Pimavanserin (Nuplazid) is an atypical antipsychotic explicitly indicated for psychiatric symptoms in Parkinson's disease.

I. Indications

1. Sole Approved Indication:

(1) Treatment of hallucinations and delusions associated with Parkinson's disease psychosis.

(2) This drug is indicated only for patients with a confirmed diagnosis of Parkinson's disease who experience hallucinations and/or delusions that appear after the diagnosis of Parkinson's disease, and whose severity and frequency warrant treatment with an antipsychotic.

2. Important Limitations:

(1) Pimavanserin is not indicated for the treatment of psychiatric symptoms associated with dementia in elderly patients without Parkinson's disease.

(2) There is substantial evidence that antipsychotic drugs increase the risk of all-cause mortality in this patient population, primarily due to cardiovascular events (e.g., heart failure, sudden death) or infections (e.g., pneumonia).

II. Contraindications and Drugs to Avoid

1. Absolute Contraindications:

(1) Hypersensitivity to pimavanserin or any of its components.

(2) Post-marketing reports have included rash, urticaria, angioedema (tongue swelling, perioral edema, throat tightness, dyspnea), and other hypersensitivity reactions.

2. Drugs to Avoid (Cardiac-related):

This drug can prolong the QT interval. Concomitant use with the following should be avoided: Class IA antiarrhythmics (quinidine, procainamide), Class III antiarrhythmics (amiodarone, sotalol), certain antipsychotics (ziprasidone, chlorpromazine, thioridazine), certain antibiotics (gatifloxacin, moxifloxacin).

3. Drugs to Avoid (Metabolic-related):

Avoid concomitant use with strong or moderate CYP3A4 inducers, as they reduce pimavanserin exposure and may decrease efficacy.

4. Drugs Requiring Dose Reduction:

When co-administered with strong CYP3A4 inhibitors (e.g., ketoconazole), the dose of pimavanserin should be reduced to 10 mg per day.

5. Drugs with No Contraindication:

No dose adjustment is required for carbidopa/levodopa when used concomitantly with pimavanserin.

III. Use in Specific Populations

1. Elderly Patients:

No dose adjustment required.

2. Renal Impairment:

(1) No dose adjustment required for patients with mild, moderate, severe renal impairment, or end-stage renal disease.

(2) However, exposure is increased in patients with severe renal impairment (creatinine clearance <30 mL/min); caution is advised.

(3) Dialysis has no significant effect on drug concentrations.

3. Hepatic Impairment:

No dose adjustment required.

4. Pregnancy:

(1) No human data available.

(2) Animal studies did not show teratogenicity, but at high doses (approximately 2 times the recommended human dose), maternal toxicity, reduced pup survival, and decreased body weight were observed.

5. Lactation:

(1) No information is available on the presence of pimavanserin in human milk, its effects on the breastfed infant, or on milk production.

(2) The benefits of breastfeeding should be weighed against the mother's need for the drug.

6. Pediatric Patients:

(1) Safety and effectiveness have not been established.

(2) Efficacy was not demonstrated in clinical trials for irritability associated with autism spectrum disorder in children aged 5-17 years.

7. Other Populations:

No dose adjustment is needed based on age, sex, race, or body weight, as these factors do not affect the pharmacokinetics of pimavanserin.