Antipsychotics · Psychiatry
Risperidone
Risperdal®(brand names vary by market)
The atypical that behaves like a typical once the dose climbs.
Also: oral liquid, injection
Mechanism
Potent D2 and 5-HT2A antagonism. The serotonergic component protects against movement disorders only while D2 occupancy stays moderate; above that the protection is lost.
Indications
- Schizophrenia
- Bipolar mania
- Irritability in autism spectrum disorder
- Short-term treatment of severe aggression in dementia, with strict caveats
Formulations
Dosing concepts
The dose window
Extrapyramidal symptoms rise steeply above a threshold dose, so pushing the dose to gain effect often trades one problem for another.
Long-acting injection
A depot formulation exists and is a major adherence tool in relapsing psychotic illness.
Concepts, not prescribing instructions. Practice numbers live in current references and local protocols.
Pharmacokinetics
- Bioavailability
- ~70%
- Half-life
- ~3 h; the active metabolite around 24 h
- Elimination
- hepatic: CYP2D6 to an active metabolite; poor metabolisers and CYP2D6 inhibitors raise exposure
- Protein binding
- ~90%
Adverse effects
- Extrapyramidal symptomscommon & seriousDose-dependent: parkinsonism, akathisia, acute dystonia.
- HyperprolactinemiacommonThe highest of the common atypicals: galactorrhoea, amenorrhoea, sexual dysfunction, and long-term bone effects.
- Weight gaincommon
- Orthostatic hypotensioncommon
- Increased mortality in older adults with dementiaserious
Contraindications & precautions
Contraindications
- Known hypersensitivity
Precautions
- Parkinson disease
- Older adults
- Cardiac disease
- Concurrent CYP2D6 inhibitors such as fluoxetine or paroxetine
Interactions
No curated interaction entries yet for this agent.
Monitoring
Movement examination for extrapyramidal symptoms and akathisia
The dose-limiting effect · At every review
Prolactin if symptomatic
Highest of the common atypicals
Weight, glucose, lipids
Metabolic monitoring applies to the whole class
Counselling points
- Tell us about restlessness or an inability to sit still; that is a treatable side effect, not anxiety.
- Report stiffness, tremor, or unusual movements.
- Stand up slowly at first.
- Do not stop suddenly.
Clinical pearls
- Akathisia is frequently mistaken for worsening agitation, and the instinctive response of increasing the dose makes it worse. Asking whether the restlessness is inside or outside the mind is the distinguishing question.
- Adding fluoxetine or paroxetine to risperidone raises its level through CYP2D6 inhibition and can precipitate extrapyramidal symptoms out of nowhere.
References & review
- Risperidone product monograph (consult the current version for your market) (monograph)
- Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed. (reference-work)
Last reviewed 2026-08-16 · jurisdiction: global · drug information changes; verify against current references before practice use.