|Systematic (IUPAC) name|
|Trade names||Eldepryl, Selgene|
|Licence data||US FDA:|
|Oral, transdermal, buccal|
|Bioavailability||4.4% (oral, fasted), 20% (oral, after food), 18% (patch)|
|Biological half-life||10 hours (oral), 18-25 hours (transdermal)|
|ATC code||N04 QN06|
|Molecular mass||187.281 g/mol|
|(what is this?)|
Selegiline (Anipryl, L-deprenyl, Eldepryl, Emsam, Zelapar) is a substituted phenethylamine used for the treatment of early-stage Parkinson's disease, depression and dementia. In normal clinical doses it is a selective irreversible MAO-B inhibitor. However, in larger doses it loses its specificity and also inhibits MAO-A. Dietary restrictions are common for MAOI treatments, but special dietary restrictions for lower doses have been found to be unnecessary, and dietary restrictions appear to be unnecessary at standard doses when selegiline is taken as Emsam, the transdermal patch form, as no adverse events due to diet have ever been reported with Emsam.
The main use of selegiline is in the treatment of Parkinson's disease. It can be used on its own or in a combination with another agent, most often L-DOPA. For newly diagnosed Parkinson's patients, some claim that selegiline slows the progression of the disease, although this claim has not been widely accepted and the methodology has been rejected by the Food and Drug Administration (FDA).
Selegiline delays the time point when the L-DOPA (levodopa) treatment becomes necessary from 10-12 to 18 months after diagnosis, which is beneficial despite not being definitive evidence of neuroprotection. The rationale for adding selegiline to levodopa is to decrease the required dose of levodopa and thus reduce the motor complications of levodopa therapy.
Comparisons of patients on levodopa + placebo vs levodopa + selegiline showed that selegiline allowed reduction of the levodopa dose by about 40%. Selegiline + levodopa also extended the time until the levodopa dose had to be increased from 2.6 to 4.9 years. As a result, there were fewer motor complications in selegiline groups. In one trial, selegiline + levodopa completely halted the progress of Parkinson's disease over 14 months, while in the placebo + levodopa group the deterioration of the patients' condition continued. However, the interpretation of this trial as proving neuroprotective action of selegiline has been questioned.
As of February 28, 2006, selegiline has also been approved by the FDA to treat major depression using a transdermal patch (Emsam Patch). Selegiline (brand name Anipryl) is also used (at extremely high dosages relative to humans) in veterinary medicine to treat the symptoms of Cushing's disease and cognitive dysfunction (Canine Cognitive Dysfunction) in dogs. As of June 26, 2006, a selegiline transdermal patch is being tested for its effectiveness in treating ADHD.
In February 2006 the US Food and Drug Administration approved Emsam (selegiline), the first transdermal patch for use in treating major depression. The once a day patch works by delivering selegiline through the skin and into the bloodstream. Emsam can be used without the dietary restrictions that are needed for all oral MAO inhibitors that are approved for treating major depression, although the FDA requires warnings concerning dietary restrictions for the 9 and 12 mg doses due to theoretical concerns not supported by any reports of adverse events.
It comes in three sizes that deliver 6, 9, or 12 mg of selegiline per 24 hours. The patch is a matrix containing three layers consisting of a backing, an adhesive drug layer, and a release liner that is placed against the skin. EMSAM was developed by Somerset Pharmaceuticals. In December 2004, Bristol-Myers Squibb and Somerset entered into an agreement that provides Bristol-Myers Squibb with distribution rights to market EMSAM after approval in the United States.
Zelapar is a transmucosal preparation for human administration of selegiline. The quickly-dissolving lozenge is placed between cheek and gum and the medication enters the bloodstream directly. Because hepatic first-pass metabolism is bypassed, the effective dose is lower than oral (swallowed) selegiline. GI side effects are reportedly reduced compared to oral (swallowed) selegiline. Zelapar is manufactured by Valeant Pharmaceuticals.
Minor side effects such as dizziness, dry mouth, insomnia, muscle pain, rash, nausea and constipation have been seen. More serious side effects such as severe headache, tachycardia, arrhythmia, hallucinations, chorea, or difficulty breathing should be investigated by health professionals immediately.
Mechanism of action
Selegiline is a selective inhibitor of MAO-B; MAO-B metabolizes dopamine and phenylethylamine. Selegiline exhibits little therapeutic benefit when used independently, but enhances and prolongs the anti-Parkinson effects of levodopa.
Selegiline's oral bioavailability is drastically increased in females taking oral contraceptives (10- to 20-fold). This could lead to loss of MAO-B selectivity in favor of an MAO-A selectivity, which in turn would make patients susceptible to the usual risks of unselective MAOIs such as tyramine-induced hypertensive crisis and serotonin toxicity when combined with serotonergics such as SSRIs.
N-Desmethylselegiline may have neuroprotective antiapoptotic properties. A large multicenter study suggests a decrease in the disease progression of Parkinsonism but may have reflected other symptomatic response. Desmethylselegiline is metabolized by CYP2C19.
Levoamphetamine and levomethamphetamine
Selegiline is partly metabolized to levomethamphetamine, one of the two enantiomers of methamphetamine, in vivo. A characteristic metabolic pattern was noted, exemplified by a ratio of L-methamphetamine to L-amphetamine of about 2.8. These stereoisomers are moderately less psychoactive and have lower abuse potential compared to their D-isomers.
Selegiline in combination with pethidine is not recommended as it can lead to severe adverse effects; selegiline in combination with the older non-selective MAOIs or in combination with the reversible MAO-A inhibitor moclobemide requires a low tyramine diet. The risk of a true serotonin syndrome with SSRIs and selegiline is quite low and the combination can be taken together without event if caution is used. However, combination of selegiline with fluoxetine can lead to severe reactions.
Possibly due to the structural similarity to illegal stimulants, selegiline has been classified as a controlled substance in Japan and thus can only be obtained with a prescription or special government license.
In E for Ecstasy (a book examining the uses of the street drug Ecstasy in the UK) the writer, activist and Ecstasy advocate Nicholas Saunders highlighted test results showing that certain consignments of the drug also contained selegiline. Consignments of Ecstasy known as "Strawberry" contained what Saunders described as a "potentially dangerous combination of ketamine, ephedrine and selegiline," as did a consignment of "Sitting Duck" Ecstasy tablets.
Selegiline is not a controlled substance in the US, but a prescription is required to obtain it.
Selegiline was discovered in Hungary in the 1960s. József Knoll, a chair of pharmacology at the Semmelweis University in Budapest, was interested in the physiology of "drive" and the differences between high- and low-performing individuals. For his research, he required a molecule that combined amphetamine-like psychostimulant effect with a "psycho-energic" effect of monoamine oxidase inhibitors (MAOI). To do that, he decided to combine in the same molecule the structural features of the MAOI pargyline and the psychostimulant amphetamine.
Knoll was a close friend of Mészáros, the research director of Chinoin, a Hungarian pharmaceutical company (later sold off to Sanofi). For this project, Mészáros put Knoll in contact with a chemist called Ecsery who worked in Chinoin in the field of phenethylamines. Ecsery made about 30 compounds, and Knoll selected the molecule of E-250 (deprenyl) based on its surprising properties. "The great discovery" (in Knoll's words) was that the new molecule did not increase blood pressure, unlike amphetamine, and moreover, it inhibited the blood pressure raising effect of amphetamine.
The first publication on deprenyl in Hungarian appeared in 1964, followed by a paper in English in 1965. Deprenyl is a racemic compound, a mixture of two isomers called enantiomers. For the further pharmaceutical development, Knoll chose the (−)-enantiomer of deprenyl, which caused less hypermotility than the opposite (+)-enantiomer. This (−)-enantiomer (l-deprenyl, R-deprenyl) later has come to be called selegiline.
In 1971, Knoll showed that selegiline selectively inhibits the B-isoform of monoamine oxidase (MAO-B) and proposed that it is unlikely to cause the infamous "cheese effect" (hypertensive crisis resulting from consuming foods containing tyramine) that plagues non-selective MAO inhibitors. A few years later, two Parkinson's researchers based in Vienna, Peter Riederer and Walther Birkmayer, realized that selegiline could be useful in Parkinson's disease. One of their colleagues, Prof. Moussa B.H. Youdim, visited Knoll in Budapest and took selegiline from him to Vienna. In 1975, the Birkmayer's group published the first paper on the effect of selegiline in Parkinson's disease.
In 1967, a Hungarian psychiatrist Ervin Varga observed that racemic deprenyl given in large doses has an antidepressant action. This study was largely forgotten until the 2000s (decade) when Somerset Pharmaceuticals developed a selegiline patch for depression.
- Amsterdam, J. D. (February 2003). "A double-blind, placebo-controlled trial of the safety and efficacy of selegiline transdermal system without dietary restrictions in patients with major depressive disorder". Journal of Clinical Psychiatry 64 (2): 208–14. doi:10.4088/JCP.v64n0216. PMID 12633131.
- Cascade EF, Kalali AH (June 2007). "EMSAM: The First Year". Psychiatry 2007. Retrieved November 30, 2009.
- Riederer P, Lachenmayer L, Laux G (August 2004). "Clinical applications of MAO-inhibitors". Curr. Med. Chem. 11 (15): 2033–43. doi:10.2174/0929867043364775. PMID 15279566.
- Russel Katz, M.D.; et al. "Peripheral and Central Nervous System Advisory Committee Background Package on Azilect" (PDF). FDA. Retrieved December 7, 2011.
- Riederer P, Lachenmayer L (November 2003). "Selegiline's neuroprotective capacity revisited". J Neural Transm 110 (11): 1273–8. doi:10.1007/s00702-003-0083-x. PMID 14628191.
- Ives NJ, Stowe RL, Marro J, et al. (September 2004). "Monoamine oxidase type B inhibitors in early Parkinson's disease: meta-analysis of 17 randomised trials involving 3525 patients". BMJ 329 (7466): 593. doi:10.1136/bmj.38184.606169.AE. PMC 516655. PMID 15310558.
- FDA Approves Emsam (Selegiline) as First Drug Patch for Depression
- Lundgren, Becky. "Canine Cognitive Dysfunction". Veterinary Partner. Retrieved April 8, 2011.
- "Cognitive Dysfunction Syndrome". Long Beach Animal Hospital. Retrieved April 8, 2011.
- "Anipryl consumer information". Drugs.com Vet. Retrieved April 3, 2011.
- Braddock JA, Church DB, Robertson ID, (2004). "Selegiline Treatment of Canine Pituitary-Dependent Hyperadrenocorticism" (PDF). Australian Veterinary Journal. Retrieved April 8, 2011. (PDF)
- "Effectiveness of Selegiline in Treating Marijuana Dependent Individuals". ClinicalTrials.gov. National Institute on Drug Abuse. March 2005. Retrieved February 16, 2007.
- "Usefulness of Selegiline as an Aid to Quit Smoking". ClinicalTrials.gov. National Institute on Drug Abuse. July 2004. Retrieved February 16, 2007.
- http://www.valeant.com/researchAndDevelopment/pipeline/zelapar.jspf[full citation needed]
- http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=medmaster&part=a697046[full citation needed]
- Katzung, Bertram G. Basic & Clinical Pharmacology. 9th Edition. 2004. page 453. Lange Medical Books - McGraw Hill Publishers.
- Katzung. Page 453
- Siu, E. C.; Tyndale, R. F. (2008). "Selegiline is a mechanism-based inactivator of CYP2A6 inhibiting nicotine metabolism in humans and mice". Journal of Pharmacology and Experimental Therapeutics 324 (3): 992–9. doi:10.1124/jpet.107.133900. PMID 18065502.
- Barrett, Jeffrey S.; Szego, Peter; Rohatagi, Shashank; Morales, Richard J.; Dewitt, Kimberly E.; Rajewski, Gregory; Ireland, Joyce (1996). "Absorption and presystemic metabolism of selegiline hydrochloride at different regions in the gastrointestinal tract in healthy males". Pharmaceutical Research 13 (10): 1535–40. doi:10.1023/A:1016035730754. PMID 8899847.
- Laine, Kari; Anttila, Markku; Helminen, Antti; Karnani, Hari; Huupponen, Risto (2001). "Dose linearity study of selegiline pharmacokinetics after oral administration: Evidence for strong drug interaction with female sex steroids". British Journal of Clinical Pharmacology 47 (3): 249–54. doi:10.1046/j.1365-2125.1999.00891.x. PMC 2014223. PMID 10215747.
- Taavitsainen, Paivi; Anttila, Markku; Nyman, Leena; Karnani, Hari; Salonen, Jarmo S.; Pelkonen, Olavi (2000). "Selegiline Metabolism and Cytochrome P450 Enzymes:In vitro Study in Human Liver Microsomes*". Pharmacology and Toxicology 86 (5): 215–21. doi:10.1034/j.1600-0773.2000.d01-38.x. PMID 10862503.
- Engberg, G; Elebring, T; Nissbrandt, H (1991). "Deprenyl (selegiline), a selective MAO-B inhibitor with active metabolites; effects on locomotor activity, dopaminergic neurotransmission and firing rate of nigral dopamine neurons". The Journal of Pharmacology and Experimental Therapeutics 259 (2): 841–7. PMID 1658311.
- http://www.astm.org/JOURNALS/FORENSIC/PAGES/2587.htm[full citation needed]
- Miller GM (January 2011). "The emerging role of trace amine-associated receptor 1 in the functional regulation of monoamine transporters and dopaminergic activity". J. Neurochem. 116 (2): 164–176. doi:10.1111/j.1471-4159.2010.07109.x. PMC 3005101. PMID 21073468.
- Lewin AH, Miller GM, Gilmour B (December 2011). "Trace amine-associated receptor 1 is a stereoselective binding site for compounds in the amphetamine class". Bioorg. Med. Chem. 19 (23): 7044–7048. doi:10.1016/j.bmc.2011.10.007. PMC 3236098. PMID 22037049.
- Heinonen EH, Myllylä V (July 1998). "Safety of selegiline (deprenyl) in the treatment of Parkinson's disease". Drug Saf 19 (1): 11–22. doi:10.2165/00002018-199819010-00002. PMID 9673855.
- Saunders, N., & Heron, L., (1993) E for Ecstasy (Paperback), N. Saunders, London. (ISBN 0950162884)[page needed]
- See:  for details online.
- J. Knoll, E. Sanfai, DE 1568277 (1966).
- J. Hermann Nee Voeroes, Z. Ecsery, G. Sabo, L. Arvai, L. Nagi, O. Orban, E. Sanfai, U.S. Patent 4,564,706 (1986)
- B. Brunova, M. Ferenc, EP 344675 (1989)
- Fowler, Joanna S. (1977). "2-Methyl-3-butyn-2-ol as an acetylene precursor in the Mannich reaction. A new synthesis of suicide inactivators of monoamine oxidase". The Journal of Organic Chemistry 42 (15): 2637–7. doi:10.1021/jo00435a026. PMID 874623.
- Healy, David (2000). "The psychopharmacology of life and death. Interview with Joseph Knoll.". The Psychopharmacologists, Vol. III: Interviews. London: Arnold. pp. 81–110. ISBN 0-340-76110-5.
- Birkmayer W, Riederer P, Youdim MB, Linauer W (1975). "The potentiation of the anti akinetic effect after L-dopa treatment by an inhibitor of MAO-B, Deprenil". J. Neural Transm. 36 (3–4): 303–26. doi:10.1007/BF01253131. PMID 1172524.
- Varga E, Tringer L (1967). "Clinical trial of a new type promptly acting psychoenergetic agent (phenyl-isopropyl-methylpropinyl-HCl, "E-250")". Acta Med Acad Sci Hung 23 (3): 289–95. PMID 6056555.
- Deprenyl (Selegiline) Can Slow Parkinson's Disease Safely According to the British Medical Journal
- FDA Approves Emsam (Selegiline) as First Drug Patch for Depression