| Item |
Information |
|
Drug Groups
|
illicit; approved |
|
Description
|
Methamphetamine is a psychostimulant and sympathomimetic drug. It is a member of the amphetamine group of sympathomimetic amines. Methamphetamine can induce effects such as euphoria, increased alertness and energy, and enhanced self-esteem. It is a scheduled drug in most countries due to its high potential for addiction and abuse. |
| Indication |
For the treatment of Attention Deficit Disorder with Hyperactivity (ADHD) and exogenous obesity. |
| Pharmacology |
Methamphetamine is a potent central nervous system stimulant which affects neurochemical mechanisms responsible for regulating heart rate, body temperature, blood pressure, appetite, attention, mood and responses associated with alertness or alarm conditions. The acute effects of the drug closely resemble the physiological and psychological effects of an epinephrine-provoked fight-or-flight response, including increased heart rate and blood pressure, vasoconstriction (constriction of the arterial walls), bronchodilation, and hyperglycemia (increased blood sugar). Users experience an increase in focus, increased mental alertness, and the elimination of fatigue, as well as a decrease in appetite. |
| Toxicity |
Manifestations of acute overdosage with methamphetamine include restlessness, tremor, hyperreflexia, rapid respiration, confusion, assaultiveness, hallucinations, panic states, hyperpyrexia, and rhabdomyolysis. Fatigue and depression usually follow the central stimulation. Cardiovascular effects include arrhythmias, hypertension or hypotension, and circulatory collapse. Gastrointestinal symptoms include nausea, vomiting, diarrhea, and abdominal cramps. Fatal poisoning usually terminates in convulsions and coma. |
| Affected Organisms |
| • |
Humans and other mammals |
|
| Biotransformation |
Hepatic. The primary site of metabolism is in the liver by aromatic hydroxylation, N-dealkylation and deamination. At least seven metabolites have been identified in the urine, with the main metabolites being amphetamine (active) and 4-hydroxymethamphetamine. Other minor metabolites include 4-hydroxyamphetamine, norephedrine, and 4-hydroxynorephedrine. |
| Absorption |
Methamphetamine is rapidly absorbed from the gastrointestinal tract with peak methamphetamine concentrations occurring in 3.13 to 6.3 hours post ingestion. Methamphetamine is also well absorbed following inhalation and following intranasal administration. It is distributed to most parts of the body. Because methamphetamine has a high lipophilicity it is distributed across the blood brain barrier and crosses the placenta. |
| Half Life |
The biological half-life has been reported in the range of 4 to 5 hours. |
| Elimination |
Excretion occurs primarily in the urine, the rate of which is dependent on urine pH. Between 30-54% of an oral dose is excreted in urine as unchanged methamphetamine and 10-23% as unchanged amphetamine. Following an intravenous dose, 45% is excreted as unchanged parent drug and 7% amphetamine. |
| References |
| • |
Schepers RJ, Oyler JM, Joseph RE Jr, Cone EJ, Moolchan ET, Huestis MA: Methamphetamine and amphetamine pharmacokinetics in oral fluid and plasma after controlled oral methamphetamine administration to human volunteers. Clin Chem. 2003 Jan;49(1):121-32.
[Pubmed]
|
| • |
McGregor C, Srisurapanont M, Jittiwutikarn J, Laobhripatr S, Wongtan T, White JM: The nature, time course and severity of methamphetamine withdrawal. Addiction. 2005 Sep;100(9):1320-9.
[Pubmed]
|
| • |
Bennett BA, Hollingsworth CK, Martin RS, Harp JJ: Methamphetamine-induced alterations in dopamine transporter function. Brain Res. 1998 Jan 26;782(1-2):219-27.
[Pubmed]
|
| • |
Hasan AA, Ciancio S: Relationship between amphetamine ingestion and gingival enlargement. Pediatr Dent. 2004 Sep-Oct;26(5):396-400.
[Pubmed]
|
| • |
Shaner JW: Caries associated with methamphetamine abuse. J Mich Dent Assoc. 2002 Sep;84(9):42-7.
[Pubmed]
|
|
| External Links |
|
|