Chemistry:Pimozide

From HandWiki
Short description: Chemical compound


Pimozide
Pimozide.svg
Pimozide-based-on-xtal-3D-bs-17.png
Clinical data
Trade namesOrap
AHFS/Drugs.comMonograph
MedlinePlusa686018
License data
Pregnancy
category
  • AU: B1
  • US: C (Risk not ruled out)
Routes of
administration
Oral
Drug classTypical antipsychotic
ATC code
Legal status
Legal status
Pharmacokinetic data
Bioavailability40-50%
MetabolismCYP3A4, CYP1A2 and CYP2D6
Elimination half-life55 hours (adults), 66 hours (children)
ExcretionUrine
Identifiers
CAS Number
PubChem CID
IUPHAR/BPS
DrugBank
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
Chemical and physical data
FormulaC28H29F2N3O
Molar mass461.557 g·mol−1
3D model (JSmol)
  (verify)

Pimozide (sold under the brand name Orap) is an antipsychotic drug of the diphenylbutylpiperidine class. It was discovered at Janssen Pharmaceutica in 1963. It has a high potency compared to chlorpromazine (ratio 50-70:1). On a weight basis it is even more potent than haloperidol. It also has special neurologic indications for Tourette syndrome and resistant tics. The side effects include akathisia, tardive dyskinesia, and, more rarely, neuroleptic malignant syndrome and prolongation of the QT interval.

Medical uses

Pimozide is used in its oral preparation in schizophrenia and chronic psychosis (on-label indications in Europe only), Tourette syndrome,[1] and resistant tics (Europe, United States and Canada).

There have been numerous studies showing Pimozide can be used successfully to treat Delusional parasitosis and traditionally was the drug of choice. However, newer medications have become prevalent recently as the preferred medication. In one case a series of 33 patients with delusional parasitosis (median age, 60 years), pimozide was prescribed for 24 patients, 18 of whom took the drug. The dose ranged from 1 to 5 mg daily. No information regarding initial dosing was specified, although the dose was continued for 6 weeks prior to tapering. Of those patients receiving pimozide, 61% (11/18) experienced improvement in or full remission of symptoms. The use of pimozide for the treatment of delusional parasitosis is based primarily on data from case series/reports that demonstrate some efficacy in the majority of patients. Currently, atypical antipsychotics such as olanzapine or risperidone are used as first line treatment. However, patients who experience negative side-effects with the first line medications are typically given pimozide.[2][3]

Pimozide has been used in the treatment of delusional disorder and paranoid personality disorder.[4]

Efficacy

A 2013 systematic review compared pimozide with other antipsychotics for schizophrenia or related psychoses:

Pimozide versus any other antipsychotic[5]
Summary
Enough overall consistency over different outcomes and time scales is present to confirm that pimozide is a drug with effectiveness similar to that of other, more commonly used antipsychotic drugs such as chlorpromazine for people with schizophrenia.[5]

Contraindications

It is contraindicated in individuals with either acquired, congenital or a family history of QT interval prolongation.[6] Its use is advised against in individuals with people with either a personal or a family history of arrhythmias or torsades de pointes.[6] Likewise its use is also advised against in individuals with uncorrected hypokalaemia and hypomagnesaemia or clinical significant cardiac disorders (e.g. a recent myocardial infarction or bradycardia.[6] It is also contraindicated in individuals being cotreated with SSRIs or in those with a known hypersensitivity to pimozide or other diphenylbutyl-piperidine derivatives.[6] Likewise its use is contraindicated in individuals receiving treatment with CYP3A4, CYP1A2, or CYP2D6 inhibitors.[6]

Side effects

Very common (>10% frequency) side effects include:[7][6][8][9]

  • Akinesia
  • Constipation
  • Dizziness
  • Dry mouth
  • Hyperhidrosis
  • Nocturia
  • Somnolence
  • Speech disorder

Overdose

Pimozide overdose presents with severe extrapyramidal symptoms, hypotension, sedation, QT interval prolongation and ventricular arrhythmias including torsades de pointes.[6] Gastric lavage, establishment of a patent airway and, if necessary, mechanically assisted respiration is the recommended treatment for pimozide overdose.[6] Cardiac monitoring should be continued for at least 4 days due to the long half-life of pimozide.[6]

Pharmacology

Pimozide acts as an antagonist of the D2, D3, and D4 receptors and the 5-HT7 receptor. It is also a hERG blocker.

Similarly to other typical antipsychotics pimozide has a high affinity for the Dopamine D2 receptor and this likely results in its sexual (due to prolactin hypersecretion) and extrapyramidal side effects as well as its therapeutic efficacy against the positive symptoms of schizophrenia.[10]

Binding profile[Note 1]
Protein Ki (nM)[11] Notes
5-HT1A 650
5-HT2A 48.4 This receptor is believed to be responsible for the atypicality of other antipsychotics like clozapine, olanzapine and quetiapine. Pimozide's affinity towards this receptor is low compared to its affinity for the D2 receptor and hence this receptor unlikely contributes to its effects to any meaningful extent.
5-HT2C 2,112
5-HT6 71
5-HT7 0.5 Relatively high affinity for this receptor may explain its supposed antidepressant-like effects in animal models of depression.[12]
α1A 197.7 Low affinity towards this receptor may explain why pimozide has a lower liability for producing orthostatic hypotension.[10]
α2A 1,593
α2B 821
α2C 376.5
D1 >10,000
D2 0.33 Likely the receptor responsible for the therapeutic effects against the positive symptoms of schizophrenia of antipsychotics like pimozide as well as the prolactin-elevating and extrapyramidal side effect-generating effects of typical antipsychotics like pimozide.[13]
D3 0.25
D4 1.8
hERG 18 May be responsible for pimozide's high liability for prolonging the QT interval.[13]
H1 692 Likely responsible for why pimozide tends to produce so little sedation.[13]
σ 508
Pharmacokinetic data[7][6][8][9]
Pharmacokinetic parameter Value
Time to peak plasma concentration (Tmax) 6-8 hr
Peak plasma concentration (Cmax) 4-19 ng/mL
Elimination half-life (t1/2) 55 hours (adults), 66 hours (children)
Metabolising enzymes CYP3A4, CYP1A2 and CYP2D6
Excretion pathways Urine

History

In 1985 the pimozide was approved by the FDA for marketing as an orphan drug for the treatment of Tourette's syndrome.[1]

See also

Notes

  1. A lower Ki value indicates a stronger binding

References

  1. 1.0 1.1 "Pimozide: use in Tourette's syndrome". Drug Intelligence & Clinical Pharmacy 19 (6): 421–424. June 1985. doi:10.1177/106002808501900602. PMID 3891283. 
  2. "Pimozide: parasitosis (delusional)". Hospital Pharmacy 49 (2): 134–135. February 2014. doi:10.1310/hpj4902-134. PMID 24623867. 
  3. "Successful treatment of delusions of parasitosis with olanzapine". Archives of Dermatology 142 (3): 352–355. March 2006. doi:10.1001/archderm.142.3.352. PMID 16549712. 
  4. Delusional disorder. Cambridge: Cambridge University Press. 1999. ISBN 0-521-58180-X. 
  5. 5.0 5.1 "Pimozide for schizophrenia or related psychoses". The Cochrane Database of Systematic Reviews 11 (11): CD001949. November 2013. doi:10.1002/14651858.CD001949.pub3. PMID 24194433. http://www.cochrane.org/CD001949/SCHIZ_pimozide-for-schizophrenia-or-related-psychoses. 
  6. 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 "Oral 4 mg tablets. - Summary of Product Characteristics". electronic Medicines Compendium. Janssen-Cilag Ltd. 2 April 2013. http://www.medicines.org.uk/emc/medicine/6753/SPC/Orap+4+mg+tablets./. 
  7. 7.0 7.1 "Oral (pimozide) dosing, indications, interactions, adverse effects, and more". Medscape Reference. WebMD. http://reference.medscape.com/drug/orap-pimozide-342982#showall. 
  8. 8.0 8.1 Pimozide. London, UK: Pharmaceutical Press. 12 February 2013. https://www.medicinescomplete.com/mc/martindale/current/7087-n.htm. Retrieved 4 December 2013. 
  9. 9.0 9.1 "ORAP (pimozide) tablet [Teva Select Brands"]. DailyMed. Teva Select Brands. July 2012. http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=fd9729c3-545f-4d34-9bc7-72b61e028fc4. 
  10. 10.0 10.1 The Maudsley prescribing guidelines in psychiatry. West Sussex: Wiley-Blackwell. 2012. ISBN 978-0-470-97948-8. 
  11. "PDSP Ki Database". Psychoactive Drug Screening Program (PDSP). University of North Carolina at Chapel Hill and the United States National Institute of Mental Health. 12 January 2011. http://pdsp.med.unc.edu/pdsp.php. 
  12. "Anti-depressant like Effect of Pimozide in Acute and Chronic Animal Models of Depression". Indian Journal of Pharmaceutical Education and Research 45 (1): 46–53. January–March 2011. 
  13. 13.0 13.1 13.2 Cite error: Invalid <ref> tag; no text was provided for refs named GG

External links