Fluphenazine, sold under the brand name Prolixin among others, is a high-potency typical

antipsychotic Antipsychotics, previously known as neuroleptics and major tranquilizers, are a class of Psychiatric medication, psychotropic medication primarily used to manage psychosis (including delusions, hallucinations, paranoia or disordered thought), p ...

medication. It is used in the treatment of chronic

psychoses In psychopathology, psychosis is a condition in which a person is unable to distinguish, in their experience of life, between what is and is not real. Examples of psychotic symptoms are delusions, hallucinations, and disorganized or incoher ...

such as

schizophrenia Schizophrenia () is a mental disorder characterized variously by hallucinations (typically, Auditory hallucination#Schizophrenia, hearing voices), delusions, thought disorder, disorganized thinking and behavior, and Reduced affect display, f ...

, and appears to be about equal in effectiveness to low-potency

s like

chlorpromazine Chlorpromazine (CPZ), marketed under the brand names Thorazine and Largactil among others, is an antipsychotic medication. It is primarily used to treat psychotic disorders such as schizophrenia. Other uses include the treatment of bipolar d ...

. It is given

by mouth Oral administration is a route of administration whereby a substance is taken through the Human mouth, mouth, swallowed, and then processed via the digestive system. This is a common route of administration for many medications. Oral administ ...

injection into a muscle Intramuscular injection, often abbreviated IM, is the injection of a substance into a muscle. In medicine, it is one of several methods for parenteral administration of medications. Intramuscular injection may be preferred because muscles have ...

, or just under the skin. There is also a long acting injectable version that may last for up to four weeks. Fluphenazine decanoate, the

depot injection A depot injection, also known as a long-acting injectable (LAI), is a term for an injection formulation of a medication which releases slowly over time to permit less frequent administration of a medication. They are designed to increase medic ...

form of fluphenazine, should not be used by people with severe depression. Common side effects include movement problems,

sleepiness Somnolence (alternatively sleepiness or drowsiness) is a state of strong desire for sleep, or sleeping for unusually long periods (compare hypersomnia). It has distinct meanings and causes. It can refer to the usual state preceding falling asleep ...

, depression and increased weight. Serious side effects may include

neuroleptic malignant syndrome Neuroleptic malignant syndrome (NMS) is a rare but life-threatening reaction that can occur in response to antipsychotics (neuroleptic) or other drugs that block the effects of dopamine. Symptoms include high fever, confusion, rigid muscles, va ...

, low white blood cell levels, and the potentially permanent movement disorder

tardive dyskinesia Tardive dyskinesia (TD) is an iatrogenic disorder that results in involuntary repetitive body movements, which may include grimacing, sticking out the tongue or smacking the lips, which occurs following treatment with medication. Additional mo ...

. In older people with psychosis as a result of

dementia Dementia is a syndrome associated with many neurodegenerative diseases, characterized by a general decline in cognitive abilities that affects a person's ability to perform activities of daily living, everyday activities. This typically invo ...

it may increase the risk of dying. It may also increase

prolactin Prolactin (PRL), also known as lactotropin and mammotropin, is a protein best known for its role in enabling mammals to produce milk. It is influential in over 300 separate processes in various vertebrates, including humans. Prolactin is secr ...

levels which may result in milk production, enlarged breasts in males,

impotence Erectile dysfunction (ED), also referred to as impotence, is a form of sexual dysfunction in males characterized by the persistent or recurring inability to achieve or maintain a Human penis, penile erection with sufficient rigidity and durat ...

, and the absence of menstrual periods. It is unclear if it is safe for use in

pregnancy Pregnancy is the time during which one or more offspring gestation, gestates inside a woman's uterus. A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Conception (biology), Conception usually occurs ...

. Fluphenazine is a

typical antipsychotic Typical antipsychotics (also known as major tranquilizers, and first generation antipsychotics) are a class of antipsychotic drugs first developed in the 1950s and used to treat psychosis (in particular, schizophrenia). Typical antipsychotics m ...

of the

phenothiazine Phenothiazine, abbreviated PTZ, is an organic compound that has the formula S(C6H4)2NH and is related to the thiazine-class of heterocyclic compounds. Derivatives of phenothiazine are highly bioactive and have widespread use and rich history. ...

class. Its mechanism of action is not entirely clear but believed to be related to its ability to block dopamine receptors. In up to 40% of those on long term phenothiazines, liver function tests become mildly abnormal. Fluphenazine came into use in 1959. The injectable form is on the

World Health Organization's List of Essential Medicines The WHO Model List of Essential Medicines (aka Essential Medicines List or EML), published by the World Health Organization (WHO), contains the medications considered to be most effective and safe to meet the most important needs in a health s ...

. It is available as a

generic medication A generic drug is a pharmaceutical drug that contains the same chemical substance as a drug that was originally protected by chemical patents. Generic drugs are allowed for sale after the patents on the original drugs expire. Because the active ch ...

. It was discontinued in Australia in 2017.

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

. Another 2018 Cochrane review found that there was limited evidence that newer

atypical antipsychotic The atypical antipsychotics (AAP), also known as second generation antipsychotics (SGAs) and serotonin–dopamine antagonists (SDAs), are a group of antipsychotic drugs (antipsychotic drugs in general are also known as tranquilizers and neurol ...

s were more tolerable than fluphenazine. Intramuscular

forms are available as both the

decanoate Capric acid, also known as decanoic acid or decylic acid, is a saturated fatty acid, medium-chain fatty acid (MCFA), and carboxylic acid. Its formula is . Salts and esters of decanoic acid are called caprates or decanoates. The term capric aci ...

and

enanthate Enanthic acid, also called heptanoic acid, is an organic compound composed of a seven-carbon chain terminating in a carboxylic acid functional group. It is a colorless oily liquid with an unpleasant, rancid odor. It contributes to the odor of som ...

esters.

Side effects

Discontinuation

The

British National Formulary The ''British National Formulary'' (BNF) is a United Kingdom (UK) pharmaceutical reference book that contains a wide spectrum of information and advice on prescribing and pharmacology, along with specific facts and details about many medicin ...

recommends a gradual withdrawal when discontinuing antipsychotics to avoid acute withdrawal syndrome or rapid relapse. Symptoms of withdrawal commonly include nausea, vomiting, and loss of appetite. Other symptoms may include restlessness, increased sweating, and trouble sleeping. Less commonly there may be a feeling of the world spinning, numbness, or muscle pains. Symptoms generally resolve after a short period of time. There is tentative evidence that discontinuation of antipsychotics can result in psychosis. It may also result in reoccurrence of the condition that is being treated. Rarely tardive dyskinesia can occur when the medication is stopped.

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.

Pharmacokinetics

History

Fluphenazine came into use in 1959.

Availability

The injectable form is on the

. It is available as a

. It was discontinued in Australia in 2017.

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.

References

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