BMA Concise Guide to Medicine & Drugs

Prochlorperazine

Brand names Buccastem, Stemetil

Used in the following combined preparations None

QUICK REFERENCE

Drug group Phenothiazine antipsychotic drug and anti-emetic drug

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes (most preparations)

Available as generic Yes

GENERAL INFORMATION

Prochlorperazine was introduced in the late 1950s and belongs to a group of drugs called the phenothiazines, which act on the central nervous system.

In small doses, prochlorperazine controls nausea and vomiting, especially when they occur as the side effects of medical treatment by drugs or radiation, or of anaesthesia. It is available over the counter for nausea and vomiting associated with migraine. The drug is also used to treat the nausea that occurs with inner-ear disorders such as vertigo. In large doses, it is sometimes used as an antipsychotic to reduce aggressiveness and suppress abnormal behaviour. It thus minimizes and controls the abnormal behaviour of schizophrenia, mania, and other mental disorders. Prochlorperazine does not cure any of these diseases, but it helps to relieve symptoms.

INFORMATION FOR USERS

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

How taken/used Tablets, buccal tablets, effervescent granules, liquid, injection.

Frequency and timing of doses 2–3 x daily.

Adult dosage range Nausea and vomiting 20mg initially, then 5–10mg per dose (tablets); 12.5mg per dose (injection). Mental illness 25–100mg daily. Larger doses may be given.

Onset of effect Within 60 minutes (by mouth); 10–20 minutes (by injection).

Duration of action 3–6 hours.

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children. Protect from light.

Missed dose Take as soon as you remember. If your next dose is due within 2 hours, take a single dose now and skip the next.

Stopping the drug Do not stop the drug without consulting your doctor; symptoms may recur.

Exceeding the dose An occasional unintentional extra dose is unlikely to be a cause for concern. Large overdoses may cause unusual drowsiness and may affect the heart. Notify your doctor.

POSSIBLE ADVERSE EFFECTS

Prochlorperazine has a strong anticholinergic effect that can cause a variety of minor symptoms, such as dry mouth and constipation, which often become less marked with time. The most significant adverse effect with high doses is tremor and muscle rigidity of the face and limbs (parkinsonism) caused by changes in the balance of chemicals in the brain. If parkinsonism occurs, or if you experience dizziness and fainting with the drug, consult your doctor. Other common adverse effects include drowsiness and lethargy; discuss with your doctor if these are severe. Rarely, a rash or jaundice may occur; if so, you should stop taking the drug and consult your doctor.

INTERACTIONS

Sedatives All drugs with a sedative effect are likely to increase the sedative effects of prochlorperazine.

Drugs for Parkinson’s disease Prochlorperazine may block the beneficial effect of these drugs.

Anticholinergic drugs Prochlorperazine may increase the side effects of these drugs.

Antihypertensive drugs Prochlorperazine can increase the effects of these drugs, especially doxazosin.

SPECIAL PRECAUTIONS

Be sure to tell your doctor if:

· You have heart problems.

· You have liver or kidney problems.

· You have had epileptic seizures.

· You have Parkinson’s disease.

· You have dementia.

· You have prostate problems.

· You have glaucoma.

· You are taking other medicines.

Pregnancy Safety in pregnancy not established. Discuss with your doctor.

Breast-feeding The drug passes into the breast milk and may affect the baby. Discuss with your doctor.

Infants and children Not recommended in infants weighing less than 10kg and young children. Reduced dose necessary in older children due to increased risk of adverse effects.

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

Driving and hazardous work Avoid such activities until you have learned how prochlorperazine affects you because it can cause drowsiness and reduced alertness.

Alcohol Avoid. Alcohol may increase and prolong the sedative effects of this drug.

PROLONGED USE

Use of this drug for more than a few months may lead to the development of involuntary, potentially irreversible, eye, mouth, and tongue movements (tardive dyskinesia). Occasionally, jaundice may occur.

Monitoring Periodic blood tests may be performed.