BMA Concise Guide to Medicine & Drugs

Pizotifen

Brand name Sanomigran

Used in the following combined preparations None

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Drug group Drug for migraine

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes

Available as generic Yes

GENERAL INFORMATION

Pizotifen is an antihistamine drug with a chemical structure similar to that of the tricyclic antidepressants; it also has similar anticholinergic effects. This drug is prescribed for the prevention of migraine headaches in people who suffer frequent, disabling attacks. It is not effective in relieving migraine attacks once they have started. Pizotifen is thought to work by blocking the chemicals (histamine and serotonin) that act on blood vessels in the brain.

The main disadvantage of prolonged use of pizotifen is that it stimulates the appetite and, as a result, often causes weight gain. It is usually prescribed only for people in whom other measures for migraine prevention, such as avoidance of trigger factors, have failed.

The sweetener used in the liquid medication is hydrogenated glucose syrup, and this may affect levels of blood sugar.

INFORMATION FOR USERS

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

How taken/used Tablets, liquid.

Frequency and timing of doses Once a day (at night) or 3 x daily.

Adult dosage range 1.5–4.5mg daily. Maximum single dose 3mg.

Onset of effect Full beneficial effects may not be felt for several days.

Duration of action Effects of this drug may last for several weeks.

Diet advice Migraine sufferers may be advised to avoid foods that trigger headaches in their case.

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 4 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 cause problems. Large overdoses may cause drowsiness, nausea, palpitations, seizures, and coma. Notify your doctor.

POSSIBLE ADVERSE EFFECTS

Drowsiness is a common adverse effect that can often be minimized by starting with a low dose and then gradually increasing it. Increased appetite, weight gain, fatigue, nausea, and dizziness are also common. More rarely, pizotifen may cause muscle pains, dry mouth, blurred vision, anxiety, and depression. Consult your doctor if you experience anxiety or depression or if any of the other adverse effects are severe.

INTERACTIONS

Anticholinergic drugs The weak anticholinergic effects of pizotifen may be increased by other anticholinergic drugs, including tricyclic antidepressants.

Antihypertensive drugs The blood pressure-lowering effects of guanethidine and debrisoquine are reduced by pizotifen.

Sedatives All drugs that have a sedative effect on the central nervous system are likely to increase the sedative properties of pizotifen. These include sleeping drugs, anti-anxiety drugs, opioid analgesics, and antihistamines.

SPECIAL PRECAUTIONS

Be sure to tell your doctor if:

· You have a long-term kidney problem.

· You have glaucoma.

· You have urinary retention.

· You have prostate problems.

· You have galactose intolerance.

· You are taking other medicines.

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

Breast-feeding The drug passes into the breast milk, but at normal doses adverse effects on the baby are unlikely. Discuss with your doctor.

Infants and children Reduced dose usually necessary. Not recommended under 7 years.

Over 60 No special problems.

Driving and hazardous work Avoid such activities until you have learned how pizotifen affects you because the drug can cause drowsiness and blurred vision.

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

PROLONGED USE

Pizotifen often causes weight gain during long-term use. Treatment is usually reviewed every 6 months.