Methamphetamine

Methamphetamine is a psychostimulant and sympathomimetic drug. The Methamphetamine dextrorotatory (S-isomer) dextromethamphetamine can be prescribed to treat attention-deficit hyperactivity disorder, though unmethylated methamphetamine is more commonly prescribed. Narcolepsy and obesity can also be treated by the aforementioned isomer under the brand name Desoxyn. Methamphetamine is considered a second line of treatment, used when amphetamine and methylphenidate cause the patient too many side effects. It is only recommended for short term use (~6 weeks) in obesity patients because it is thought that the anorectic effects of the drug are short lived and produce tolerance quickly, whereas the effects on CNS stimulation are much less susceptible to tolerance. It is also used illegally for weight loss and to maintain alertness, focus, motivation, and mental clarity for extended periods of time, and for recreational purposes.

Methamphetamine enters the brain and triggers a cascading release of norepinephrine, dopamine and serotonin. To a lesser extent methamphetamine acts as a dopaminergic and adrenergic reuptake inhibitor and in high concentrations as a monamine oxidase inhibitor (MAOI). Since it stimulates the mesolimbic reward pathway, causing euphoria and excitement, it is prone to abuse and addiction. Users may become obsessed or perform repetitive tasks such as cleaning, hand-washing, or assembling and disassembling objects. Withdrawal is characterized by excessive sleeping, eating, and depression-like symptoms, often accompanied by anxiety and drug-craving. Users of methamphetamine sometimes take sedatives such as benzodiazepines as a means of easing their "come down".

Common nicknames for methamphetamine include "meth", "jib", "ice", "bikkies", "crystal", "tina", "p", "glass", "yaa baa" (Thailand), and "syabu" (Malaysia). Methamphetamine is sometimes referred to as "speed", but this term is usually used for regular amphetamine or dextroamphetamine.

History

Methamphetamine was first synthesized from ephedrine in Japan in 1893 by chemist Nagayoshi Nagai. In 1919, crystallized methamphetamine was synthesized by Akira Ogata via reduction of ephedrine using red phosphorus and iodine. The related compound amphetamine was first synthesized in Germany in 1887 by Lazar Edeleanu.

Pharmacokinetics

The half life of methamphetamine is 9–15 hours. It is excreted by the kidneys and its half life depends on urinary pH. One of the metabolites of methamphetamine is amphetamine.

Methamphetamine Addiction

Methamphetamine is addictive, especially when injected or smoked. While not life-threatening, withdrawal is often intense and, as with all addictions, relapse is common. 12 Step meetings, such as Crystal Meth Anonymous are available to combat relapse.

Methamphetamine-induced hyperstimulation of pleasure pathways leads to anhedonia. It is possible that daily administration of the amino acids L-Tyrosine and L-5HTP/Tryptophan can aid in the recovery process by making it easier for the body to reverse the depletion of Dopamine, Norepinephrine, and Serotonin. Although studies involving the use of these amino acids have shown some success, this method of recovery has not been shown to be consistently effective.

It is shown that taking ascorbic acid prior to using methamphetamine may help reduce acute toxicity to the brain, as rats given the human equivalent of 5-10 grams of ascorbic acid 30 minutes prior to methamphetamine dosage had toxicity mediated, yet this will likely be of little avail in solving the other serious behavioral problems associated with methamphetamine use and addiction that many users experience. Large doses of ascorbic acid also lower urinary pH, reducing methamphetamine's elimination half-life and thus decreasing the duration of its actions.

To combat addiction, doctors are beginning to use other forms of amphetamine such as dextroamphetamine to break the addiction cycle in a method similar to the use of methadone in the treatment of heroin addicts. There are no publicly available drugs comparable to naloxone, which blocks opiate receptors and is therefore used in treating opiate dependence, for use with methamphetamine problems. However, experiments with some monoamine reuptake inhibitors such as indatraline have been successful in blocking the action of methamphetamine. There are studies indicating that fluoxetine, bupropion and imipramine may reduce craving and improve adherence to treatment. Research has also suggested that modafinil can help addicts quit methamphetamine use.

Haloperidol should never be used for either methamphetamine detoxification procedures or drug-free maintenance protocols. Together with methamphetamine it is hypothesized to be toxic to the substantia nigra and pars reticulata in the brain.

Since the phenethylamine phentermine is a constitutional isomer of methamphetamine, it has been speculated that it may be effective in treating methamphetamine addiction. Although phenteremine is a central nervous stimulant that acts on dopamine and norepinephrine, it has not been reported to cause the same degree of euphoria that is associated with other amphetamines.

Abrupt interruption of chronic methamphetamine use results in the withdrawal syndrome in almost 90% of the cases. Withdrawal of amphetamine often causes a depression which is longer and deeper than even the depression from cocaine withdrawal.

Depression which is longer and deeper than even the depression from cocaine withdrawal.

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