Clinical data | |
---|---|
Trade names | Eutonyl; Eutron |
Other names | MO-911; A-19120; Lopac-P-8013; NSC-43798; N-Methyl-N-propargylbenzylamine |
MedlinePlus | a682088 |
Routes of administration | Oral [1] [2] |
ATC code | |
Pharmacokinetic data | |
Metabolites | • N-Methylbenzylamine [3] • N-Propargylbenzylamine [3] • N-Methylpropargylamine [3] • Benzylamine [3] • Propiolaldehyde [3] • Propargylamine [3] • Benzaldehyde [3] • Pargyline-N-oxide [3] |
Identifiers | |
| |
CAS Number | |
PubChem CID | |
IUPHAR/BPS | |
DrugBank | |
ChemSpider | |
UNII | |
ChEBI | |
ChEMBL | |
CompTox Dashboard (EPA) | |
ECHA InfoCard | 100.008.275 |
Chemical and physical data | |
Formula | C11H13N |
Molar mass | 159.232 g·mol−1 |
3D model (JSmol) | |
| |
| |
(verify) |
Pargyline, sold under the brand name Eutonyl among others, is a monoamine oxidase inhibitor (MAOI) medication which has been used to treat hypertension (high blood pressure) but is no longer marketed. [4] [5] [6] It has also been studied as an antidepressant, but was never licensed for use in the treatment of depression. [7] [8] The drug is taken by mouth. [1] [2]
Side effects of pargyline include orthostatic hypotension among others. [1] It has the potential for serious food and drug interactions with sympathomimetic agents like tyramine that can result in hypertensive crisis. [1] Pargyline acts as a non-selective and irreversible inhibitor of the monoamine oxidases MAO-A and MAO-B. [6] The exact mechanism of the hypotensive effects of pargyline and other MAOIs is unclear. [9] [10] [11] [12] Structurally, pargyline is a benzylamine derivative and is related to selegiline and clorgyline. [13] [14] [15]
Pargyline was first described in 1960 [9] [16] [17] and was introduced for medical use in 1963. [18] It was available in the United States and the United Kingdom. [18] [2] [5] The clinical use of pargyline was limited due to its side effects and interactions. [1] The drug remained available in the United States as late as 2000. [5] However, it was fully discontinued worldwide by 2007. [19]
Pargyline is used as an antihypertensive agent in the treatment of hypertension (high blood pressure). [1] The dosage was 12.5 to 200 mg per day. [1] [12] Its onset of action is slow and several weeks of continuous administration are required for the effects to develop fully upon initiation of treatment. [1] [12] The decrease in blood pressure with pargyline is described as impressive and is especially strong when standing. [1] [12] However, the blood pressure decrease with pargyline is often difficult to control adequately. [1]
Pargyline shares its mechanism of action, monoamine oxidase inhibition, with a class of antidepressants that includes phenelzine, tranylcypromine, and isocarboxazid, among others. [18] [6] [7] However, unlike other MAOIs, pargyline itself was never licensed for treatment of depression. [7] [5] In any case, the drug was studied in the treatment of depression [7] [8] and was advertised in the 1960s as an antihypertensive agent that also "brightens emotional outlook". [18]
Orthostatic hypotension (excessively low blood pressure when standing or standing up) is a prominent side effect of pargyline. [1] [12] Other side effects include dry mouth, dizziness, nausea, headaches, increased appetite, nervousness, insomnia, agitation, sedation, manic reactions, and psychotic reactions. [8] [12]
Pargyline has the potential for serious food and drug interactions due to its MAOI actions. [6] This includes hypertensive crisis with intake of norepinephrine releasing agents like tyramine, amphetamine, and ephedrine. [6] Tyramine is found in high concentrations in certain cheeses and other foods and can result in hypertensive crisis often referred to as the "cheese reaction". [6] Episodes of hypertensive crisis can be severe or fatal and this has greatly limited the clinical use of pargyline. [6] Hypertensive crisis with pargyline is treated intravenously with sympatholytic alpha blockers like phentolamine. [1]
Combination of pargyline and the antihypertensive agent methyldopa has been found to result in intense and potentially fatal central nervous system excitation in rodents. [12] [20] [21] [22] [23] This has been said to resemble the effects of amphetamine overdose. [12] [21] [22] The interaction appears to be due to inhibition by pargyline of the metabolism of normally short-lived methyldopa metabolites like α-methyldopamine and α-methylnorepinephrine that act as potent catecholamine releasing agents. [21] [22] Visual hallucinations have been reported with coadministration of pargyline and methyldopa in humans. [24] [20] [23] As such, use of methyldopa in combination with pargyline and other MAOIs is contraindicated. [24] [12] [20] [21] [22]
Pargyline is also a disulfiram-like drug and aldehyde dehydrogenase (ALDH) inhibitor similarly to disulfiram and can produce alcohol intolerance-type reactions with alcohol. [3] [25] [12]
Pargyline is a non-selective and irreversible monoamine oxidase inhibitor (MAOI), or an inhibitor of the monoamine oxidase (MAO) enzyme. [6] This enzyme is involved in the metabolism of the monoamine neurotransmitters serotonin, norepinephrine, and dopamine. [6] [26] Pargyline is said to have slight preference or selectivity for inhibition of MAO-B over MAO-A (IC50 = 8.20 nM and 11.52 nM, respectively). [6] [27] [28] [29] Using rodent systems however, pargyline showed 2- to 356-fold selectivity for MAO-B inhibition over MAO-A inhibition in different studies (compared to 16- to 6401-fold selectivity with selegiline). [30] In relation to the preceding, pargyline has been referred to as a so-called semi-selective MAO-B inhibitor. [31] [32] It has also been found to show some selectivity for MAO-B inhibition with a single dose but results in non-selective inhibition with continuous administration. [32]
Pargyline produces its antihypertensive effects via MAO inhibition. [9] [10] However, the exact mechanism of action by which this occurs is unclear. [9] [10] [11] [12] Pargyline and other MAOIs inhibit the metabolism of norepinephrine and cause accumulation of norepinephrine in the heart, brain, and other adrenergic tissues. [9] [10] [11] [12] Some possibilities include diminished responsiveness to norepinephrine via increased norepinephrine levels in blood vessels and blockade blockade of the release of norepinephrine from peripheral sympathetic neurons. [9] [1] [12] Another possibility is that pargyline increases levels of false neurotransmitters like octopamine and tyramine, which are weaker pressor agents than norepinephrine. [9] [10] [1] [33] However, the involvement of octopamine in the hypotensive effects of pargyline and other MAOIs is uncertain. [9] [1] [33] Yet another possibility is that the hypotensive effects may be due to accumulation of N-acetylserotonin, which shows antihypertensive effects in animals. [9] [34] As of 2018, the precise mechanism of the hypotensive effects of MAOIs still remains unresolved. [9]
In addition to its actions as an MAOI, pargyline has been found to bind with high affinity to the I2 imidazoline receptor. [35] This receptor has been found to actually be an allosteric site on the monoamine oxidase (MAO) enzyme. [6] [35]
A high dose of pargyline (10 mg/kg) has been found to stimulate locomotor activity, a psychostimulant-like effect, in certain behavioral tests in rats. [36] [37] This might be due to its MAOI activity and increased dopamine levels in the nucleus accumbens or might be related to stimulant-like effects of its metabolites including benzylamine, N-methylbenzylamine, and/or N-propargylbenzylamine. [36] [37] However, no studies on this matter have been conducted. [36] [38] Certain other MAOIs, like iproniazid, phenelzine, pheniprazine, and tranylcypromine, but not nialamide, have likewise been found to produce amphetamine- and psychostimulant-like effects at high doses in animals. [39] Several of these agents are known to metabolize into phenethylamines and amphetamines with catecholamine-releasing activity [38] [40] or to have intrinsic catecholamine-releasing actions of their own. [40] [41] [42] Benzylamine derivatives have been found to act as catecholamine reuptake inhibitors. [43]
Pargyline has been found to act as an irreversible aldehyde dehydrogenase (ALDH) inhibitor. [3] [25] It is a disulfiram-like drug and can produce intolerance-type reactions with alcohol similarly to disulfiram. [3] The ALDH inhibition of pargyline appears to be mediated by its metabolites, namely propiolaldehyde, but also propargylamine and benzylamine. [3] [25]
Pargyline has been found to act as a reversible inhibitor of diamine oxidase (DAO)-mediated putrescine metabolism. [25] [44] It has additionally been found to act as a weak inhibitor of arylalkyl acylamidase and of histamine N-methyltransferase. [25] [45] [46]
In contrast to selegiline, pargyline does not appear to show catecholaminergic activity enhancer (CAE)-like effects. [31] [32] [47]
Pargyline has high lipophilicity [48] [26] and is predicted to cross the blood–brain barrier. [26] The drug has been shown to elevate brain monoamine levels, for instance of serotonin norepinephrine, dopamine, and trace amines, in animals. [49] [50]
Pargyline is N-demethylated and N-depropargylated by CYP2E1 to form arylalkylamine and other metabolites including benzylamine, N-methylbenzylamine, and N-propargylbenzylamine, among others. [27] [3] [51] These metabolites may then undergo additional metabolism, for instance hydroxylation and oxidation. [27] [3] [51] It also forms propiolaldehyde and propargylamine. [3] N‐Propargylbenzylamine, which is a major active metabolite of pargyline, is a potent and selective inhibitor of MAO-B in vivo in rats and may contribute importantly to MAO-B inhibition with pargyline. [27] [49] [51] [52] Other metabolites, like propiolaldehyde, are potent ALDH inhibitors. [3]
Pargyline is an derivative of benzylamine and is also known as N-methyl-N-propargylbenzylamine. [13] [48] It is used pharmaceutically as the hydrochloride salt. [4] [5] [13]
Pargyline is a lipophilic compound, with a predicted log P of about 2.1. [48] [26]
Pargyline preceded and is structurally related to the selective and irreversible MAO-B inhibitor selegiline (deprenyl; (R)-(–)-N-methyl-N-propargylamphetamine). [14] [15] [53] Clorgyline (MB-9302; N-methyl-N-propargyl-3-(2,4-dichlorophenoxy)propylamine), another structural analogue of pargyline, is a selective and irreversible MAO-A inhibitor. [54] [55] [56]
Pargyline was first described in the scientific literature in 1960. [9] [16] [17] It was brought to market in the United States and the United Kingdom by Abbott Laboratories in 1963 as an antihypertensive drug. [18] It was one of several MAOIs introduced in the 1960s including nialamide, isocarboxazid, phenelzine, and tranylcypromine. [57] [58] [59] [60] By 2007, the drug was discontinued. [19] As of 2014 [update] , there were no generic versions available in the United States. [2] It continued to be available in the United States as late as 2000. [5]
Pargyline is the generic name of the drug and its INN , BAN , and DCF , while its USAN and BANM in the case of the hydrochloride salt is pargyline hydrochloride. [4] [5] [13] The drug is also known by the developmental code name MO-911. [26] Marketed brand names of pargyline have included Eutonyl and Eutron. [4] [5] [13]
Pargyline has been studied in the treatment of depression. [7] [8] [61] [62] [63] [64] [65] [66]
Monoamine oxidase inhibitors (MAOIs) are a class of drugs that inhibit the activity of one or both monoamine oxidase enzymes: monoamine oxidase A (MAO-A) and monoamine oxidase B (MAO-B). They are best known as effective antidepressants, especially for treatment-resistant depression and atypical depression. They are also used to treat panic disorder, social anxiety disorder, Parkinson's disease, and several other disorders.
Tranylcypromine, sold under the brand name Parnate among others, is a monoamine oxidase inhibitor (MAOI). More specifically, tranylcypromine acts as nonselective and irreversible inhibitor of the enzyme monoamine oxidase (MAO). It is used as an antidepressant and anxiolytic agent in the clinical treatment of mood and anxiety disorders, respectively. It is also effective in the treatment of ADHD.
Selegiline, also known as L-deprenyl and sold under the brand names Eldepryl, Zelapar, and Emsam among others, is a medication which is used in the treatment of Parkinson's disease and major depressive disorder. It has also been studied and used off-label for a variety of other indications, but has not been formally approved for any other use. The medication, in the form licensed for depression, has modest effectiveness for this condition that is similar to that of other antidepressants. Selegiline is provided as a swallowed tablet or capsule or an orally disintegrating tablet (ODT) for Parkinson's disease and as a patch applied to skin for depression.
Deprenyl, also known by its developmental code name E-250 and as N-propargylmethamphetamine, is the racemic mixture of D-deprenyl and L-deprenyl (selegiline). It was discovered in 1961 in Hungary at Chinoin Pharmaceutical Company by Zoltan Ecseri and József Knoll, was patented in 1962, and was first described in the literature in 1964 or 1965.
Dopaminergic means "related to dopamine", a common neurotransmitter. Dopaminergic substances or actions increase dopamine-related activity in the brain.
Moclobemide, sold under the brand names Amira, Aurorix, Clobemix, Depnil and Manerix among others, is a reversible inhibitor of monoamine oxidase A (RIMA) drug primarily used to treat depression and social anxiety. It is not approved for use in the United States, but is approved in other Western countries such as Canada, the UK and Australia. It is produced by affiliates of the Hoffmann–La Roche pharmaceutical company. Initially, Aurorix was also marketed by Roche in South Africa, but was withdrawn after its patent rights expired and Cipla Medpro's Depnil and Pharma Dynamic's Clorix became available at half the cost.
Clorgiline (INN), or clorgyline (BAN), is a monoamine oxidase inhibitor (MAOI) structurally related to pargyline which is described as an antidepressant. Specifically, it is an irreversible and selective inhibitor of monoamine oxidase A (MAO-A). Clorgiline was never marketed, but it has found use in scientific research. It has been found to bind with high affinity to the σ1 receptor (Ki = 3.2 nM) and with very high affinity to the I2 imidazoline receptor (Ki = 40 pM).
Rasagiline, sold under the brand name Azilect among others, is a medication which is used in the treatment of Parkinson's disease. It is used as a monotherapy to treat symptoms in early Parkinson's disease or as an adjunct therapy in more advanced cases. The drug is taken by mouth.
(–)-Benzofuranylpropylaminopentane is an experimental drug related to selegiline which acts as a monoaminergic activity enhancer (MAE). It is orally active in animals.
1-Phenyl-2-propylaminopentane is an experimental drug related to selegiline which acts as a catecholaminergic activity enhancer (CAE).
Monoamine oxidase B (MAO-B) is an enzyme that in humans is encoded by the MAOB gene.
Levoamphetamine is a stimulant medication which is used in the treatment of certain medical conditions. It was previously marketed by itself under the brand name Cydril, but is now available only in combination with dextroamphetamine in varying ratios under brand names like Adderall and Evekeo. The drug is known to increase wakefulness and concentration in association with decreased appetite and fatigue. Pharmaceuticals that contain levoamphetamine are currently indicated and prescribed for the treatment of attention deficit hyperactivity disorder (ADHD), obesity, and narcolepsy in some countries. Levoamphetamine is taken by mouth.
Pheniprazine, formerly sold under the brand names Catron and Cavodil, is an irreversible and non-selective monoamine oxidase inhibitor (MAOI) of the hydrazine group that was used as an antidepressant to treat depression in the 1960s. It was also used in the treatment of angina pectoris and schizophrenia. Pheniprazine has been largely discontinued due to toxicity concerns such as jaundice, amblyopia, and optic neuritis.
d-Deprenyl, also known as or dextro-N-propargyl-N-methylamphetamine, is an MAO-B inhibitor that metabolizes into d-amphetamine and d-methamphetamine and is therefore also a norepinephrine–dopamine releasing agent. It is one of the two enantiomers of deprenyl and is the opposite enantiomer of l-deprenyl (selegiline).
Monoaminergic activity enhancers (MAE), also known as catecholaminergic/serotonergic activity enhancers (CAE/SAE), are a class of compounds that enhance the action potential-evoked release of monoamine neurotransmitters in the nervous system. MAEs are distinct from monoamine releasing agents (MRAs) like amphetamine and fenfluramine in that they do not induce the release of monoamines from synaptic vesicles but rather potentiate only nerve impulse propagation-mediated monoamine release. That is, MAEs increase the amounts of monoamine neurotransmitters released by neurons per electrical impulse.
4-Fluoroselegiline, or p-fluoro-L-deprenyl, is a substituted amphetamine designer drug. It is the 4-fluorinated derivate of selegiline.
Desmethylselegiline (DMS), also known as norselegiline or as N-propargyl-L-amphetamine, is an active metabolite of selegiline, a medication used in the treatment of Parkinson's disease and depression.
The pharmacology of selegiline pertains to the pharmacodynamic and pharmacokinetic properties of the antiparkinsonian and antidepressant selegiline (L-deprenyl). Selegiline is available in a few different forms, including oral tablets and capsules, orally disintegrating tablets (ODTs), and transdermal patches. These forms have differing pharmacological properties.
SU-11739 is an experimental monoamine oxidase inhibitor (MAOI) that was never marketed.
AGN-1135 is a monoamine oxidase inhibitor (MAOI) that was never marketed. It is the racemic form of rasagiline and is a mixture of the R(+)-enantiomer and S(–)-enantiomer (TVP-1022). Like rasagiline, AGN-1135 is a selective monoamine oxidase B (MAO-B) inhibitor. Virtually all of the MAOI activity of AGN-1135 lies in rasagiline, which is several orders of magnitude more potent as an MAO-B inhibitor than the S(–)-enantiomer. In relation to this, enantiopure rasagiline was developed and marketed for use as a pharmaceutical drug rather than AGP-1135.
Two more novel antihypertensives appeared in the advertising pages of the BMJ before the end of 1963. The first was pargyline, brand name Eutonyl, marketed by Abbott. The company had observed that this non-hydrazine MAO inhibitor had, in common with other MAO inhibitors, a hypotensive effect. The text suggested that the drug, when combined with their other drug Enduron (methyclothiazide), allowed a lowering of the dose of Eutonyl (BMJ, 12-10-63). The selling point of Eutonyl was 'lowers blood pressure, brightens emotional outlook'.
The administration of methyldopa to mice pretreated with the MAOI pargyline resulted in central nervous system excitation [van Rossum and Hurkmans, 1963]. Warning was then issued against the concomitant use of MAOIs and methyldopa in humans [van Rossum 1963]. A case of visual hallucinations was reported following the administration of methyldopa to a patient receiving pargyline [Paykel, 1966].
Pargyline was earlier considered to be a selective inhibitor of MAO-B. In an appropriate dose and after a single administration, pargyline shows some selectivity to MAO-B, but when it is given chronically it induces a non-selective inhibition of both enzyme types [38]. [...] selegiline, in contrast to pargyline and tranylcypromine, blocks the release of NA from the storage vesicles of the rat heart [7, 66]. [...] The effects of various MAO-B inhibitors on rabbit arterial strip response to T A were studied recently [Ill]. In addition to selegiline, MDL-72145, Ro 16-6491, AGN-1135, J-508, U-1424, TZ-650 were included in these studies. All of the MAO-B selective inhibitors except selegiline potentiated the effect of T A on the pulmonary artery strip, and similar results were also obtained in anesthetized cats and rats in vivo regarding blood pressure response to T A [ 112]. Tranylcypromine, pargyline, and clorgyline were also shown to be strong potentiators of TA both in vitro and in vivo. Selegiline was the only exception, which indicates that the lack ofT A potentiation is not a general characteristic of MAO-B inhibitors.
The MAO inhibitors are subdivided, not only according to structure (hydrazine or non-hydrazine) but also according to the presence or absence of inherent amphetamine-like activity. Thus high doses of iproniazid, pheniprazine, phenelzine and tranylcypromine directly increase motor activity, whereas nialamide and pargyline do not.
Pargyline is promoted only for the treatment of hypertension, and not for depression.