Clozapine

Why clozapine is chosen

Clozapine belongs to the antipsychotic group of medicines and treats schizophrenia. It is usually reached for when another antipsychotic has failed to control symptoms, or when side effects made one impossible to carry on with. Hallucinations (hearing or seeing something that isn't there), delusions (beliefs that stay fixed) and jumbled thinking all respond to it, and restlessness and poor sleep often settle too. Tablets come in 25mg, 50mg and 100mg, so the daily amount can be built up in small steps.

How it works and how to take it

Clozapine attaches to dopamine and serotonin receptors — the docking points where chemical messengers pass signals between nerve cells — and damps their activity down. As an atypical antipsychotic, it leaves the limbs much looser than the older drugs do: less stiffness, less tremor, less of the heavy, slow walk.

Swallow each tablet with water. The starting dose is small and climbs over the first week or two, and the day's total is often split in two. Sedation is strong with this medicine, so plenty of people move the whole amount to bedtime. Once a dose suits you, keep to the same times every day.

Side effects

Drowsiness, a dry mouth, blurred vision, light-headedness when standing, a quicker pulse and constipation all turn up in the early weeks. So does extra saliva — a wet pillow in the morning is a common complaint. Appetite grows and weight tends to follow. These usually ease off as the body gets used to the medicine, though the dribbling and the weight often stay.

Effects that need urgent help

Agranulocytosis — a steep fall in the infection-fighting white cells — is rare but serious. Blood counts are checked often at the start and less often later, because a fever, sore throat or mouth ulcers may be the earliest sign and need urgent treatment. Heart muscle inflammation can appear in the first two months; chest pain, breathlessness, palpitations, fever or unexplained tiredness should be acted on at once. Fever with rigid muscles and confusion is another emergency. Seizures grow more likely at higher doses. After months of treatment, uncontrolled movements of the tongue, lips or face can develop.

Interactions, alcohol and storage

Fluvoxamine, ciprofloxacin and a lot of caffeine can make clozapine build up in the blood and strengthen its effects. Cigarette smoke does the opposite, clearing the drug from the body faster. Alcohol, sleeping tablets and benzodiazepines pile on the drowsiness and can bring unsteadiness or a sudden drop in blood pressure. Keep the blister strips below 25°C, out of sunlight and away from damp.