Indications
Fluphenazine Decanoate is a long-acting (depot) antipsychotic injection used for the long-term treatment of schizophrenia and similar psychotic illnesses, especially when it is hard to take tablets every day. It helps prevent relapse once the illness is under control.
How It Works
It blocks dopamine receptors in the brain. Too much dopamine activity is linked to symptoms such as hearing voices, false beliefs and disturbed thinking. The decanoate form is released slowly from the muscle, so one injection works for several weeks.
Dosage and Administration
It is given as a deep injection into a muscle by a doctor or nurse, usually every 2 to 5 weeks. A small test dose is often given first. The dose and interval are set by the psychiatrist, as prescribed. Keep every injection appointment, as missed doses can lead to relapse.
Interactions
- Alcohol, sleeping tablets, sedating antihistamines and opioid painkillers increase drowsiness.
- Other antipsychotics and medicines that affect heart rhythm (for example some antibiotics and antidepressants) raise the risk of heart rhythm problems.
- It can reduce the effect of Levodopa and other Parkinson’s medicines.
- Blood pressure medicines may lower blood pressure too much.
- Medicines such as Trihexyphenidyl, often given for movement side effects, may add to dry mouth, constipation and blurred vision.
Contraindications
- Allergy to fluphenazine or other phenothiazines.
- Severe drowsiness or coma, or severe depression of brain function caused by alcohol or other medicines.
- Serious brain damage, severe heart disease, or blood disorders such as very low white cell count.
- Phaeochromocytoma (a rare adrenal tumour).
- Children.
Side Effects
Common: stiffness, shaking, slow movements, inner restlessness (difficulty sitting still), drowsiness, dry mouth, constipation, blurred vision, weight gain, dizziness on standing, and breast or period changes. Long-term use can cause tardive dyskinesia, uncontrolled movements of the face, tongue or limbs, which may not go away; report any such movements early.
Get urgent medical help if you have high fever with stiff muscles, sweating and confusion (neuroleptic malignant syndrome), a fast or irregular heartbeat or fainting, sudden painful spasm of the neck, jaw, eyes or tongue, sore throat with fever or mouth ulcers, yellow skin or eyes, or difficulty breathing or swallowing.
Pregnancy and Lactation
Use in pregnancy only if the psychiatrist decides the benefit is greater than the risk; if used late in pregnancy the newborn may have stiffness, shaking, sleepiness or feeding problems. It passes into breast milk; breastfeeding is decided by the specialist, and the baby should be watched closely.
Precautions and Warnings
Older people with dementia have a higher risk of stroke and death with antipsychotics, so it is not used for behaviour problems in dementia. Use with care in epilepsy, heart, liver, kidney or lung disease, Parkinson’s disease, glaucoma, enlarged prostate and diabetes. It can affect body temperature control, so avoid overheating and dehydration. Do not drive if drowsy. Do not stop treatment without the psychiatrist’s advice.
Overdose
Because it is given by health staff, overdose is uncommon. Signs include severe drowsiness, marked stiffness or abnormal movements, low blood pressure and heart rhythm problems. Get emergency medical help.
Therapeutic Class
Antipsychotic (typical, phenothiazine group), long-acting depot injection.
Storage
Store below 25°C, protected from light, out of the reach of children. Do not freeze. Usually stored and given at the clinic or hospital.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.