamine and substituted amphetamine chemical classes. It is related to the other dimethylphenethylamines as a positional isomer of these compounds, which share the common chemical formula: C10H15N1.

Uses

Medical

In the United States, dextromethamphetamine hydrochloride, under the trade name Desoxyn, has been approved by the FDA for treating ADHD and obesity in both adults and children; however, the FDA also indicates that the limited therapeutic usefulness of methamphetamine should be weighed against the inherent risks associated with its use. Methamphetamine is sometimes prescribed off label for narcolepsy and idiopathic hypersomnia. In the United States, methamphetamine's levorotary form is available in some over-the-counter (OTC) nasal decongestant products.

As methamphetamine is associated with a high potential for misuse, the drug is regulated under the Controlled Substances Act and is listed under Schedule II in the United States. Methamphetamine hydrochloride dispensed in the United States is required to include a boxed warning regarding its potential for recreational misuse and addiction liability.

Recreational

Methamphetamine is often used recreationally for its effects as a potent euphoriant and stimulant as well as aphrodisiac qualities.
 According to a National Geographic TV documentary on methamphetamine, an entire subculture known as party and play is based around sexual activity and methamphetamine use. Participants in this subculture, which consists almost entirely of homosexual male methamphetamine users, will typically meet up through internet dating sites and have sex. Due to its strong stimulant and aphrodisiac effects and inhibitory effect on ejaculation, with repeated use, these sexual encounters will sometimes occur continuously for several days on end. The crash following the use of methamphetamine in this manner is very often severe, with marked hypersomnia (excessive daytime sleepiness). The party and play subculture is prevalent in major US cities such as San Francisco and New York City.

Desoxyn tablet
Desoxyn tablets – pharmaceutical
methamphetamine hydrochloride
 
Crystal meth
Crystal meth – illicit
methamphetamine hydrochloride

Contraindications

Methamphetamine is contraindicated in individuals with a history of substance use disorder, heart disease, or severe agitation or anxiety, or in individuals currently experiencing arteriosclerosis, glaucoma, hyperthyroidism, or severe hypertension. The FDA states that individuals who have experienced hypersensitivity reactions to other stimulants in the past or are currently taking monoamine oxidase inhibitors should not take methamphetamine. The FDA also advises individuals with bipolar disorder, depression, elevated blood pressure, liver or kidney problems, mania, psychosis, Raynaud's phenomenon, seizures, thyroid problems, tics, or Tourette syndrome to monitor their symptoms while taking methamphetamine. Due to the potential for stunted growth, the FDA advises monitoring the height and weight of growing children and adolescents during treatment.

Side effects

Physical

The physical effects of methamphetamine can include loss of appetite, hyperactivity, dilated pupils, flushed skin, excessive sweating, increased movement, dry mouth and teeth grinding (leading to "meth mouth"), headache, irregular heartbeat (usually as accelerated heartbeat or slowed heartbeat), rapid breathing, high blood pressure, low blood pressure, high body temperature, diarrhea, constipation, blurred vision, dizziness, twitching, numbness, tremors, dry skin, acne, and pale appearance.

Meth mouth