Clinical data | |
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Trade names | Parnate, many generics [1] |
Other names | trans-2-phenylcyclopropylamine |
AHFS/Drugs.com | Monograph |
MedlinePlus | a682088 |
Pregnancy category |
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Routes of administration | Oral |
ATC code | |
Legal status | |
Legal status | |
Pharmacokinetic data | |
Bioavailability | 50% [4] |
Metabolism | Liver [5] [6] |
Elimination half-life | 2.5 hours [4] |
Excretion | Urine, Feces [4] |
Identifiers | |
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CAS Number | |
PubChem CID | |
DrugBank | |
ChemSpider | |
UNII | |
KEGG | |
ChEBI | |
ChEMBL | |
ECHA InfoCard | 100.005.312 |
Chemical and physical data | |
Formula | C9H11N |
Molar mass | 133.194 g·mol−1 |
3D model (JSmol) | |
Chirality | Racemic mixture |
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Tranylcypromine, sold under the brand name Parnate among others, [1] is a monoamine oxidase inhibitor (MAOI). [4] [7] More specifically, tranylcypromine acts as nonselective and irreversible inhibitor of the enzyme monoamine oxidase (MAO). [4] [7] It is used as an antidepressant and anxiolytic agent in the clinical treatment of mood and anxiety disorders, respectively.
Tranylcypromine is a cyclopropylamine formed pro forma from the cyclization of amphetamine's side chain; therefore, it is classified as a substituted amphetamine.
Tranylcypromine is used to treat major depressive disorder, including atypical depression, especially when there is an anxiety component, typically as a second-line treatment. [8] It is also used in depression that is not responsive to reuptake inhibitor antidepressants, such as the SSRIs, TCAs, or bupropion. [9] In addition to being a recognized treatment for major depressive disorder, tranylcypromine has been demonstrated to be effective in treating obsessive compulsive disorder [10] [11] [12] and panic disorder. [13] [14]
Systematic reviews and meta-analyses have reported that tranylcypromine is significantly more effective in the treatment of depression than placebo and has efficacy over placebo similar to that of other antidepressants such as tricyclic antidepressants. [15] [16]
Contraindications include: [8] [9] [17]
Tyramine is a biogenic amine produced as a (generally undesirable) byproduct during the fermentation of certain tyrosine-rich foods. It is rapidly metabolized by MAO-A in those not taking MAO-inhibiting drugs. Individuals sensitive to tyramine-induced hypertension may experience an uncomfortable, yet fleeting, increase in blood pressure after ingesting relatively small amounts of tyramine. [18] [17] [19]
Advances in food safety standards in most nations, as well as the widespread use of starter-cultures shown to result in undetectable to low levels of tyramine in fermented products has rendered concerns of serious hypertensive crises rare in those consuming a modern diet. [20] [19] Those treated with MAOIs should still exercise caution, particularly at home, if it is unclear whether food has been properly refrigerated. Since tyramine-producing microbes also produce compounds to which humans have a natural aversion, disposal of any questionable food—particularly meats—should be sufficient to avoid hypertensive crises.
Incidence of adverse effects [15]
Very common (>10% incidence) adverse effects include:
Common (1-10% incidence) adverse effects include:
Other (unknown incidence) adverse effects include:
Of note, there has not been found to be a correlation between sex and age below 65 regarding incidence of adverse effects. [15]
Tranylcypromine is not associated with weight gain and has a low risk for hepatotoxicity compared to the hydrazine MAOIs. [15] [9]
It is generally recommended that MAOIs be discontinued prior to anesthesia; however, this creates a risk of recurrent depression. In a retrospective observational cohort study, patients on tranylcypromine undergoing general anesthesia had a lower incidence of intraoperative hypotension, while there was no difference between patients not taking an MAOI regarding intraoperative incidence of bradycardia, tachycardia, or hypertension. [21] The use of indirect sympathomimetic drugs or drugs affecting serotonin reuptake, such as meperidine or dextromethorphan poses a risk for hypertension and serotonin syndrome respectively; alternative agents are recommended. [22] [23] Other studies have come to similar conclusions. [15] Pharmacokinetic interactions with anesthetics are unlikely, given that tranylcypromine is a high-affinity substrate for CYP2A6 and does not inhibit CYP enzymes at therapeutic concentrations. [18]
Tranylcypromine abuse has been reported at doses ranging from 120 to 600 mg per day. [8] [24] [15] It is thought that higher doses have more amphetamine-like effects and abuse is promoted by the fast onset and short half-life of tranylcypromine. [15]
Cases of suicidal ideation and suicidal behaviours have been reported during tranylcypromine therapy or early after treatment discontinuation. [8]
Symptoms of tranylcypromine overdose are generally more intense manifestations of its usual effects. [8]
In addition to contraindicated concomitant medications, tranylcypromine inhibits CYP2A6, which may reduce the metabolism and increase the toxicity of substrates of this enzyme, such as: [17]
Norepinephrine reuptake inhibitors prevent neuronal uptake of tyramine and may reduce its pressor effects. [17]
Tranylcypromine acts as a nonselective and irreversible inhibitor of monoamine oxidase. [4] Regarding the isoforms of monoamine oxidase, it shows slight preference for the MAOB isoenzyme over MAOA. [18] This leads to an increase in the availability of monoamines, such as serotonin, norepinephrine, and dopamine, epinephrine as well as a marked increase in the availability of trace amines, such as tryptamine, octopamine, and phenethylamine. [18] [17] The clinical relevance of increased trace amine availability is unclear.
It may also act as a norepinephrine reuptake inhibitor at higher therapeutic doses. [18] Compared to amphetamine, tranylcypromine shows low potency as a dopamine releasing agent, with even weaker potency for norepinephrine and serotonin release. [18] [17]
Tranylcypromine has also been shown to inhibit the histone demethylase, BHC110/LSD1. Tranylcypromine inhibits this enzyme with an IC50 < 2 μM, thus acting as a small molecule inhibitor of histone demethylation with an effect to derepress the transcriptional activity of BHC110/LSD1 target genes. [25] The clinical relevance of this effect is unknown.
Tranylcypromine has been found to inhibit CYP46A1 at nanomolar concentrations. [26] The clinical relevance of this effect is unknown.
Tranylcypromine reaches its maximum concentration (tmax) within 1–2 hours. [18] After a 20 mg dose, plasma concentrations reach at most 50-200 ng/mL. [18] While its half-life is only about 2 hours, its pharmacodynamic effects last several days to weeks due to irreversible inhibition of MAO. [18]
Metabolites of tranylcypromine include 4-hydroxytranylcypromine, N-acetyltranylcypromine, and N-acetyl-4-hydroxytranylcypromine, which are less potent MAO inhibitors than tranylcypromine itself. [18] Amphetamine was once thought to be a metabolite of tranylcypromine, but has not been shown to be. [18] [28] [17]
Tranylcypromine inhibits CYP2A6 at therapeutic concentrations. [17]
Tranylcypromine was originally developed as an analog of amphetamine. [4] [18] Although it was first synthesized in 1948, [30] its MAOI action was not discovered until 1959. Precisely because tranylcypromine was not, like isoniazid and iproniazid, a hydrazine derivative, its clinical interest increased enormously, as it was thought it might have a more acceptable therapeutic index than previous MAOIs. [31]
The drug was introduced by Smith, Kline and French in the United Kingdom in 1960, and approved in the United States in 1961. [32] It was withdrawn from the market in February 1964 due to a number of patient deaths involving hypertensive crises with intracranial bleeding. However, it was reintroduced later that year with more limited indications and specific warnings of the risks. [33] [18] [17]
Tranylcypromine is known to inhibit LSD1, an enzyme that selectively demethylates two lysines found on histone H3. [25] [18] [34] Genes promoted downstream of LSD1 are involved in cancer cell growth and metastasis, and several tumor cells express high levels of LSD1. [34] Tranylcypromine analogues with more potent and selective LSD1 inhibitory activity are being researched in the potential treatment of cancers. [34] [35]
Tranylcypromine may have neuroprotective properties applicable to the treatment of Parkinson's disease, similar to the MAO-B inhibitors selegiline and rasagiline. [36] [9] As of 2017, only one clinical trial in Parkinsonian patients has been conducted, which found some improvement initially and only slight worsening of symptoms after a 1.5 year followup. [9]
Antidepressants are a class of medications used to treat major depressive disorder, anxiety disorders, chronic pain, and addiction.
An anxiolytic is a medication or other intervention that reduces anxiety. This effect is in contrast to anxiogenic agents which increase anxiety. Anxiolytic medications are used for the treatment of anxiety disorders and their related psychological and physical symptoms.
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.
Monoamine oxidases (MAO) are a family of enzymes that catalyze the oxidation of monoamines, employing oxygen to clip off their amine group. They are found bound to the outer membrane of mitochondria in most cell types of the body. The first such enzyme was discovered in 1928 by Mary Bernheim in the liver and was named tyramine oxidase. The MAOs belong to the protein family of flavin-containing amine oxidoreductases.
A psychiatric or psychotropic medication is a psychoactive drug taken to exert an effect on the chemical makeup of the brain and nervous system. Thus, these medications are used to treat mental illnesses. These medications are typically made of synthetic chemical compounds and are usually prescribed in psychiatric settings, potentially involuntarily during commitment. Since the mid-20th century, such medications have been leading treatments for a broad range of mental disorders and have decreased the need for long-term hospitalization, thereby lowering the cost of mental health care. The recidivism or rehospitalization of the mentally ill is at a high rate in many countries, and the reasons for the relapses are under research.
Monoamine neurotransmitters are neurotransmitters and neuromodulators that contain one amino group connected to an aromatic ring by a two-carbon chain (such as -CH2-CH2-). Examples are dopamine, norepinephrine and serotonin.
Phenelzine, sold under the brand name Nardil, among others, is a non-selective and irreversible monoamine oxidase inhibitor (MAOI) of the hydrazine class which is primarily used as an antidepressant and anxiolytic. Along with tranylcypromine and isocarboxazid, phenelzine is one of the few non-selective and irreversible MAOIs still in widespread clinical use.
Tyramine, also known under several other names, is a naturally occurring trace amine derived from the amino acid tyrosine. Tyramine acts as a catecholamine releasing agent. Notably, it is unable to cross the blood-brain barrier, resulting in only non-psychoactive peripheral sympathomimetic effects following ingestion. A hypertensive crisis can result, however, from ingestion of tyramine-rich foods in conjunction with the use of monoamine oxidase inhibitors (MAOIs).
Serotonin–norepinephrine reuptake inhibitors (SNRIs) are a class of antidepressant medications used to treat major depressive disorder (MDD), anxiety disorders, social phobia, chronic neuropathic pain, fibromyalgia syndrome (FMS), and menopausal symptoms. Off-label uses include treatments for attention-deficit hyperactivity disorder (ADHD), obsessive–compulsive disorder (OCD), and migraine prevention. SNRIs are monoamine reuptake inhibitors; specifically, they inhibit the reuptake of serotonin and norepinephrine. These neurotransmitters are thought to play an important role in mood regulation. SNRIs can be contrasted with the selective serotonin reuptake inhibitors (SSRIs) and norepinephrine reuptake inhibitors (NRIs), which act upon single neurotransmitters.
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. 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.
Isocarboxazid is a non-selective, irreversible monoamine oxidase inhibitor (MAOI) of the hydrazine class used as an antidepressant. Along with phenelzine and tranylcypromine, it is one of only three classical MAOIs still available for clinical use in the treatment of psychiatric disorders in the United States, though it is not as commonly employed in comparison to the others.
Dopaminergic means "related to dopamine" (literally, "working on dopamine"), dopamine being a common neurotransmitter. Dopaminergic substances or actions increase dopamine-related activity in the brain. Dopaminergic brain pathways facilitate dopamine-related activity. For example, certain proteins such as the dopamine transporter (DAT), vesicular monoamine transporter 2 (VMAT2), and dopamine receptors can be classified as dopaminergic, and neurons that synthesize or contain dopamine and synapses with dopamine receptors in them may also be labeled as dopaminergic. Enzymes that regulate the biosynthesis or metabolism of dopamine such as aromatic L-amino acid decarboxylase or DOPA decarboxylase, monoamine oxidase (MAO), and catechol O-methyl transferase (COMT) may be referred to as dopaminergic as well. Also, any endogenous or exogenous chemical substance that acts to affect dopamine receptors or dopamine release through indirect actions (for example, on neurons that synapse onto neurons that release dopamine or express dopamine receptors) can also be said to have dopaminergic effects, two prominent examples being opioids, which enhance dopamine release indirectly in the reward pathways, and some substituted amphetamines, which enhance dopamine release directly by binding to and inhibiting VMAT2.
Milnacipran is a serotonin–norepinephrine reuptake inhibitor (SNRI) used in the clinical treatment of fibromyalgia. It is not approved for the clinical treatment of major depressive disorder in the US, but it is in other countries.
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.
Iproniazid is a non-selective, irreversible monoamine oxidase inhibitor (MAOI) of the hydrazine class. It is a xenobiotic that was originally designed to treat tuberculosis, but was later most prominently used as an antidepressant drug. However, it was withdrawn from the market because of its hepatotoxicity. The medical use of iproniazid was discontinued in most of the world in the 1960s, but remained in use in France until its discontinuation in 2015.
Rasagiline is an irreversible inhibitor of monoamine oxidase-B used as a monotherapy to treat symptoms in early Parkinson's disease or as an adjunct therapy in more advanced cases.
A serotonin–norepinephrine–dopamine reuptake inhibitor (SNDRI), also known as a triple reuptake inhibitor (TRI), is a type of drug that acts as a combined reuptake inhibitor of the monoamine neurotransmitters serotonin, norepinephrine, and dopamine. It does this by concomitantly inhibiting the serotonin transporter (SERT), norepinephrine transporter (NET), and dopamine transporter (DAT), respectively. Inhibition of the reuptake of these neurotransmitters increases their extracellular concentrations and, therefore, results in an increase in serotonergic, adrenergic, and dopaminergic neurotransmission. The naturally-occurring and potent SNDRI cocaine is widely used recreationally and often illegally for the euphoric effects it produces.
Monoamine oxidase B, also known as MAO-B, is an enzyme that in humans is encoded by the MAOB gene.
An adrenergic storm is a sudden and dramatic increase in serum levels of the catecholamines adrenaline and noradrenaline, with a less significant increase in dopamine transmission. It is a life-threatening condition because of extreme tachycardia and hypertension, and is especially dire for those with prior heart problems. If treatment is prompt, prognosis is good; typically large amounts of diazepam or other benzodiazepines are administered alongside beta blockers. Beta blockers are contraindicated in some patients, so other anti-hypertensive medication such as clonidine may be used. Antipsychotics are also used to treat the most severe psychiatric reactions such as psychosis, paranoia or terror, after their use was formerly discouraged because of their potential to prolong the QT interval; however, more recent research performed since 2019 has revealed that this and other severe side effects are rare and their occurrence does not warrant banning antipsychotics from the treatment of adrenergic crises for which they can be extremely useful.
Selective norepinephrine reuptake inhibitors (sNRIs) are a class of drugs that have been marketed as antidepressants and are used for various mental disorders, mainly depression and attention-deficit hyperactivity disorder (ADHD). The norepinephrine transporter (NET) serves as the fundamental mechanism for the inactivation of noradrenergic signaling because of the NET termination in the reuptake of norepinephrine (NE). The selectivity and mechanism of action for the NRI drugs remain mostly unresolved and, to date, only a limited number of NRI-selective inhibitors are available. The first commercially available selective NRI was the drug reboxetine (Edronax), developed as a first-line therapy for major depressive disorder. Atomoxetine (Strattera) is another potent and selective NRI which is also effective and well tolerated for the treatment of ADHD in adults; it may also be a new treatment option for adults with ADHD, particularly for those patients at risk of substance abuse.