Acute dystonia

For advice on monitoring for and preventing antipsychotic adverse effects, see Overview of antipsychotic adverse effects.

Dystonia is a sustained or brief muscle contraction resulting in twisting movements or abnormal postures. Dystonia often affects the face, neck and trunk but can be focal, multifocal, segmental (affecting more than one contiguous region) or generalised. Oculogyric crisis, laryngeal spasm and opisthotonus can occur.

Antipsychotic-induced dystonia occurs most often in young males. It generally develops within minutes to days of starting a new antipsychotic or increasing the antipsychotic dose, or starting or stopping an interacting drug.

To treat antipsychotic-induced acute dystonia, options include:

stopping or reducing the dose of other dopamine antagonists (eg metoclopramide)
reducing the antipsychotic dose
switching to an antipsychotic less likely to cause extrapyramidal adverse effects, if the above measures are ineffective or impractical—see Approximate relative frequency of common adverse effects of antipsychotics for approximate relative frequencies of extrapyramidal effects.

While therapy is being adjusted, for symptomatic treatment of antipsychotic-induced acute dystonia, use:

benzatropine 1 to 2 mg (child older than 3 years: 0.02 mg/kg up to 1 mg) intravenously or intramuscularly, as a single dose; if no response, repeat once after 20 minutes. acute dystonia, antipsychotic adverse effect benzatropine benzatropine benzatropine

Following relief of acute signs, switch to oral benzatropine. A typical regimen is:

benzatropine 1 to 2 mg (child older than 3 years: 0.02 mg/kg up to 2 mg) orally, up to twice daily as required for up to 2 weeks; slowly reduce dose over the last few days to stop. benzatropine benzatropine benzatropine