Generic Name

Phenobarbital Sodium

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Classification

FDA Approved Indications

• Treatment of seizures, including partial and generalized seizures

Mechanism of Action

Enhances the activity of GABA at GABA_A receptors, increasing chloride ion influx and hyperpolarization of neurons, thereby reducing neuronal excitability.

Dosage and Administration

Adult: Initial dose varies based on condition; typically 30-120 mg/day in divided doses, titrated to response.

Pediatric: Dosing individualized based on weight and age; typically 1-5 mg/kg/day, divided doses.

Geriatric: Start at lower doses due to increased sensitivity; titrate carefully.

Renal Impairment: Adjust dosage accordingly; monitoring required.

Hepatic Impairment: Use with caution; monitor liver function; dosage adjustments may be necessary.

Pharmacokinetics

Absorption: Well absorbed after oral administration.

Distribution: Widely distributed in body tissues; crosses blood-brain barrier.

Metabolism: Primarily hepatic via hydroxylation and conjugation.

Excretion: Renal excretion of unchanged drug and metabolites.

Half Life: Approximately 53-118 hours, variable depending on individual factors.

Contraindications

• History of hypersensitivity to barbiturates
• Porphyria

Precautions

• Respiratory depression, hepatocellular disease, history of addiction, risk of dependence, withdrawal hazards

Adverse Reactions - Common

• Sedation, drowsiness (Common)
• Dizziness (Common)
• Cognitive impairment (Common)

Adverse Reactions - Serious

• Respiratory depression (Rare)
• Agranulocytosis, aplastic anemia (Rare)
• Severe allergic reactions (anaphylaxis, angioedema) (Rare)

Drug-Drug Interactions

• Other CNS depressants, leading to enhanced sedation or respiratory depression; Phenytoin, carbamazepine (altered metabolism); Warfarin (altered anticoagulant effect)

Drug-Food Interactions

• Alcohol may enhance CNS depressant effects.

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Do not discontinue abruptly to avoid withdrawal seizures.
• Avoid alcohol and CNS depressants.
• Report signs of hypersensitivity, unusual bleeding, or severe side effects.

Special Considerations

Black Box Warnings:

• Dependence and withdrawal symptoms if discontinued abruptly.
• Potential for respiratory depression.

Genetic Factors: None specifically noted for phenobarbital.

Lab Test Interference: May affect liver function tests and drug levels.

Overdose Management

Signs/Symptoms: Respiratory depression, extreme sedation, coma, hypotension, ataxia.

Treatment: Supportive care, airway management, activated charcoal if recent ingestion, possibly hemodialysis for severe cases.

Storage and Handling

Storage: Store at room temperature, 20-25°C (68-77°F), away from moisture and light.

Stability: Stable when stored properly.