Fluphenazine Explained

Fluphenazine, sold under the brand name Prolixin among others, is a high-potency typical antipsychotic medication.[1] It is used in the treatment of chronic psychoses such as schizophrenia,[1] [2] and appears to be about equal in effectiveness to low-potency antipsychotics like chlorpromazine.[3] It is given by mouth, injection into a muscle, or just under the skin.[1] There is also a long acting injectable version that may last for up to four weeks.[1] Fluphenazine decanoate, the depot injection form of fluphenazine, should not be used by people with severe depression.[4]

Common side effects include movement problems, sleepiness, depression and increased weight.[1] Serious side effects may include neuroleptic malignant syndrome, low white blood cell levels, and the potentially permanent movement disorder tardive dyskinesia.[1] In older people with psychosis as a result of dementia it may increase the risk of dying.[1] It may also increase prolactin levels which may result in milk production, enlarged breasts in males, impotence, and the absence of menstrual periods.[1] It is unclear if it is safe for use in pregnancy.[1]

Fluphenazine is a typical antipsychotic of the phenothiazine class.[1] Its mechanism of action is not entirely clear but believed to be related to its ability to block dopamine receptors.[1] In up to 40% of those on long term phenothiazines, liver function tests become mildly abnormal.[5]

Fluphenazine came into use in 1959.[6] The injectable form is on the World Health Organization's List of Essential Medicines.[7] It is available as a generic medication.[1] It was discontinued in Australia in 2017.[8]

Medical use

A 2018 Cochrane review found that fluphenazine was an imperfect treatment and other inexpensive drugs less associated with side effects may be an equally effective choice for people with schizophrenia.[9]

Side effects

Discontinuation

The British National Formulary recommends a gradual withdrawal when discontinuing antipsychotics to avoid acute withdrawal syndrome or rapid relapse.[10] Symptoms of withdrawal commonly include nausea, vomiting, and loss of appetite.[11] Other symptoms may include restlessness, increased sweating, and trouble sleeping.[11] Less commonly there may be a feeling of the world spinning, numbness, or muscle pains.[11] Symptoms generally resolve after a short period of time.[11]

There is tentative evidence that discontinuation of antipsychotics can result in psychosis.[12] It may also result in reoccurrence of the condition that is being treated.[13] Rarely tardive dyskinesia can occur when the medication is stopped.[11]

Pharmacology

Pharmacodynamics

Fluphenazine acts primarily by blocking post-synaptic dopaminergic D2 receptors in the basal ganglia, cortical and limbic system. It also blocks α1 adrenergic receptors, muscarinic M1 receptors, and histaminergic H1 receptors.[14] [15]

Fluphenazine[16]
Site Ki (nM) Action Ref
145–2829
334
334
540
3.8–98
174–2,570
4,265– >10,000
145
7.9–38
8
14.45
0.89
1.412
89.12
95–2,590
6.4–9
13
304–314
181.6–320
28.8–122
>10,000
>10,000
7.3–70
560
1,000
>10,000
1,095-3,235.93
2,187.76–7,163
1441–1445.4
5,321
357
Values are Ki (nM). The smaller the value, the more strongly the drug binds to the site. All data are for human cloned proteins, except 5-HT3 (rat), D4 (human/rat), H3 (guinea pig), and NMDA/PCP (rat).

Pharmacokinetics

History

Fluphenazine came into use in 1959.[6]

Availability

The injectable form is on the World Health Organization's List of Essential Medicines. It is available as a generic medication.[1] It was discontinued in Australia in 2017.[8]

Veterinary

In horses, it is sometimes given by injection as an anxiety-relieving medication, though there are many negative common side effects and it is forbidden by many equestrian competition organizations.[17]

Notes and References

  1. Web site: fluphenazine decanoate. The American Society of Health-System Pharmacists. 1 December 2015. live. https://web.archive.org/web/20151208191534/http://www.drugs.com/monograph/fluphenazine-decanoate.html. 8 December 2015.
  2. Web site: Product Information: Modecate (Fluphenazine Decanoate Oily Injection). TGA eBusiness Services. Bristol-Myers Squibb Australia Pty Ltd. 1 November 2012 . 9 December 2013 . PDF. live. https://web.archive.org/web/20170802135209/https://www.ebs.tga.gov.au/ebs/picmi/picmirepository.nsf/pdf?OpenAgent&id=CP-2010-PI-02643-3. 2 August 2017.
  3. Tardy M, Huhn M, Engel RR, Leucht S . Fluphenazine versus low-potency first-generation antipsychotic drugs for schizophrenia . The Cochrane Database of Systematic Reviews . 2014 . 8 . CD009230 . August 2014 . 25087165 . 10.1002/14651858.CD009230.pub2 . 10898219 .
  4. Web site: Modecate Injection 25mg/ml - Patient Information Leaflet (PIL) - (eMC). www.medicines.org.uk. en. 6 November 2017. 7 November 2017. https://web.archive.org/web/20171107012917/http://www.medicines.org.uk/emc/medicine/15355/PIL/Modecate+Injection+25mg+ml. dead.
  5. Fluphenazine. livertox.nih.gov. 2012 . 31643176 . 6 November 2017.
  6. Book: McPherson EM . Pharmaceutical Manufacturing Encyclopedia. . 2007 . Elsevier . Burlington . 9780815518563. 1680 . 3rd .
  7. Book: ((World Health Organization)) . World Health Organization model list of essential medicines: 21st list 2019 . 2019 . 10665/325771 . World Health Organization . World Health Organization . Geneva . WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO . free .
  8. Web site: Fluphenazine - Australian Medicines Handbook. Australian Medicines Handbook. Adelaide, Australia. Australian Medicines Handbook Pty Ltd. Rossi S . July 2017 . 8 August 2017 .
  9. Matar HE, Almerie MQ, Sampson SJ . Fluphenazine (oral) versus placebo for schizophrenia . The Cochrane Database of Systematic Reviews . 6 . CD006352 . June 2018 . 7 . 29893410 . 6513420 . 10.1002/14651858.CD006352.pub3 .
  10. Book: BMJ . Joint Formulary Committee . British National Formulary . 57 . March 2009 . Royal Pharmaceutical Society of Great Britain . United Kingdom . 978-0-85369-845-6 . 192 . 4.2.1 . Withdrawal of antipsychotic drugs after long-term therapy should always be gradual and closely monitored to avoid the risk of acute withdrawal syndromes or rapid relapse..
  11. Book: Haddad P, Haddad PM, Dursun S, Deakin B . Adverse Syndromes and Psychiatric Drugs: A Clinical Guide . 2004 . OUP Oxford . 9780198527480 . 207–216 . en.
  12. Moncrieff J . Does antipsychotic withdrawal provoke psychosis? Review of the literature on rapid onset psychosis (supersensitivity psychosis) and withdrawal-related relapse . Acta Psychiatrica Scandinavica . 114 . 1 . 3–13 . July 2006 . 16774655 . 10.1111/j.1600-0447.2006.00787.x . 6267180 .
  13. Book: Sacchetti E, Vita A, Siracusano A, Fleischhacker W . Adherence to Antipsychotics in Schizophrenia . 2013 . Springer Science & Business Media . 9788847026797 . 85 . en.
  14. Siragusa S, Saadabadi A . Fluphenazine . StatPearls . 2020 . 29083807 .
  15. Web site: Fluphenazine. PubChem . U.S. National Library of Medicine . en. 30 September 2019.
  16. Web site: Bryan Roth . PDSP Ki Database . Psychoactive Drug Screening Program (PDSP) . Roth BL, Driscol J . University of North Carolina at Chapel Hill and the United States National Institute of Mental Health . 14 August 2017 .
  17. Web site: Effects of Behavior-Modifying Drug Investigated (AAEP 2011) . Loving NS . 31 March 2012 . The Horse Media Group . 13 December 2016 . live . https://web.archive.org/web/20170106203758/http://www.thehorse.com/articles/28907/effects-of-behavior-modifying-drug-investigated-aaep-2011 . 6 January 2017 .

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