Pizotifen

Antigrain is indicated as prophylactic treatment of vascular headache of migraine type such as classical migraine, common migraine and cluster headache. It is not effective in relieving migraine attacks once in progress.

Pizotifen works by inhibiting the peripheral actions of serotonin and histamine in increasing the membrane permeability of cranial vessels and transudation of plasmakinin, while altering pain thresholds in migraines. By blocking 5-HT receptors, pizotifen attenuates the signalling of serotonin in causing cranial vasoconstriction, as well as serotonin-enhanced platelet function and aggregation. There is evidence that it also inhibits the peripheral actions of bradykinin. Pizotifen may inhibit serotonin reuptake by blood platelets, which affects the tonicity and decreases passive distension of extracranial arteries. The effects of pizotifen leading to appetite stimulation may be due to the drug acting at the metabolic level rather than a direct stimulation of the appetite centre.

Adults : Usually 1.5 mg daily. This may be taken as a single dose at night or in three divided doses. Dosage should be adjusted to the individual patient requirements up to a maximum of 4.5 mg daily. Up to 3 mg may be given as a single dose. Children (aged over 2 years) : Up to 1.5 mg daily, usually as a divided dose, although up to 1 mg has been given as a single dose at night.

The most common side effects are appetite stimulating effect, increase in body weight and drowsiness.