[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Second-generation antipsychotics](https://durgical.com/en/pharmacology/classes/second-generation-antipsychotics/) › Pimavanserin # Pimavanserin ## Second-generation antipsychotics? Second-generation antipsychotics A 5-HT2A inverse agonist with no dopamine blockade, used for hallucinations and delusions of Parkinson disease psychosis without worsening movement. Updated Nov 1, 2026 ## Quick facts **Group** [Second-generation antipsychotics](https://durgical.com/en/pharmacology/classes/second-generation-antipsychotics/) **Target** Serotonin 5-HT2A receptor (inverse agonist) **Used for** Hallucinations **Key effects** Peripheral oedema · Confusion **Monitor** ECG in people with QT risk factors **ATC** N05AX17 No doses: the clinician sets them by the current guideline. On this page - The basics Mechanism of action - Indications - Adverse effects - Pharmacokinetics - Memory aid - Safety Contraindications - Key interactions - What is monitored - Administration and safety - Pregnancy and breastfeeding - Nursing care - Study Test yourself - Connections Connections ## Mechanism of action ◎**Serotonin 5-HT2A receptor (inverse agonist)**Pimavanserin ⓘ The figure shows pimavanserin bound to the human serotonin 5-HT2A receptor (fused to a small protein for crystallisation). **Target in 3D:** Serotonin 5-HT2A receptor (inverse agonist). PDB structure 9WZO (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/9WZO) · Drag to rotate · pinch to zoom Pimavanserin is an inverse agonist and antagonist at serotonin 5-HT2A receptors, and to a lesser degree at 5-HT2C. It has no meaningful dopamine receptor binding. Because it does not block D2, it treats hallucinations and delusions in Parkinson disease psychosis without worsening parkinsonism, the problem with most antipsychotics in these patients. - Pimavanserin switches off 5-HT2A receptors (inverse agonist) - Less cortical 5-HT2A signalling: fewer hallucinations - No D2 block: parkinsonism does not worsen - Watch for QT prolongation ## Indications - Hallucinations and delusions associated with Parkinson disease psychosis [Parkinson disease →](https://durgical.com/en/conditions/parkinson-disease/) ## Adverse effects ### Common - Peripheral oedema (swollen legs) - Confusion ### Serious (rare, important) - Higher mortality in older people with dementia-related psychosis (boxed warning), unless the psychosis is due to Parkinson disease - QT prolongation ## Contraindications - Hypersensitivity to pimavanserin ## Key interactions **Strong CYP3A4 inhibitors (ketoconazole, clarithromycin)** Higher levels; the amount is reduced **Strong or moderate CYP3A4 inducers (rifampicin, carbamazepine, phenytoin)** Avoided: loss of effect **Other QT-prolonging drugs (class Ia and III antiarrhythmics, some antipsychotics and antibiotics)** Additive QT prolongation ## What is monitored - ECG in people with QT risk factors - Swelling of the legs, confusion and falls - Parkinson motor symptoms (should not worsen) ## Administration and safety - Capsules may be opened and mixed with a spoonful of soft food, eaten at once and not stored - Its long half-life means effects fade slowly after stopping ## Pregnancy and breastfeeding Human data are very limited; use weighs benefit and risk. ## Nursing care - Records how often hallucinations and delusions occur, to judge the response - Checks legs for swelling and watches for confusion and falls - Reviews the medicine list for QT-prolonging drugs and CYP3A4 inhibitors or inducers - Reports palpitations or fainting ## Pharmacokinetics **Absorption** Taken by mouth; capsules can be opened onto soft food **Metabolism** Liver, mainly CYP3A4, to an active N-desmethyl metabolite **Half-life** About 57 hours (about 200 hours for the active metabolite) ## Memory aid «PIMAVANSERIN spares the Parkinson»: it hits Serotonin 2A only, so dopamine (and movement) is left alone. ## Test yourself Think of the answer, then tap the question to see it. ## Why does pimavanserin not worsen parkinsonism? It does not block dopamine receptors; it acts as an inverse agonist at 5-HT2A. ## What is pimavanserin approved for? Hallucinations and delusions of Parkinson disease psychosis. ## Which ECG effect is a warning for pimavanserin? QT prolongation. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/pimavanserin/) [More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology) ## Connections ## Related drugs 2 - [Quetiapine](https://durgical.com/en/pharmacology/quetiapine/) - [Clozapine](https://durgical.com/en/pharmacology/clozapine/) ## Related conditions 1 - [Parkinson disease](https://durgical.com/en/conditions/parkinson-disease/) [← Back to the class: Second-generation antipsychotics](https://durgical.com/en/pharmacology/classes/second-generation-antipsychotics/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [DailyMed - PIMAVANSERIN capsule](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=403b6540-c53d-4e92-91b4-36ca6338b2b1) (DailyMed (U.S. National Library of Medicine), 2026); [Pimavanserin: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a616032.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=N05AX17) (WHO Collaborating Centre for Drug Statistics Methodology, 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/pimavanserin/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/pimavanserin/