RISPERNIA

What it is

Risperidone is a novel antipsychotic belonging to a new class of antipsychotic agents, the benzisoxazole-derivatives. Risperidone is a selective monoaminergic antagonist with a high affinity for serotoninergic 5-HT2 and dopaminergic D2 receptors. The antipsychotic activity of risperidone is considered to be attributable to both risperidone and its active metabolite 9-hydroxy risperidone.

Approved indications

— Schizophrenia and related psychoses. — Behavioural disturbances in dementia. — Conduct and other disruptive disorders in children (over 5 years), adolescents and adults with sub average intellectual functioning or mental retardation in whom destructive behaviours (for example, aggression, impulsivity and self-injurious behaviours) are prominent.

Dosing overview

Key safety warnings

Elderly patients with dementia treated with atypical antipsychotic medicines have an increased mortality compared to placebo, with an incidence of mortality of 4.0% for risperidone-treated patients and 3.1% for placebo-treated patients in placebo-controlled trials with risperidone. A higher incidence of mortality was observed in patients treated with frusemide plus risperidone (7.3%) compared to treatment with risperidone alone (3.1%) or frusemide alone (4.1%). In placebo-controlled trials in elderly patients with dementia, there was a significantly higher incidence of cerebrovascular adverse events such as stroke and transient ischaemic attacks with risperidone (3.3%) compared to placebo (1.2%). Neuroleptic Malignant Syndrome (NMS) is a potentially fatal symptom complex that has been reported in association with risperidone, with clinical manifestations including hyperthermia, muscle rigidity, altered mental status and evidence of autonomic instability. Hyperglycaemia, in some cases extreme and associated with ketoacidosis or hyperosmolar coma or death, has been reported in patients treated with atypical antipsychotics including risperidone. Tardive dyskinesia (TD), a syndrome consisting of potentially irreversible, involuntary dyskinetic movements, may develop in patients treated with conventional neuroleptics, and although most prevalent in the elderly, it is impossible to predict at the onset of treatment which patients are likely to develop TD. The most frequent adverse reactions reported with risperidone are insomnia, agitation, extrapyramidal disorder, anxiety, and headache.

Contraindications

Risperidone is contraindicated in patients with a known hypersensitivity to the medicine or any of its excipients.

Regulatory history

Risperidone was first included on the Australian Register of Therapeutic Goods on 26 June 2006.