Phenelzine (Nardil)
Phenelzine is an older, non-selective mono amine oxidase inhibitor. It has an irreversible effect on MAO, so its effect lasts for months.
Phenelzine is rarely used anymore; it is estimated that between 75,000 and 85,000 people world-wide take the drug. Although the patent has expired for Nardil, generic brands haven't emerged because the market is too small.
The Bottom Line: What You Really Need to Know
- Phenelzine (Nardil) is used to treat anxiety, atypical depression, bulimia and social anxiety.
- The usual dose of phenelzine is 15 mg three times a day, with an additional 15 mg dose added in a week or so if necessary. Be sure to take it exactly as your doctor directs.
- Phenelzine interacts with many different medications. Make sure you tell your physician and pharmacist about all medications that you take, including herbal remedies and teas, over the counter medications, homeopathic and alternative treatments, vitamins, supplements and medications you only take occasionally.
- Phenelzine has a dangerous interaction with the amine acid tyramine, which is found in many foods. It is important to follow a special low tyramine diet while taking it.
- If you have surgery, make sure your surgeon knows you take phenelzine. It can interact with anesthetics.
- It may take four weeks or more before you start feeling better.
- Talk to your doctor before you stop taking phenelzine. Your dose may need to be tapered down slowly to prevent uncomfortable withdrawal symptoms.
- Most people experience a few mild side effects, like dizziness, headache or fatigue, when they begin taking phenelzine. They usually go away with time.
- If you get dizzy or faint when you stand up suddenly, get up slowly. Move to a sitting position for a moment before standing.
- If you experience loss of interest in sex or diminished sexual ability, talk to your doctor about it.
- Have a friend or family member check in with you every day for the first few weeks that you take phenelzine. Ask him or her to help you monitor your condition for:
- Worsening depression
- Restlessness, irritability, agitation, hostility or aggression
- Unusual thoughts or thoughts of suicide
- Report any serious or unusual side effects to your doctor.
Uses of phenelzine
Phenelzine is approved for the treatment of anxiety, atypical depression, bulimia, depression that does not respond to other methods of treatment and social anxiety disorder. Phenelzine is rarely used as a first-line drug; rather it is reserved for instances when other medications don't work.
Dosage and instructions
Phenelzine therapy is started at 15 mg three times a day and rapidly increased to a total of 60 mg/day. The maximum recommended dose is 90 mg/day. It can take up to four weeks to get the full effect of phenelzine.
Once the maximum benefit has been obtained, the dose of phenelzine is slowly reduced to the lowest dose that maintains the benefit. This can be as low as 15 mg once a day. Therapy continues at that dose for as long as needed.
How phenelzine works
Phenelzine inhibits the function of mono amine oxidase, a complex enzyme system, throughout the body. MAO has many functions, one of which is regulation of various neurochemicals that are implicated in depression and anxiety.
Phenelzine is a non-selective MAOI and it inhibits both MAO-A and MAO-B.
The half-life (time it remains in your body) of phenelzine is short, but its effect on MAO is irreversible. It takes your body months to create new MAO, so the effect of phenelzine lasts for a long time.
Phenelzine is broken down in the liver and removed from the body through the urine.
Side Effects
Side effects with phenelzine are usually mild to moderate in severity and often resolve over time or with a reduction in dose. The most common side effects are:
- Orthostatic hypotension (feeling lightheaded or fainting when you stand up suddenly)
- Dizziness
- Headache
- Fatigue
- Insomnia
- Sexual difficulties
- Tremors and twitching
- Dry mouth, nausea, upset stomach, diarrhea or constipation
Interactions with other medications and food
Phenelzine interacts with many medications and with foods containing the amino acid tyramine. Tyramine-containing foods have usually been aged-things like wine, cheese, aged meats, sauerkraut, chocolate and caffeine. If you are taking phenelzine, make sure you have a complete list of foods you need to avoid and do avoid those foods. Eating tyramine-containing foods while taking phenelzine can cause a hypertensive crisis and result in a stroke or heart attack.
There is a long list of medications that have serious and potentially fatal interactions with phenelzine. Some of them are:
- Serotinergic medications-SSRI, SNRI, tricyclic and other antidepressants, tryptophan and St. John's wort. Interaction can produce high fever, muscle rigidity and jerking, seizures and death.
- Sympathomimetic medications-medications similar to epinephrine and norepinephrine-includes amphetamines, cocaine, phenylalanine, methyldopa. Interaction can produce hypertensive crisis-extremely high blood pressure, headache, chest pain, sweating, fever-can lead to heart attack, stroke or death.
- Pain medications-certain narcotics (especially meperdine (Demerol)), dextromethorphan (cough medicine), alcohol. Reaction produces agitation and overexcitability, delirium, fever, seizures, circulatory collapse, shock and death.
- Buspirone can interact with phenelzine and cause high blood pressure.
- Guanethedine is contraindicated with phenelzine.
Warnings, precautions and contraindications
Suicide risk: It is believed that all antidepressants can increase the risk of suicide, especially in the first weeks or months of therapy. Anyone who starts taking any new antidepressant should be closely monitored for signs of worsening depression and thoughts of harming self or others.
Medication interactions: Phenelzine can produce serious and even fatal interactions with many foods and medications. Make sure you have a complete list of foods that you should avoid. Also, make sure your doctor and pharmacist know about all of the medications you take, even if they are over-the-counter and you only take them occasionally. Make sure to include all vitamins and supplements on your medication list.
Activation of mania: Phenelzine can activate manic episodes in people with bipolar disease and can cause rapid cycling between mania and depression. Psychosis, self-destructive behavior and violence can occur. Depressed people should be screened for bipolar disease before beginning treatment with phenelzine.
Controversy
In 2003, Pfizer reformulated the inactive ingredients in Nardil; users noticed a change in the effectiveness of the drug and began to experience side effects and loss of effectiveness of the drug. There have been complaints that the change was made to cut expenses in manufacturing the drug and that the manufacturer has been unresponsive to the needs of the customers.
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