Selegiline
Clinical data | |
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Pronunciation | /səˈlɛdʒɪliːn/ sə-LEJ-i-leen |
Trade names | Eldepryl, Jumex, Zelapar, Emsam, others[1] |
Other names | L-Deprenyl; (R)-(–)-N,α-Dimethyl-N-2-propynylphenethylamine; (R)-(–)-N-Methyl-N-2-propynylamphetamine; (R)-(–)-N-2-propynylmethamphetamine |
AHFS/Drugs.com | Monograph |
MedlinePlus | a697046 |
License data |
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Pregnancy category |
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Routes of administration | By mouth, transdermal (patch) |
ATC code | |
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Intestines and liver | |
Metabolites | N-Desmethylselegiline, levoamphetamine, levomethamphetamine |
Elimination half-life | 1.5–3.5 hours (oral),[3] 18–25 hours (transdermal)[4] |
Excretion | Urine |
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Selegiline, also known as L-deprenyl and sold under the brand names Eldepryl, Emsam, Selgin, among other names, is a medication which is used in the treatment of Parkinson's disease and major depressive disorder.[1] It is provided in the form of a capsule or tablet taken by mouth or orally disintegrating tablets taken on the tongue for Parkinson's disease and as a patch applied to skin for depression.
Selegiline acts as a
Medical uses
Parkinson's disease
In its pill form, selegiline is used to treat symptoms of
Selegiline has also been used off-label as a palliative treatment for dementia in Alzheimer's disease.[7]
Depression
Selegiline is also delivered via a transdermal patch used as a treatment for major depressive disorder.[10][11] Administration of transdermal selegiline bypasses hepatic first pass metabolism. This avoids inhibition of gastrointestinal and hepatic MAO-A activity, which would result in an increase of food-borne tyramine in the blood and possible related adverse effects, while allowing for a sufficient amount of selegiline to reach the brain for an antidepressant effect.[12]
A quantitative review published in 2015 found that for the pooled results of the pivotal trials, the number needed to treat (a sign of effect size, so a low number is better) for the patch for symptom reduction was 11, and for remission, was 9.[11] The number needed to harm (inverse of the NNT, a high number here is better) ranged from 387 for sexual side effects to 7 for application site reaction.[11] With regard to the likelihood to be helped or harmed (LHH), the analysis showed that the selegiline patch was 3.6 times as likely to lead to a remission vs. a discontinuation due to side effects; the LHH for remission vs. incidence of insomnia was 2.1; the LHH for remission vs. discontinuation due to insomnia was 32.7. The LHH for remission vs. insomnia and sexual dysfunction were both very low.[11]
Special populations
For all human uses and all forms, selegiline is pregnancy category C: studies in pregnant lab animals have shown adverse effects on the fetus but there are no adequate studies in humans.[5][10]
Side effects
The main side effects of the patch form for depression include application-site reactions, insomnia, diarrhea, and sore throat.[10] The selegiline patch carries a black box warning about a possible increased risk of suicide, especially for young people,[10] as do all antidepressants since 2007.[13]
Interactions
Both the oral and patch forms come with strong warnings against combining selegiline with drugs that could produce
Both forms of the drug carry warnings about
Pharmacology
Pharmacodynamics
Selegiline is a selective inhibitor of
Selegiline potentiates the release of catecholamines independent of its MAO-B inhibiting action. As such, it has been called the "first synthetic catecholaminergic activity enhancer substance".[22][23]
Selegiline also inhibits CYP2A6 and can increase the effects of nicotine as a result.[24] Selegiline also appears to activate σ1 receptors, having a relatively high affinity for these receptors of approximately 400 nM.[25][26]
Pharmacokinetics
Selegiline has an oral
Selegiline is mostly metabolized in the
Buccal administration of selegiline results in 5-fold higher bioavailability, more reproducible blood concentration, and produces fewer amphetamine metabolites than the oral tablet form.[28]
Metabolism
Selegiline is metabolized by cytochrome P450 to L-desmethylselegiline and levomethamphetamine.[29][30] Desmethylselegiline has some activity against MAO-B, but much less than that of selegiline.[20][19] It is thought to be further metabolized by CYP2C19.[31] Levomethamphetamine (the less potent of the two enantiomers of methamphetamine) is converted to levoamphetamine (the less potent of the two enantiomers of amphetamine, with regards to psychological effects).
Due to the presence of these metabolites, people taking selegiline may test positive for "amphetamine" or "methamphetamine" on drug screening tests.
A newer anti-Parkinson MAO-B inhibitor, rasagiline, metabolizes into 1(R)-aminoindan, which has no amphetamine-like characteristics.[36]
Patch
Following application of the patch to humans, an average of 25% to 30% of the selegiline content is delivered systemically over 24 hours. Transdermal dosing results in significantly higher exposure to selegiline and lower exposure to all metabolites when compared to oral dosing; this is due to the extensive first-pass metabolism of the pill form and low first-pass metabolism of the patch form. The site of application is not a significant factor in how the drug is distributed. In humans, selegiline does not accumulate in the skin, nor is it metabolized there.[10]
Chemistry
Selegiline belongs to the
Selegiline is synthesized by the alkylation of (–)-methamphetamine using propargyl bromide.[37][38][39][40]
Another clinically used MAOI of the amphetamine class is tranylcypromine.
History
Following the discovery in 1952 that the tuberculosis drug iproniazid elevated the mood of people taking it, and the subsequent discovery that the effect was likely due to inhibition of MAO, many people and companies started trying to discover MAO inhibitors to use as antidepressants. Selegiline was discovered by Zoltan Ecseri at the Hungarian drug company, Chinoin (part of Sanofi since 1993),[41] which they called E-250.[42]: 66–67 Chinoin received a patent on the drug in 1962 and the compound was first published in the scientific literature in English in 1965.[42]: 67 [43] Work on the biology and effects of E-250 in animals and humans was conducted by a group led by József Knoll at Semmelweis University which was also in Budapest.[42]: 67
Deprenyl is a racemic compound (a mixture of two isomers called
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" (
In the 1970s there was speculation that it could be useful as an
In 1987 Somerset Pharmaceuticals in New Jersey, which had acquired the US rights to develop selegiline, filed a
In the 1990s, J. Alexander Bodkin at McLean Hospital, an affiliate of Harvard Medical School, began a collaboration with Somerset to develop delivery of selegiline via a transdermal patch in order to avoid the well known dietary restrictions of MAO inhibitors.[47][49][50] Somerset obtained FDA approval to market the patch in 2006.[51]
As an anti-aging/longevity drug
Joseph Knoll and his team are credited with having developed selegiline. Although selegeline's development as a potential treatment for Parkinson's, Alzheimer's, and major depressive disorder was headed by other teams, Knoll remained at the forefront of research into the potential longevity enhancing effects of selegiline up until his death in 2018.[52][53][54] Knoll published How Selegiline ((-)-Deprenyl) Slows Brain Aging (2018) wherein he claims that:
"In humans, maintenance from sexual maturity on (-)-deprenyl (1mg daily) is, for the time being, the most promising prophylactic treatment to fight against the age related decay of behavioral performances, prolonging life, and preventing or delaying the onset of age-related neurodegenerative diseases such as Parkinson's and Alzheimer's".[55]
The mechanism of selegiline's longevity-promoting effect has been researched by several groups, including Joseph Knoll and his associates at Semmelweis University, Budapest.[56] The drug has been determined to be a catecholaminergic activity enhancer when present in minuscule concentrations far below those at which monoamine oxidase inhibitory activity can be observed, thereby potentiating the release of catecholamine neurotransmitters in response to stimuli. Knoll maintains that micro-doses of selegiline act as a synthetic analogue to a known or unknown trace amine in order to preserve the brain catecholaminergic system, which he perceives as integral to the organism's ability to function in an adaptive, goal-directed and motivated manner during advancing physical age:
" ... enhancer regulation in the catecholaminergic brain stem neurons play[s] a key role in controlling the uphill period of life and the transition from adolescence to adulthood. The results of our longevity studies support the hypothesis that quality and duration of life rests upon the inborn efficiency of the catcholaminergic brain machinery, i.e. a high performing, long-living individual has a more active, more slowly deteriorating catecholaminergic system than its low performing, shorter living peer. Thus, a better brain engine allows for a better performance and a longer lifespan.
...
Since the catecholaminergic and serotonergic neurons in the brain stem are of key importance in ensuring that the mammalian organism works as a purposeful, motivated, goal-directed entity, it is hard to overestimate the significance of finding safe and efficient means to slow the decay of these systems with passing time. The conclusion that the maintenance on (-)-deprenyl that keeps the catecholaminergic neurnsn a higher activity level is a safe and efficient anti- aging therapy follows from the discovery of the enhancer regulation in the catecholaminergic neurons of the brain stem. From the finding that this regulation starts working on a high activity level after weaning and the enhanced activity subsists during the uphill period of life, until sexual hormones dampen the enhancer regulation in the catecholaminergic and serotonergic neurons in the brain stem, and this event signifies the transition from developmental longevity into postdevelopmental longevity, the downhill period of life."[55]
As a nootropic/"smart drug"
Selegiline is considered by some to be a
Society and culture
In
David Pearce wrote The Hedonistic Imperative[64] six weeks after starting taking selegiline.[65]
In Gregg Hurwitz's novel Out of the Dark,[66] selegiline (Emsam) and tyramine-containing food were used to assassinate the president of the United States.
Veterinary use
In
Selegiline's efficacy in treating pituitary-dependent hyperadrenocorticism has been disputed.
Side effects in dogs are uncommon, but they include vomiting, diarrhea, diminished hearing,
Selegiline does not appear to have a clinical effect on horses.[72]
ADHD research
Selegiline has been limitedly studied in the treatment of attention deficit hyperactivity disorder (ADHD) in both children/adolescents and adults.[73][74] In a small randomized trial of selegiline for treatment of ADHD in children, there were improvements in attention, hyperactivity, and learning/memory performance but not in impulsivity.[75] A small clinical randomized trial compared selegiline to methylphenidate, a first line treatment for ADHD, and reported equivalent efficacy as assessed by parent and teacher ratings.[76] In another small randomized controlled trial of selegiline for the treatment of adult ADHD, a high dose of the medication for 6 weeks was not significantly more effective than placebo in improving symptoms.[74][77][78]
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