Generic Name

Perphenazine

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Classification

FDA Approved Indications

• Schizophrenia
• Nausea and vomiting (off-label)

Mechanism of Action

Perphenazine blocks dopamine D2 receptors in the brain, thereby reducing symptoms of psychosis and controlling nausea.

Dosage and Administration

Adult: Initially 4-8 mg three times daily. Dosage can be adjusted based on response and tolerability.

Pediatric: Use not generally recommended; consult a specialist.

Geriatric: Start with lower doses, such as 2-4 mg two to three times daily, due to increased sensitivity.

Renal Impairment: Adjust doses carefully; no specific guidelines well established.

Hepatic Impairment: Use cautiously; no specific dose adjustments established.

Pharmacokinetics

Absorption: Well absorbed from gastrointestinal tract.

Distribution: Widely distributed, crosses blood-brain barrier.

Metabolism: Hepatic via CYP450 enzymes.

Excretion: Primarily via urine, some in feces.

Half Life: 6-12 hours, variable.

Contraindications

• Comprise hypersensitivity to phenothiazines or other components.
• Comorbid Parkinson's disease.
• Bone marrow suppression.

Precautions

• Use cautiously in elderly, due to risk of sedation, orthostatic hypotension, and increased mortality in elderly with dementia-related psychosis.
• Monitor for extrapyramidal symptoms, tardive dyskinesia, neuroleptic malignant syndrome, and other adverse effects.

Adverse Reactions - Common

• Drowsiness (Common)
• Extrapyramidal symptoms (EPS) (Common)
• Dry mouth (Common)
• Blurred vision (Common)

Adverse Reactions - Serious

• Neuroleptic malignant syndrome (NMS) (Rare)
• Tardive dyskinesia (Rare)
• Seizures (Rare)
• Blood dyscrasias (e.g., agranulocytosis) (Rare)

Drug-Drug Interactions

• Centrally acting depressants (additive sedation)
• Anticholinergic medications (increased anticholinergic effects)

Drug-Food Interactions

• Alcohol (enhanced sedation)

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Take medication exactly as prescribed.
• Do not stop medication abruptly.
• Report any signs of EPS, NMS, or unusual movements.
• Avoid alcohol and operating heavy machinery until response is known.

Special Considerations

Black Box Warnings:

• Increased mortality in elderly patients with dementia-related psychosis.
• Tardive dyskinesia may be irreversible.

Genetic Factors: Metabolism variability may influence drug levels; CYP450 enzyme activity may affect response.

Lab Test Interference: May cause false-positive results in certain laboratory tests.

Overdose Management

Signs/Symptoms: Extrapyramidal symptoms, hypotension, sedation, seizures, respiratory depression, coma.

Treatment: Supportive care, monitor vital signs, activated charcoal if early, symptomatic treatment for seizures or other adverse effects.

Storage and Handling

Storage: Store at room temperature, away from light and moisture.

Stability: Stable for usual shelf life, check packaging for expiration date.