risperidoni

Risperidone, sometimes written risperidoni, is an atypical antipsychotic medication used to treat schizophrenia in adults and youths, bipolar disorder, and irritability associated with autism. It is available in oral tablet form, orally disintegrating tablets, and as a long-acting injectable.

The drug works primarily by blocking dopamine D2 receptors and serotonin 5-HT2A receptors in the brain. It also has antagonistic activity at α1-adrenergic and histamine H1 receptors, which can contribute to side effects such as dizziness or sedation. Risperidone is metabolized in the liver to 9-hydroxyrisperidone, an active metabolite that contributes to its therapeutic and adverse effects.

Pharmacokinetically, risperidone is reasonably well absorbed after oral dosing and is processed by liver enzymes including CYP2D6 and CYP3A4. It and its active metabolite are excreted mainly via the kidneys. The injectable form is designed for slower release, allowing less frequent dosing.

Common adverse effects include extrapyramidal symptoms (such as tremor or rigidity), weight gain, sedation, and increased prolactin levels, which can cause menstrual irregularities, galactorrhea, or sexual dysfunction. Other possible effects include orthostatic hypotension, metabolic changes, and headache. In elderly patients with dementia-related psychosis, risperidone is associated with increased mortality risk. It may cause pregnancy-related risks, and is generally categorized as pregnancy category C; caution is advised in nursing and with concurrent medications that affect liver enzymes or heart rhythm.

Therapeutic dosing is individualized. Typical oral doses for adults with schizophrenia or bipolar disorder commonly range from 2 to 6 mg per day, with a maximum often cited around 16 mg daily. Long-acting injectable risperidone is usually given every two weeks in doses such as 25 mg to 50 mg, adjusted by clinician.