Products
Risperidone is commercially available as film-coated tablets, meltable tablets, an oral solution, and a suspension for intramuscular administration (Risperdal, generics). The active ingredient has been approved in many countries since 1994.
Structure and properties
Risperidone (C23H27FN4O2, Mr = 410.5 g/mol) exists as a white powder that is practically insoluble in water. It is a benzisoxazole derivative and is biotransformed by CYP2D6 to the active metabolite paliperidone (9-hydroxyrisperidone). Paliperidone is also commercially available (Invega).
Effects
Risperidone (ATC N05AX08) has antipsychotic and potent antidopaminergic properties. The effects are mainly due to antagonism at serotonin 5HT2 receptors and dopamine D2 receptors.
Indications
Risperidone is used to treat schizophrenia and other psychotic disorders. It is additionally approved for the treatment of severe aggression and other psychiatric disorders.
Dosage
According to the SmPC. The drug is administered once or twice daily, regardless of meals.
Contraindications
Risperidone is contraindicated in hypersensitivity and in demented patients with parkinsonian symptoms or Lewy body dementia. For complete precautions, see the drug label.
Interactions
Risperidone is biotransformed predominantly by CYP2D6 to the active metabolite 9-hydroxyrisperidone (paliperidone). Drug-drug interactions are possible with CYP inhibitors and inducers. Other interactions have been described with levodopa, dopamine agonists, SSRIs, antihypertensives, drugs that prolong the QT interval, and furosemide, among others.
Adverse effects
The most common potential adverse effects include drug-induced parkinsonian symptoms, drowsiness, headache, and insomnia. Risperidone may prolong the QT interval. Numerous other side effects have been observed.
