|Systematic (IUPAC) name|
|Trade names||Vicks VapoInhaler|
|Medical: Inhalation (nasal)
Recreational: Oral, intravenous, insufflation, inhalation, suppository
|(what is this?)|
Levomethamphetamine[note 1] is the levorotary (L-enantiomer) form of methamphetamine. Levomethamphetamine is a sympathomimetic vasoconstrictor which is the active ingredient used in some over-the-counter nasal decongestants including the US formulation of Vicks VapoInhaler, but not the Canadian or Indian formulations, which contain only menthol and camphor.
Levomethamphetamine is a TAAR1 agonist, so it affects the central nervous system, although its effects are weaker and somewhat shorter than those of dextromethamphetamine; it is not thought to possess the same addiction potential as that of racemic methamphetamine or dextromethamphetamine. Among its few physiological effects are the vasoconstriction that makes it useful for nasal decongestion. The elimination half-life of levomethamphetamine is between 13.3 and 15 hours, whereas dextromethamphetamine has a half-life of about 10.5 hours.
Levomethamphetamine is the chemical precursor of the antiparkinson's drug selegiline. Selegiline, a selective monoamine oxidase B (MAOB) inhibitor,[note 2] is also metabolized into levomethamphetamine and levoamphetamine. This has caused users to test positive for amphetamines.
Selegiline itself has neuroprotective and neuro-rescuing effects, but concern over the resulting levomethamphetamine's neurotoxicity[note 3] led to development of alternative MAOB inhibitors such as rasagiline, that do not produce toxic metabolites.
When the nasal decongestant is taken in excess, levomethamphetamine has potential side effects resembling those of other sympathomimetic drugs; these effects include hypertension (elevated blood pressure), tachycardia (rapid heart rate), nausea, stomach cramps, dizziness, headache, and tremors.
In a study of psychoactive effects of levomethamphetamine, the intravenous administration of 0.5 mg/kg (but not 0.25 mg/kg) in recreational methamphetamine users produced scores of "drug liking" similar to racemic methamphetamine, but the effects were shorter lived. The study did not test the oral administration of levomethamphetamine. Currently there are no studies demonstrating "drug liking" scores of oral levomethamphetamine that are similar to racemic methamphetamine or dextromethamphetamine in either recreational users or medicinal users.
- Other names include l-methamphetamine, levodesoxyephedrine, l-desoxyephedrine, levmetamfetamine (INN and USAN)
- It is a selective MAOB inhibitor at normal clinical doses. MAOB is an enzyme that metabolizes dopamine, the neurotransmitter deficient in Parkinson's Syndrome.
- And neurotoxicity of other metabolites.
- "Classification". Levmetamfetamine. PubChem Compound. NCBI. Retrieved 17 October 2014.
- Melega, WP; Cho, AK; Schmitz, D; Kuczenski, R; Segal, DS (February 1999). "l-methamphetamine pharmacokinetics and pharmacodynamics for assessment of in vivo deprenyl-derived l-methamphetamine". The Journal of pharmacology and experimental therapeutics 288 (2): 752–8. PMID 9918585.
- Mendelson, J; Uemura, N; Harris, D; Nath, RP; Fernandez, E; Jacob P, 3rd; Everhart, ET; Jones, RT (October 2006). "Human pharmacology of the methamphetamine stereoisomers". Clinical pharmacology and therapeutics 80 (4): 403–20. doi:10.1016/j.clpt.2006.06.013. PMID 17015058.
- Kuczenski, R; Segal, DS; Cho, AK; Melega, W (February 1995). "Hippocampus norepinephrine, caudate dopamine and serotonin, and behavioral responses to the stereoisomers of amphetamine and methamphetamine". The Journal of neuroscience : the official journal of the Society for Neuroscience 15 (2): 1308–17. PMID 7869099.
- Pray SW. "Nonprescription Products to Avoid With Hypertension". uspharmacist.com. Retrieved 17 October 2014.
Topical Nasal Decongestants
Most topical nasal decongestants also carry the warning against unsupervised use with hypertension. This includes oxymetazoline (e.g., Afrin), phenylephrine (e.g., Neo-Synephrine), naphazoline (e.g., Privine), and l-desoxyephedrine/levmetamfetamine (e.g., Vicks Vapor Inhaler). When hypertensive patients request a nasal decongestant, the pharmacist can recommend several alternatives. Propylhexedrine (e.g., Benzedrex Inhaler) is not required to carry a warning against unsupervised use with hypertension and may be effective. Another option is the nasal strip (e.g., Breathe Right). When properly applied, the strip can open the nostrils slightly, and perhaps sufficiently to allow the patient to breathe without use of a pharmacologically active ingredient.
- Mendelson J, Uemura N, Harris D, et al. (October 2006). "Human pharmacology of the methamphetamine stereoisomers". Clin. Pharmacol. Ther. 80 (4): 403–20. doi:10.1016/j.clpt.2006.06.013. PMID 17015058.
- Method for the production of selegiline hydrochloride., retrieved 2015-10-04
- Kalász, H.; Magyar, K.; Szőke, É; Adeghate, E.; Adem, A.; Hasan, M. Y.; Nurulain, S. M.; Tekes, K. (2014-01-01). "Metabolism of selegiline [(-)-deprenyl)]". Current Medicinal Chemistry 21 (13): 1522–1530. ISSN 1875-533X. PMID 24350849.
- Magyar, Kálmán (2011-01-01). "The pharmacology of selegiline". International Review of Neurobiology 100: 65–84. doi:10.1016/B978-0-12-386467-3.00004-2. ISSN 0074-7742. PMID 21971003.
- Cody, J. D. (1993-12-01). "Metabolic Precursors to Amphetamine and Methamphetamine". Forensic Science Review 5 (2): 109–127. ISSN 1042-7201. PMID 26270078.
- Cody, John T. (2002-05-01). "Precursor medications as a source of methamphetamine and/or amphetamine positive drug testing results". Journal of Occupational and Environmental Medicine / American College of Occupational and Environmental Medicine 44 (5): 435–450. ISSN 1076-2752. PMID 12024689.
- Tabakman R, Lecht S, Lazarovici P (2004). "Neuroprotection by monoamine oxidase B inhibitors: a therapeutic strategy for Parkinson's disease?". BioEssays 26 (1): 80–90. doi:10.1002/bies.10378. PMID 14696044.
- Kong, Ping; Zhang, Benshu; Lei, Ping; Kong, Xiaodong; Zhang, Shishuang; Li, Dai; Zhang, Yun (2015-01-01). "Neuroprotection of MAO-B inhibitor and dopamine agonist in Parkinson disease". International Journal of Clinical and Experimental Medicine 8 (1): 431–439. ISSN 1940-5901. PMC 4358469. PMID 25785014.