ETRAFON-FORTE

Clinical safety rating: caution

Comprehensive clinical and safety monograph for ETRAFON-FORTE (ETRAFON-FORTE).

How it works

ETRAFON-FORTE is a combination of perphenazine (a phenothiazine antipsychotic) and amitriptyline (a tricyclic antidepressant). Perphenazine blocks postsynaptic dopamine D2 receptors in the mesolimbic system. Amitriptyline inhibits reuptake of serotonin and norepinephrine, enhancing neurotransmission. Additionally, amitriptyline blocks histamine H1, muscarinic, and alpha-adrenergic receptors.

What the body does with it

Metabolism	Perphenazine is metabolized primarily by CYP2D6, with minor contributions from CYP3A4. Amitriptyline is metabolized by CYP2C19, CYP1A2, and CYP2D6 to nortriptyline.
Excretion	Primarily renal (approximately 70-80% as metabolites, <5% unchanged). Biliary/fecal elimination accounts for about 15-20% due to enterohepatic recirculation of metabolites.
Half-life	Terminal elimination half-life of perphenazine: 8-12 hours; amitriptyline: 13-36 hours (mean ~20 hours). Steady-state achieved in 3-7 days. Clinical context: twice-daily dosing maintains therapeutic levels.
Protein binding	Perphenazine: ~90% bound to albumin and alpha-1-acid glycoprotein. Amitriptyline: ~96% bound primarily to albumin and alpha-1-acid glycoprotein.
Volume of Distribution	Perphenazine: 10-15 L/kg; amitriptyline: 15-20 L/kg. Large Vd indicates extensive tissue distribution, particularly in brain, liver, and lungs.
Bioavailability	Oral: Perphenazine 40-60% (first-pass metabolism); amitriptyline 45-60% (first-pass metabolism). IM: Perphenazine ~100%.
Onset of Action	Oral: 1-3 hours for perphenazine (antipsychotic effect); 2-6 hours for amitriptyline (antidepressant effect). Peak plasma concentrations at 2-4 hours (perphenazine) and 2-8 hours (amitriptyline).
Duration of Action	Perphenazine: 6-12 hours; amitriptyline: 24-72 hours for antidepressant effect. Clinical note: Therapeutic response in depression may take 1-4 weeks. Antipsychotic effects may be seen within days.

Classification & Brands

Dosing & administration

ETRAFON-FORTE (perphenazine 4 mg / amitriptyline 25 mg) oral tablets: 1 tablet three times daily or 1 tablet four times daily. Maximum daily dose: 4 tablets (perphenazine 16 mg / amitriptyline 100 mg).

Dosage form	TABLET
Renal impairment	GFR 10-50 mL/min: reduce dose by 50% or increase dosing interval; GFR <10 mL/min: avoid use or reduce dose by 75%.
Liver impairment	Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated.
Pediatric use	Not recommended in children under 12 years. Adolescents: initial dose perphenazine 2 mg / amitriptyline 10 mg orally three times daily, titrate based on response; maximum perphenazine 16 mg / amitriptyline 100 mg daily.
Geriatric use	Initial dose: perphenazine 1 mg / amitriptyline 10 mg orally twice daily; titrate slowly; monitor for anticholinergic effects, orthostatic hypotension, and sedation. Maximum daily dose: perphenazine 8 mg / amitriptyline 50 mg.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for ETRAFON-FORTE (ETRAFON-FORTE).

Breastfeeding	Perphenazine excreted into breast milk in low amounts (M/P ratio ~0.5-1.0); amitriptyline M/P ratio ~0.8-1.5. Combined use may cause drowsiness, irritability in infant. Clinical significance unclear; weigh risk vs. benefit.
Teratogenic Risk	FDA Pregnancy Category D. First trimester: association with congenital malformations (neural tube defects, cardiovascular anomalies). Third trimester: prolonged exposure may cause neonatal withdrawal (irritability, hypertonia) and persistent pulmonary hypertension. Avoid in pregnant women unless benefit outweighs risk.

Warnings & precautions

■ FDA Black Box Warning

WARNING: Increased mortality in elderly patients with dementia-related psychosis. Antidepressants increased the risk of suicidal thinking and behavior in children, adolescents, and young adults in short-term studies. Not approved for use in pediatric patients.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to perphenazine, amitriptyline, or any component","Concomitant use with MAOIs or within 14 days of MAOI therapy","Recent myocardial infarction","Severe hepatic impairment","Angle-closure glaucoma","Urinary retention","Concomitant use with drugs that prolong QTc interval"]

Clinical Precautions

Precautions

["Risk of extrapyramidal symptoms, tardive dyskinesia, and neuroleptic malignant syndrome due to perphenazine","Anticholinergic effects including urinary retention, constipation, and glaucoma exacerbation from amitriptyline","Cardiotoxicity: QTc prolongation, arrhythmias, and myocardial infarction risk","Avoid abrupt discontinuation to prevent withdrawal symptoms","May impair mental or physical abilities; caution with alcohol and CNS depressants","Hepatic impairment, renal impairment, and hypothyroidism require dose adjustment"]

Clinical Tips & Counseling

Drug interactions

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ETRAFON-FORTE

Clinical safety rating: caution

Comprehensive clinical and safety monograph for ETRAFON-FORTE (ETRAFON-FORTE).

How it works

What the body does with it

Metabolism	Perphenazine is metabolized primarily by CYP2D6, with minor contributions from CYP3A4. Amitriptyline is metabolized by CYP2C19, CYP1A2, and CYP2D6 to nortriptyline.
Excretion	Primarily renal (approximately 70-80% as metabolites, <5% unchanged). Biliary/fecal elimination accounts for about 15-20% due to enterohepatic recirculation of metabolites.
Half-life	Terminal elimination half-life of perphenazine: 8-12 hours; amitriptyline: 13-36 hours (mean ~20 hours). Steady-state achieved in 3-7 days. Clinical context: twice-daily dosing maintains therapeutic levels.
Protein binding	Perphenazine: ~90% bound to albumin and alpha-1-acid glycoprotein. Amitriptyline: ~96% bound primarily to albumin and alpha-1-acid glycoprotein.
Volume of Distribution	Perphenazine: 10-15 L/kg; amitriptyline: 15-20 L/kg. Large Vd indicates extensive tissue distribution, particularly in brain, liver, and lungs.
Bioavailability	Oral: Perphenazine 40-60% (first-pass metabolism); amitriptyline 45-60% (first-pass metabolism). IM: Perphenazine ~100%.
Onset of Action	Oral: 1-3 hours for perphenazine (antipsychotic effect); 2-6 hours for amitriptyline (antidepressant effect). Peak plasma concentrations at 2-4 hours (perphenazine) and 2-8 hours (amitriptyline).
Duration of Action	Perphenazine: 6-12 hours; amitriptyline: 24-72 hours for antidepressant effect. Clinical note: Therapeutic response in depression may take 1-4 weeks. Antipsychotic effects may be seen within days.

Classification & Brands

Dosing & administration

Dosage form	TABLET
Renal impairment	GFR 10-50 mL/min: reduce dose by 50% or increase dosing interval; GFR <10 mL/min: avoid use or reduce dose by 75%.
Liver impairment	Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated.
Pediatric use	Not recommended in children under 12 years. Adolescents: initial dose perphenazine 2 mg / amitriptyline 10 mg orally three times daily, titrate based on response; maximum perphenazine 16 mg / amitriptyline 100 mg daily.
Geriatric use	Initial dose: perphenazine 1 mg / amitriptyline 10 mg orally twice daily; titrate slowly; monitor for anticholinergic effects, orthostatic hypotension, and sedation. Maximum daily dose: perphenazine 8 mg / amitriptyline 50 mg.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for ETRAFON-FORTE (ETRAFON-FORTE).

Breastfeeding	Perphenazine excreted into breast milk in low amounts (M/P ratio ~0.5-1.0); amitriptyline M/P ratio ~0.8-1.5. Combined use may cause drowsiness, irritability in infant. Clinical significance unclear; weigh risk vs. benefit.
Teratogenic Risk	FDA Pregnancy Category D. First trimester: association with congenital malformations (neural tube defects, cardiovascular anomalies). Third trimester: prolonged exposure may cause neonatal withdrawal (irritability, hypertonia) and persistent pulmonary hypertension. Avoid in pregnant women unless benefit outweighs risk.