An antipsychotic for Parkinson's-disease psychosis

Pimavanserin

A medicine used to treat the hallucinations and delusions (psychosis) that can occur in Parkinson's disease.

What is Pimavanserin?

Pimavanserin is a specialist antipsychotic used to treat the hallucinations and delusions (psychosis) that can occur in Parkinson's disease. It works differently from older antipsychotics by acting on a serotonin signal in the brain, which means it is less likely to worsen the movement problems of Parkinson's. It can affect the heart's electrical rhythm (the QT interval), so the heart may be checked. Importantly, like other antipsychotics, it carries a raised risk of death when used in elderly people who have dementia-related psychosis, so it is used carefully under specialist supervision.

Class: Atypical antipsychotic (5-HT2A inverse agonist) · Brands: Nuplazid

Education and reference only. This is a plain-language guide to Pimavanserin — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.

Written by Meds Global Health Clinical Team · Clinically reviewed by Dr Muhammad Suffyan, MB BS, Founder & Clinical Director · Last reviewed · How we review
Class: Atypical antipsychotic (5-HT2A inverse agonist) → Brands: Nuplazid
Pimavanserin (Atypical antipsychotic (5-HT2A inverse agonist)) — Meds Global Health reference card with 2D molecular structure
Pimavanserin — Atypical antipsychotic (5-HT2A inverse agonist). The image shows the active ingredient's 2D molecular structure.

What it is

Pimavanserin is an atypical antipsychotic used to treat the hallucinations and delusions that can develop as part of Parkinson's disease. Older antipsychotics block dopamine, which can make the movement problems of Parkinson's worse, so they are difficult to use in this setting. Pimavanserin instead works mainly on a serotonin signal, which is why it can help the psychosis without worsening movement in the same way. It is taken by mouth and is prescribed and supervised by a specialist, with attention to the heart's rhythm and to the particular risks of using antipsychotics in older people.

How it works

Pimavanserin acts as an inverse agonist at a serotonin receptor in the brain (the 5-HT2A receptor), which is thought to be involved in the hallucinations and delusions seen in Parkinson's-disease psychosis. By dampening this signal rather than blocking dopamine, it can reduce these symptoms while leaving the dopamine pathways that control movement largely untouched. This is why it is less likely than older antipsychotics to stiffen movement or worsen Parkinson's. It works gradually over the early weeks of treatment, and its effect is judged over time.

Company & origin

Originated / developed by: Specialist manufacturer.

A specialist medicine used to treat the hallucinations and delusions that can occur in Parkinson's disease, designed not to worsen movement.

What it treats

Conditions Pimavanserin is used for

Parkinson's diseaseA progressive condition in which the loss of dopamine-producing brain cells causes slownes…

Practical use

How to take Pimavanserin

General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.

  • Take it by mouth as prescribed, at about the same time each day to keep levels steady.
  • Do not expect an instant effect; the benefit on hallucinations and delusions builds over the early weeks.
  • Tell your prescriber about any heart-rhythm problems or other medicines that affect the heart rhythm.
  • Do not stop it suddenly without advice, as your specialist will decide how to adjust or stop it.
  • Report any new confusion, drowsiness or worsening symptoms to your specialist team.

Weighing it up

Advantages & disadvantages of Pimavanserin

Advantages

  • Treats the hallucinations and delusions of Parkinson's-disease psychosis.
  • Less likely than older antipsychotics to worsen the movement problems of Parkinson's.
  • Taken by mouth as a once-daily option.

Disadvantages

  • Like all antipsychotics, carries a raised risk of death in elderly people with dementia-related psychosis.
  • Can lengthen the heart's electrical rhythm (the QT interval) and may need ECG monitoring.
  • Works gradually rather than immediately, so benefit takes time to judge.

Practical use

Good to know

The most important thing to understand is a class warning that applies to all antipsychotics: when they are used in elderly people with dementia-related psychosis, there is a raised risk of death, so the decision to use pimavanserin is weighed very carefully in this group. A key practical safety point is that it can lengthen the heart's electrical rhythm (the QT interval), so an electrocardiogram (ECG) and a review of other QT-affecting medicines may be done before and during treatment. A real advantage in Parkinson's is that, unlike older antipsychotics, it is less likely to worsen the movement symptoms of the condition. It works gradually, so the benefit is judged over the first weeks. As with all of these medicines, it is used under specialist supervision with regular review.

Who should not take it / use with caution

  • People who have had a serious allergic reaction to pimavanserin should not take it.
  • It is used with great caution, if at all, in elderly people with dementia-related psychosis because of the raised risk of death.
  • It is used with caution in people with heart-rhythm problems or those taking other medicines that affect the QT interval.

Monitoring

  • An electrocardiogram (ECG) to check the heart's rhythm before and during treatment where appropriate.
  • Reviewing how well the hallucinations and delusions respond over the early weeks.
  • Watching for confusion, drowsiness or worsening symptoms, particularly in the elderly.

Side effects

  • Swelling of the legs or ankles, nausea or constipation.
  • Confusion or drowsiness in some people, particularly the elderly.
  • Less commonly, changes in the heart's electrical rhythm (the QT interval).

Key interactions

  • Medicines that also affect the heart's QT interval should be reviewed, as the effect can add up.
  • Some medicines change how pimavanserin is broken down, so the dose may need adjusting.
  • Give a full list of your medicines, as several can interact with pimavanserin.

Available as: Capsules or tablets taken by mouth.

Answers

Pimavanserin: frequently asked questions

What is pimavanserin used for?

It is used to treat the hallucinations and delusions (psychosis) that can occur in Parkinson's disease, working on a serotonin signal in the brain.

Will it make my Parkinson's worse?

Unlike older antipsychotics, it is less likely to worsen the movement problems of Parkinson's, because it does not block dopamine in the same way.

Why is there a warning about elderly people with dementia?

Like all antipsychotics, it carries a raised risk of death when used in elderly people with dementia-related psychosis, so it is used very carefully in this group.

Does it affect the heart?

It can lengthen the heart's electrical rhythm (the QT interval), so your team may do an ECG and review other medicines that affect the heart rhythm.

How quickly does it work?

It works gradually, so the benefit on hallucinations and delusions is judged over the first weeks rather than straight away.

The wider class

About Atypical antipsychotic (5-HT2A inverse agonist)

Pimavanserin belongs to the atypical antipsychotic (5-ht2a inverse agonist) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.

AntipsychoticsDrugs for psychosis, bipolar disorder and other conditions — balanced against movement and metabolic side-effects. QuetiapineAn atypical antipsychotic used in schizophrenia and bipolar disorder; can cause sedation, …OlanzapineAn effective atypical antipsychotic for schizophrenia and bipolar disorder, well known for…AripiprazoleAn atypical antipsychotic for schizophrenia and bipolar disorder that tends to be more wei…RisperidoneA widely used atypical antipsychotic for schizophrenia and bipolar disorder, available as …HaloperidolA long-established first-generation antipsychotic used for schizophrenia, agitation and ot…LurasidoneA second-generation antipsychotic used for schizophrenia, often chosen for its relatively …PaliperidoneA second-generation antipsychotic for schizophrenia, available as daily tablets or as a lo…SulpirideAn antipsychotic used to treat schizophrenia; it can raise prolactin and cause movement ef…AmisulprideA second-generation antipsychotic used for schizophrenia that can calm symptoms at higher …ChlorpromazineAn older 'first-generation' antipsychotic used to treat schizophrenia and other conditions…FlupentixolAn antipsychotic for schizophrenia that can be taken as tablets or given as a long-acting …TrifluoperazineA first-generation antipsychotic used in schizophrenia and other psychosis, and at lower a…LevomepromazineA sedating antipsychotic used in psychosis but, in UK practice, most often in palliative c…PericyazineA first-generation (older) antipsychotic used for schizophrenia and severe agitation.…ZuclopenthixolAn older antipsychotic for schizophrenia, available as tablets and as a long-acting depot …AsenapineA second-generation antipsychotic taken as a tablet that dissolves under the tongue, used …CariprazineA second-generation antipsychotic for schizophrenia with a long-lasting effect in the body…DroperidolA butyrophenone medicine used mainly to prevent and treat nausea and vomiting, especially …BenperidolAn antipsychotic occasionally used under specialist care to control deviant antisocial sex…LoxapineAn antipsychotic medicine; its inhaled form is used in hospital settings to calm sudden ag…PericiazineAn older phenothiazine antipsychotic, also used for severe anxiety or agitation, that is m…PimozideAn antipsychotic tablet used for schizophrenia and a specific delusional condition, which …PipotiazineA long-acting antipsychotic given by injection to maintain treatment for schizophrenia.…PromazineAn older antipsychotic used mainly for short-term agitation and restlessness, especially i…FluphenazineAn older antipsychotic used for schizophrenia, often as a long-acting depot injection that…PerphenazineA first-generation antipsychotic used for conditions such as schizophrenia, and also to tr…ZiprasidoneA second-generation antipsychotic used for schizophrenia and bipolar disorder, taken with …BrexpiprazoleA newer antipsychotic used for schizophrenia and as an add-on in depression that has not r…IloperidoneA second-generation antipsychotic used to treat schizophrenia, with the dose built up slow…ThiothixeneA first-generation antipsychotic used to treat schizophrenia, more commonly seen as a Unit…Aripiprazole lauroxilA long-acting depot injection of the antipsychotic aripiprazole, given every few weeks to …LumateperoneA newer once-daily antipsychotic used for schizophrenia and for bipolar depression.…MolindoneAn older first-generation antipsychotic used to treat schizophrenia, mainly available in t…ClozapineThe most effective medicine for schizophrenia that has not responded to other treatments —…

Browse by body system

Mental healthConditions and medicines for mood, anxiety, psychosis, sleep and dependence — used alongsi…

Authoritative sources

  • BNF
  • NICE CKS

Building a medicines information resource?

We create evidence-led, dose-free drug and formulary references for teams.

Talk to us ☎ +44 7448 439750
☎ Call Get a Proposal