Fluphenazine Decanoate (Prolixin Decanoate)

Introduced 1973

Reviewed by the HeyPsych Medical Review Board

Board-certified psychiatrists and mental health professionals

Indications

Primary Indications

SchizophreniaOther chronic psychotic disorders

Mechanism

Blocks postsynaptic dopamine D2 receptors in the mesolimbic pathway, reducing positive symptoms of psychosis; also antagonizes alpha-adrenergic and histamine receptors.

Dosing

Adult Dosing

start: 12.5–25 mg IM every 2 weeks

titrate: Adjust in increments of 12.5 mg based on response

usual range: 12.5–50 mg every 2–4 weeks

max: 100 mg every 2 weeks

Dosage Forms

Injection (IM oil solution): 25 mg/mL

Onset Duration

Onset within 48–96 hours; duration of action typically 2–4 weeks.

Adverse Effects

Common Side Effects

• extrapyramidal symptoms

• akathisia

• drowsiness

• blurred vision

• dry mouth

• constipation

⚠️ Serious Side Effects

tardive dyskinesia
neuroleptic malignant syndrome
QT prolongation

Warnings

Critical Safety Information

Increased mortality in elderly patients with dementia-related psychosis.

→Risk of EPS is higher with high-potency typical antipsychotics
→Monitor for tardive dyskinesia with long-term use
→Use with caution in cardiovascular disease

Interactions

With: CNS depressants

Risk: Additive sedation

Action: Use caution

With: Levodopa

Risk: Reduced antiparkinsonian effect

Action: Avoid combination

With: QT-prolonging drugs

Risk: Increased risk of arrhythmia

Action: Avoid or monitor ECG

Monitoring

Extrapyramidal symptoms and tardive dyskinesia
Weight, glucose, and lipids
ECG if at risk for QT prolongation

Special Populations

👶Pregnancy

Use only if benefits outweigh risks

🤱Breastfeeding

Excreted in breast milk; use caution

👧Children & Adolescents (Under 18)

Not recommended

👴Older Adults (65+)

Increased sensitivity to EPS and anticholinergic effects

Tapering

Gradual discontinuation recommended; monitor for relapse.

Clinical Notes

Depot formulation is used for maintenance after establishing oral fluphenazine tolerability
Higher potency means more EPS risk compared to low-potency agents

This medication information is for educational purposes only and is not a substitute for professional medical advice. Always consult your healthcare provider before starting, stopping, or changing any medication. Never take medication without a prescription from a licensed healthcare provider.

Interested in this treatment?

This information is for educational purposes. Always consult with a qualified healthcare provider before starting any new treatment.

Locate Psychiatrists