BMA Concise Guide to Medicine & Drugs

Phenelzine

Brand name Nardil

Used in the following combined preparations None

QUICK REFERENCE

Drug group Antidepressant drug

Overdose danger rating High

Dependence rating Low

Prescription needed Yes

Available as generic No

GENERAL INFORMATION

Phenelzine is a monoamine oxidase inhibitor (MAOI) antidepressant drug. It works by blocking the enzyme monoamine oxidase, which normally breaks down neurotransmitters (mainly serotonin and noradrenaline) in the brain and elsewhere in the body. Low levels of these neurotransmitters in the brain are a causative factor in depression, and the effect of MAOIs is to increase their levels. Due to its potentially serious adverse effects and interactions with other drugs and foodstuffs, phenelzine’s use is reserved for people for whom other antidepressants have been ineffective or whose depression occurs together with anxiety, phobia, hysteria, or hypochondria.

INFORMATION FOR USERS

Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets.

Frequency and timing of doses Initially, 3–4 x daily. After satisfactory response has been achieved, dose may be gradually reduced to once daily or once every other day.

Adult dosage range 15–60mg daily. Patients receiving hospital treatment may be given up to 90mg daily.

Onset of effect Effectiveness may not be felt for up to 4 weeks.

Duration of action Antidepressant effect may last for some months or longer following prolonged use.

Diet advice Avoid foods containing tyramine, such as cheese, meat or yeast extracts, fermented soya bean extracts, pickled herrings, hung game, and alcoholic drinks; low-alcohol drinks should also be avoided. Discuss with your doctor.

Storage Store between 2–8°C in a refrigerator. Keep out of the reach of children.

Missed dose Take as soon as you remember. If your next scheduled dose is due within 12 hours, skip the missed dose and take the next dose as scheduled.

Stopping the drug Do not stop the drug without consulting your doctor. Stopping abruptly may cause withdrawal symptoms and a recurrence of depression.

OVERDOSE ACTION

Seek immediate medical advice in all cases. An overdose may be fatal. Take emergency action if breathing problems or loss of consciousness occur.

POSSIBLE ADVERSE EFFECTS

Side effects are common with phenelzine and some are potentially serious. Common ones include dizziness, drowsiness, nausea, vomiting, constipation, sleep disturbance, blurred vision, and twitching or jerking movements. Discuss with your doctor if any of these are severe. More rarely, a rash, fever, tightness in the muscles, jaundice, or suicidal thoughts may occur. If the rash is severe, contact your doctor promptly. If any of the other rarer symptoms occur, stop taking the drug and consult your doctor immediately.

INTERACTIONS

General note Phenelzine interacts with a wide range of drugs, and some interactions may be dangerous. Consult your doctor before taking any other medication.

Tyramine Phenelzine interacts with tyramine-containing food and drinks (see Diet advice) to cause a potentially life-threatening rise in blood pressure.

SPECIAL PRECAUTIONS

Be sure to tell your doctor if:

· You have high blood pressure or heart disease.

· You have had a stroke.

· You have liver disease.

· You have a blood disorder.

· You have diabetes.

· You have epilepsy.

· You have porphyria.

· You have phaeochromocytoma.

· You are taking any other medicines, including over-the-counter cough or cold remedies or illicit drugs.

Pregnancy Safety not established. Discuss with your doctor.

Breast-feeding Safety not established. Discuss with your doctor.

Infants and children Not recommended for children under 16 years old.

Over 60 Increased likelihood of adverse effects. Reduced dose may be necessary.

Driving and hazardous work Avoid such activities until you have learned how phenelzine affects you because the drug may cause dizziness, drowsiness, and blurred vision.

Alcohol Avoid. Many alcoholic drinks contain tyramine, which may interact with phenelzine. The drug also enhances the effects of alcohol.

Surgery and general anaesthetics Due to a potentially dangerous interaction with general anaesthetics, phenelzine should be withdrawn 2 weeks before any surgery or dentistry requiring general anaesthesia. Discuss with your doctor or dentist.

PROLONGED USE

Withdrawal symptoms may occur if the drug is not stopped gradually over at least 4 weeks. Such symptoms include nausea, vomiting, malaise, nightmares, and agitation.