FLUPHENAZINE
Clinical safety rating: safe
Animal studies have demonstrated safety
Antipsychotic that blocks postsynaptic dopamine D2 receptors in the mesolimbic system, with high potency and additional antagonism at alpha-adrenergic, muscarinic, and histaminergic receptors.
| Metabolism | Primarily hepatic via CYP2D6 and CYP1A2; undergoes conjugation and oxidation to inactive metabolites. |
| Excretion | Primarily hepatic metabolism with biliary excretion. Less than 1% excreted unchanged in urine; fecal elimination accounts for approximately 20-30% of metabolites. |
| Half-life | Terminal elimination half-life is 15-30 hours, but may extend to 40-50 hours after chronic use; clinical context: dosing interval is typically 12-24 hours, and steady-state is reached within 3-5 days. |
| Protein binding | >99% bound to albumin and alpha-1 acid glycoprotein. |
| Volume of Distribution | 10-35 L/kg (mean ~20 L/kg), indicating extensive tissue distribution and accumulation in brain and lung. |
| Bioavailability | Oral: about 40-50% due to first-pass metabolism; IM: 100%. |
| Onset of Action | Oral: 0.5-1 hour; intramuscular (IM): 20-30 minutes; intravenous (IV): 5-10 minutes. |
| Duration of Action | Oral: 6-8 hours; IM: 6-8 hours; IV: 4-6 hours. Note: Duration may be longer with high doses or hepatic impairment; decanoate ester (depot) provides 2-4 weeks of effect. |
| Molecular Weight | 437.52 |
Fluphenazine decanoate (long-acting): 12.5-25 mg IM every 2 weeks; Fluphenazine hydrochloride (oral): 2.5-10 mg daily in divided doses; initial titration 2.5-10 mg/day, maintenance 1-5 mg/day. Maximum oral dose 20 mg/day.
| Dosage form | Injectable |
| Renal impairment | Caution in severe renal impairment (CrCl <10 mL/min). No specific dose adjustment guidelines; use with monitoring. For decanoate, consider reducing dose or extending interval. |
| Liver impairment | Contraindicated in severe hepatic disease (Child-Pugh class C). In mild-to-moderate impairment (Child-Pugh A or B), reduce dose by 25-50% and titrate slowly; monitor for adverse effects. |
| Pediatric use | Oral: Initial 0.25-0.75 mg/day (1-2 divided doses); increase by 0.25-0.5 mg every 1-2 weeks to maximum of 10 mg/day for children 6-12 years. IM decanoate: not recommended in children <12 years. |
| Geriatric use | Initial oral dose: 1-2.5 mg daily; increase slowly by 1-2.5 mg every 4-7 days; typical maintenance 1-5 mg/day. Decanoate: reduced dose 6.25-12.5 mg every 2-4 weeks; monitor for extrapyramidal symptoms. |
| 1st trimester | Limited data; potential risk of congenital malformations based on limited human studies and animal data. Use only if benefit outweighs risk. |
| 2nd trimester | May cause extrapyramidal symptoms in newborn if used near term; consider risk of maternal hypotension and placental hypoperfusion. |
| 3rd trimester | Risk of neonatal extrapyramidal symptoms, jaundice, and prolonged QT interval if used near delivery; avoid or use with caution. |
Clinical note
CNS depressants may enhance sedative effects Can cause extrapyramidal symptoms and neuroleptic malignant syndrome.
| Placental transfer | Fluphenazine crosses the placenta; drug levels in cord blood are similar to maternal serum. Evidence of transfer in human studies. |
| Breastfeeding | Fluphenazine is excreted into breast milk in small amounts; monitor infant for sedation, extrapyramidal symptoms, and impaired weight gain. Use only if clearly needed, preferably lowest effective dose. |
■ FDA Black Box Warning
Increased mortality in elderly patients with dementia-related psychosis.
| Common Effects | Extrapyramidal symptoms |
| Serious Effects |
Comatose statesCNS depression from alcohol or other drugsBlood dyscrasiasKnown hypersensitivity to fluphenazine or phenothiazinesConcurrent use of large doses of other CNS depressants
| Precautions | Tardive dyskinesia may develop, Neuroleptic malignant syndrome (NMS) risk, QT prolongation risk, Hepatic impairment caution, Blood dyscrasias (leukopenia/neutropenia) risk, Antiemetic effect may mask toxicity of other drugs |
| Food/Dietary | Avoid excessive caffeine consumption (energy drinks, coffee, tea) as it may worsen anxiety and agitation. Grapefruit and grapefruit juice may increase serum levels of fluphenazine; limit or avoid concurrent intake. Antacids containing aluminum or magnesium should be separated by at least 2 hours. |
Loading safety data…
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | First trimester: Limited data suggest possible low risk of congenital malformations; avoid if possible. Second and third trimesters: Risk of extrapyramidal symptoms, jaundice, and hyperbilirubinemia in neonates following late exposure. No definite major teratogen. |
| Fetal Monitoring | Monitor maternal blood pressure, weight, and EPS. Fetal: ultrasound for growth and well-being; neonatal assessment for EPS, jaundice, and sedation. |
| Fertility Effects | May elevate prolactin levels causing menstrual irregularities and reduced fertility; effects are reversible upon discontinuation. |
| Clinical Pearls | Fluphenazine is a high-potency first-generation antipsychotic with a strong risk of extrapyramidal symptoms (EPS) such as akathisia, dystonia, and tardive dyskinesia. Use the lowest effective dose; consider prophylactic anticholinergic agents (e.g., benztropine) when initiating therapy in antipsychotic-naïve patients. Monitor for neuroleptic malignant syndrome (NMS) and QT prolongation. Depot formulations require careful adherence monitoring and dose titration. |
| Patient Advice | Avoid alcohol and cannabis; these can worsen side effects or reduce drug effectiveness. · Report any muscle stiffness, fever, altered mental status, or dark urine immediately as these may indicate NMS. · Do not stop taking this medication abruptly; dosage must be tapered under medical supervision. · May cause drowsiness or dizziness; avoid driving or operating heavy machinery until you know how the drug affects you. · Use sun protection as this medication may increase sensitivity to ultraviolet light. · Notify your doctor if you experience involuntary muscle movements, especially of the face or tongue. · Do not take antacids within 2 hours of fluphenazine to avoid absorption interference. |