phenelzine 

Action and Spectrum

Actions and Spectrum: 

The actions and spectrum of phenelzine include: 

• Antidepressant effects: phenelzine is used primarily as an antidepressant medication. It has been found to be effective in treating depression but has not responded to other antidepressants. The antidepressant effects of phenelzine are thought to be due to its ability to increase the levels of monoamine neurotransmitters in the brain. 
• Anxiolytic effects: phenelzine has also been found to have anxiolytic effects, meaning it can reduce anxiety. This is thought to be due to its effects on neurotransmitters such as serotonin and norepinephrine levels in the brain. 
• Hypotensive effects: phenelzine can cause a drop in blood pressure, which can be desirable in some patients with hypertension. However, this effect can also be problematic in some patients, mainly if they are already hypotensive. 
• Interactions with other medications and foods: phenelzine can interact with a wide range of medications and foods, including other antidepressants, certain pain medications, and foods containing high levels of tyramine. These interactions can be severe and potentially life-threatening, so patients taking phenelzine need to be closely monitored. 
• Limited spectrum of activity: phenelzine is effective in treating depression, but it has a limited spectrum of activity and is ineffective in treating other psychiatric conditions such as anxiety disorders, bipolar disorder, or schizophrenia. 

Drug Interaction

Adverse Reaction

Frequency not defined 

Orthostatic hypotension 

Asthenia 

Drowsiness 

Fatigue 

Dizziness 

Headache 

Hyperreflexia 

Sleep disturbance 

Tremor 

Constipation 

Weight gain  

Somnolence 

Weakness 

Dry mouth 

Black Box Warning

Black Box Warning: 

phenelzine increases the risk of suicidal thoughts and alters behavior in young adults. The drug is not meant for pediatrics. 

Contraindication / Caution

Contraindication/Caution: 

There are several contraindications and cautions associated with the use of phenelzine, including: 

Contraindications: 

• Do not use phenelzine if you have a history of hypersensitivity to phenelzine or its components. 
• Do not use phenelzine if you are taking or have recently taken medications such as other MAOIs, certain pain medications, or certain psychiatric medications, as these can interact with phenelzine and cause a severe reaction called serotonin syndrome. 
• Do not use phenelzine if you have a history of pheochromocytoma (a type of tumor), as phenelzine can cause a dangerous increase in blood pressure in these patients. 

Caution: 

• Use phenelzine with caution in patients with a history of cardiovascular disease, as it can cause hypotension (low blood pressure) and other cardiovascular effects. 
• Use phenelzine with caution in patients with a history of liver or kidney disease, as it can affect the metabolism and elimination of the medication. 
• Use phenelzine with caution in elderly patients, as they may be more sensitive to the effects of the medication. 
• Use phenelzine with caution in patients with a history of seizures, as it can lower the seizure threshold and increase the risk. 

Pregnancy / Lactation

Pregnancy consideration:  

No data available for utilization in pregnant women 

Breastfeeding warnings:  

Drug distribution in breast milk is unknown, so use the drug cautiously during lactation. 

Pregnancy category: 

• Category A: Satisfactory and well-controlled studies show no risk to the fetus in the first or later trimester. 
• Category B: No evidence of risk to the fetus is found in animal reproduction studies, and there are not enough studies on pregnant women. 
• Category C: Adverse effects on the fetus found with evidence in animal reproduction studies and no adequate evidence for a human product; Pregnant women must take care of the potential risks. 
• Category D: There is adequate data with sufficient evidence of human fetal risk from various platforms. However, despite potential dangers may be used only in emergencies for potential benefits. 
• Category X: Drugs listed in this category outweigh the risks over benefits. The drug is not for pregnant women. 
• Category N: No data for the drug under this category is available. 

Pharmacology

Pharmacology: 

The pharmacology of phenelzine involves several mechanisms of action, including: 

• Inhibition of monoamine oxidase: phenelzine inhibits the activity of the enzyme monoamine oxidase (MAO), which is responsible for breaking down neurotransmitters such as serotonin, norepinephrine, and dopamine. By inhibiting the activity of MAO, phenelzine increases the levels of these neurotransmitters in the brain, which can lead to improvements in mood and other depressive symptoms. 
• Increased availability of neurotransmitters: By increasing the levels of neurotransmitters such as serotonin, norepinephrine, and dopamine, phenelzine can enhance their availability in the synapse (the junction between neurons), where they can bind to receptors and transmit signals between neurons. 
• Downregulation of adrenergic and serotonergic receptors: Chronic administration of phenelzine can lead to downregulation (reduction in number) of adrenergic and serotonergic receptors in the brain, which may contribute to its therapeutic effects. 
• Inhibition of other enzymes: phenelzine can also inhibit the activity of other enzymes in the body, such as catechol-O-methyltransferase (COMT), which is involved in the breakdown of dopamine. 

Pharmacodynamics: 

The pharmacodynamics of phenelzine involves several mechanisms of action that contribute to its therapeutic effects: 

• Inhibition of monoamine oxidase (MAO): phenelzine irreversibly inhibits the activity of MAO, an enzyme responsible for breaking down neurotransmitters such as serotonin, norepinephrine, and dopamine. By inhibiting the activity of MAO, phenelzine increases the levels of these neurotransmitters in the brain, which can lead to improvements in mood and other depressive symptoms. 
• Increased availability of neurotransmitters: By inhibiting the breakdown of neurotransmitters, phenelzine can increase their availability in the synapse (the junction between neurons), where they can bind to receptors and transmit signals between neurons. 
• Downregulation of adrenergic and serotonergic receptors: Chronic administration of phenelzine can lead to downregulation (reduction in number) of adrenergic and serotonergic receptors in the brain, which may contribute to its therapeutic effects. 
• Inhibition of other enzymes: phenelzine can also inhibit the activity of other enzymes in the body, such as catechol-O-methyltransferase (COMT), which is involved in the breakdown of dopamine. 
• Modulation of the neuroendocrine system: phenelzine can also modulate the neuroendocrine system by affecting the release and metabolism of hormones such as cortisol and thyroid hormones. 

Pharmacokinetics: 

Absorption 

The Peak Plasma concentration is achieved in 43 minutes 

Distribution 

The onset of action takes place in 2-4 weeks 

Duration of action is 2 weeks 

Metabolism 

Metabolism takes place by MAO  

Metabolites formed are parahydroxyphenylacetic acid 

& phenylacetic acid  

Elimination and Excretion 

The elimination half-life is 11.6 hours 

The drug is excreted in urine 

Adminstartion

Administration: 

phenelzine is usually administered orally as a tablet or capsule. The typical starting dose for adults is 15 mg, taken two to three times per day. The dose can be gradually increased, as needed and tolerated, up to a maximum of 90 mg daily. 

phenelzine should be taken with food to improve its absorption and reduce the risk of gastrointestinal side effects. Following the dosing schedule and instructions the prescribing healthcare provider provides is essential. 

Patient Information Leaflet

Patient information leaflet 

Generic Name:  phenelzine 

Pronounced: FEN-el-zeen 

Why do we use phenelzine? 

phenelzine is a medication used to treat major depressive disorder (MDD) and other mood disorders. It belongs to a class of medications known as monoamine oxidase inhibitors (MAOIs).