Flupenthixol, commonly known as Depixol and Fluanxol, is a typical, first-generation antipsychotic medication of the thioxanthene class, that is primarily used to treat schizophrenia. Always consult with your doctor if you are taking any other medications, have allergies, or have been diagnosed with other medical conditions, as misuse of Flupenthixol can have dangerous consequences.

Flupenthixol brand names

Flupenthixol is commonly sold under the following brand names:

  • Fluanxol
  • Depixol
  • Jexit

What is flupenthixol prescribed for?

Flupenthixol is primarily prescribed for the treatment of schizophrenia, in cases where the main symptoms do not include agitation, excitement, or hyperactivity. Since schizophrenic patients often have difficulty with treatment compliance, it is often given in the form of a long-acting injection. [4]

It is generally recommended as maintenance therapy, which is long-term treatment after symptoms are more stable, that decreases the risk of relapse. [1]

In lower doses, it is also used to treat depression, with or without anxiety. [1]

How does flupenthixol work?

The mechanism of action is not fully understood, but it is believed that flupenthixol works by blocking dopamine receptors to help correct chemical imbalances. In turn, this can help reduce symptoms of schizophrenia like hallucinations and delusions. [3]

In lower doses, flupenthixol also has mood-elevating properties, similar to those in tricyclic antidepressants, which can help with depressive symptoms. [1]

How is flupenthixol usually taken?

Flupenthixol is taken either orally as a tablet or through an intramuscular injection. It may take several weeks to see the full effects of this medication. Do not stop taking it without speaking to your doctor.

In tablet form, the starting dose is usually 0.5mg taken three times daily. Your doctor may gradually increase your dosage up to 3-5mg. After you’ve reached a stable dose, your doctor may recommend switching to injections, which are long-acting and easier to remember. [1]

A doctor or nurse must administer the slow-acting injection form of the drug. They will inject the drug into the muscles of your buttocks or upper leg during a scheduled appointment once every two or three weeks. [2] Available doses are 2% or 10%.

Severe side effects may be difficult to predict, so patients should be under close medical supervision until they have reached a stable dose.

How long does flupenthixol stay in your system?

Effects generally begin between 24 and 72 hours after injection, and symptoms continue to improve for two to four weeks after. [1] When taken in tablet form, it may take up to two weeks before you start noticing the effects, and up to six months before negative symptoms fully subside [3]

The half-life of flupenthixol is 35 hours in tablet form or three to eight days for the injection. [4] Half-life is the time it takes for the medication in your system to decrease by half.

After an injection, flupenthixol is still detectable in the blood for up to three weeks. [2]

Flupenthixol side effects

Flupenthixol can cause adverse reactions in some people. Listed below are some of the most common side effects. This list is not conclusive, so let your doctor know if you experience any other unexpected adverse effects.

Mild Side Effects

These side effects are somewhat common [3] and can affect roughly one in ten people taking the drug:

  • Fatigue
  • Dry mouth
  • Dizziness
  • Changes in weight
  • Constipation
  • Increased sweating
  • Increased skin sensitivity to sunlight
  • Insomnia
  • Producing more saliva than usual
  • Pain at the injection site
  • Muscle spasms and aches
  • Muscle stiffness

Severe Side Effects

The following side effects [3] may affect up to one in ten people:

  • Blurred vision or other eye problems
  • Decreased blood pressure, including fainting or dizziness
  • Fast or throbbing heartbeat
  • Shortness of breath

These side effects are uncommon [3], but they may affect one in 100 people:

  • Skin rash
  • Signs of a serious allergic reaction
  • An erection lasting 4 or more hours
  • Confusion

Rarely [3], the following side effects can occur:

  • Seizures
  • Unusual muscle movements (such as tremors, stiffness, or restlessness)
  • Signs of liver damage (such as yellowing of the skin or eyes, dark urine, abdominal pain, and loss of appetite)

Signs of neuroleptic malignant syndrome

Neuroleptic Malignant Syndrome is a rare but potentially fatal condition.

Symptoms include:

  • High fever
  • Irregular or racing heartbeat
  • Confusion
  • Fainting or loss of consciousness
  • Muscle rigidity
  • Sweating [2]

If you experience any of these symptoms, you should stop taking the drug immediately and seek medical attention.

Tardive dyskinesia

Tardive dyskinesia is a rare condition that can develop with continued use. It can cause involuntary, repetitive movements, especially in the face, neck, legs, and arms.

Contact your doctor if you notice any of these symptoms:

  • Lip smacking and uncontrollable tongue movements
  • Grimacing
  • Difficulty swallowing
  • Neck twisting
  • Jerky leg and arm movements [1]

Elevated prolactin levels

Although rare, flupenthixol can increase prolactin levels. Too much of this hormone can decrease the production of estrogen and testosterone, leading to the following symptoms:

  • Changes in the menstrual cycle
  • Sexual dysfunction
  • Enlarged breasts in men
  • Unusual breast milk (in men and women)
  • Fertility problems [2]

If you experience mild side effects that are bothersome, contact your doctor to discuss your options. If you notice any severe side effects, seek immediate medical care from your doctor or the nearest emergency room.

Flupenthixol precautions

Before taking flupenthixol, let your doctor know of any other medications you are taking, as well as any known allergies. Tell your doctor if you are pregnant or breastfeeding, as there have been reports of side effects and withdrawal symptoms in infants exposed to the drug. [2]

Inform your doctor if you regularly consume alcohol or if you take opiates or barbiturates, or if you have had any brain damage or circulatory failure. Taking flupenthixol in these cases can be dangerous, as it increases the sedative effects. [2]

Flupenthixol is not recommended for patients with dementia, as an increased risk of stroke has been reported in this population. [2] There may also be an increased risk of death in patients with dementia-related psychosis. [2]

Let your doctor know if you suffer from any cardiovascular disorders, as flupenthixol can increase the risk of arrhythmias. [1]

It is generally not recommended to take this drug if you have Parkinson’s disease. Flupenthixol can make symptoms worse. [2]

Tell your doctor if you have diabetes, as flupenthixol may affect insulin and glucose responses. [1] On rare occasions, diabetes has developed in patients with no known history of hyperglycemia, so doctors should monitor patients’ blood glucose levels and weight when taking this drug. [2]

It’s important to discuss any history of seizures with your doctor, as flupenthixol can decrease your threshold for seizures. [2]

Flupenthixol can have anticholinergic effects, which can cause fluid pressure in the eye and impact vision. [1] Therefore, you should let your doctor know if you have glaucoma or other eye problems.

Liver damage can cause this drug to build up in the body, which increases the risk of side effects. Flupenthixol can also make liver disease worse. [3]

Additionally, tell your doctor if you have any of the following medical conditions:

  • Cerebrovascular insufficiency
  • Renal insufficiency
  • Hypersensitivity to thioxanthenes or phenothiazine derivatives
  • Kidney disease
  • Family history of blood clots
  • Risk factors for stroke
  • Prostate problems

Do not drive or operate heavy machinery until you know how this medication affects you, as it can cause drowsiness.

Use sunscreen and limit your time in the sun, as this medication can also increase sun sensitivity. [2]

Flupenthixol interactions

The following medications are known to have potentially dangerous interactions with flupenthixol. Please note that this list is not exhaustive and only lists the most severe interactions. Always inform your doctor of all other medications you are taking.

When taken with other antipsychotic drugs or metoclopramide, flupenthixol can increase the risk of side effects, especially the risk of Tardive Dyskinesia. [1]

Flupenthixol may block the effects of levodopa and other drugs used to treat Parkinson’s disease. [1]

This medication can increase the risk of heart problems when taken with antiarrhythmics, like quinidine, or certain antibiotics, including erythromycin. [2] Flupenthixol should not be taken with lithium, as this combination can increase the risk of arrhythmias and other heart problems. [2]

Flupenthixol can decrease the effectiveness of medications for high blood pressure, like guanethidine. [1]

Flupenthixol can increase sedative effects when taken with other drugs that cause drowsiness, such as opioids, barbiturates, muscle relaxants, tricyclic antidepressants, and antihistamines. [2]

Flupenthixol storage

To maintain its efficacy, make sure to store flupenthixol properly. Tablets should be stored in a tightly closed container at room temperature. Do not store them in the bathroom. [2] If you’re taking the injection form, your doctor will store the medication at room temperature, away from direct light and heat.

What to do if you overdose on flupenthixol

Although rare, the effects of an overdose can include:

  • Agitation, confusion, excitement, and convulsions, followed by sedation
  • Unconsciousness
  • Extremely low or high body temperature
  • Low blood pressure
  • Weak pulse
  • Fast heart rate [2]

If you experience these symptoms, you should seek immediate help from your doctor or the nearest hospital. If you don’t get help, potential dangers include ventricular arrhythmias, coma, and cardiac arrest. [1] 

Resources:

  1. Lundbeck Australia Pty Ltd. (2020). Australian product information – FLUANXOL® Depot and FLUANXOL® Concentrated Depot. Retrieved November 1, 2022, from https://www.ebs.tga.gov.au/ebs/picmi/picmirepository.nsf/pdf?OpenAgent&id=CP-2010-PI-05706-3&d=20221019172310101
  2. Lundbeck Canada Inc. (2017). Product Monograph: FLUANXOL® (Flupentixol), as oral tablets or intramuscular injection. Retrieved October 31, 2022, from https://www.lundbeck.com/content/dam/lundbeck-com/americas/canada/products/files/fluanxol_product_monograph_english.pdf
  3. Lundbeck Limited. (2021). Package Leaflet: Depixol® 3mg film-coated tablets. Retrieved November 1, 2022, from https://www.medicines.org.uk/emc/files/pil.997.pdf
  4. Mahapatra, J., Quraishi, S. N., David, A., Sampson, S., & Adams, C. E. (2014). Flupenthixol decanoate (depot) for schizophrenia or other similar psychotic disorders. The Cochrane database of systematic reviews, 2014(6), CD001470. https://doi.org/10.1002/14651858.CD001470.pub2