Phenobarbital

Phenobarbital

Drug monograph · NCLEX study reference
Therapeutic class	Anticonvulsant, sedative
Pharmacologic class	Barbiturate (controlled C-IV)
Onset / peak / duration	Long acting.
Half-life / level	Half-life 53 to 118 hours; therapeutic level 15 to 40 mcg/mL.
Routes	PO (oral), IV
High-alert (ISMP)	No
Black box warning	None
Antidote / reversal	Supportive care; no specific reversal.
Pregnancy / lactation	Use only if essential.

Nursing pharmacology study reference (NCLEX-style monograph). Numeric values are standard teaching ranges for study and must be verified against current manufacturer labeling before clinical use. This is educational content, not prescribing guidance.

Phenobarbital — Anticonvulsant, sedative; Barbiturate (controlled C-IV).

Identification

• Therapeutic class: Anticonvulsant, sedative.
• Pharmacologic class: Barbiturate (controlled C-IV).

Pharmacology

• Mechanism of action: Enhances GABA activity to raise the seizure threshold.
• Onset / peak / duration: Long acting.
• Half-life / therapeutic level: Half-life 53 to 118 hours; therapeutic level 15 to 40 mcg/mL.

Clinical use

• Indications: Seizures (including neonatal and status), sedation.
• Usual dose, route, frequency: PO or IV, dosed by level.
• Maximum dose / adjustments: Slow IV administration; reduce in hepatic and renal impairment.

Safety

• Contraindications: Porphyria, severe respiratory disease, prior dependence.
• Black box warning: None.
• Interactions: Strong CYP inducer (lowers many drugs), CNS depressants and alcohol (respiratory depression), warfarin, oral contraceptives.
• Pregnancy / lactation: Use only if essential.
• High-alert: No.

Adverse effects

• Common side effects: Sedation, dizziness, cognitive slowing.
• Serious effects to report: Respiratory depression, dependence, severe rash.
• Antidote / reversal: Supportive care; no specific reversal.

Nursing process

• Assessment before administration: Respiratory status, level, seizure baseline.
• Interventions during therapy: Slow IV; monitor respirations; taper to stop.
• Monitor: Drug level, respiratory status, seizure frequency.
• Evaluation / expected outcome: Seizure control.

Patient teaching

• Patient teaching: Avoid alcohol; do not stop abruptly; backup contraception.
• Notify provider if: Slowed breathing, rash, excessive drowsiness.
• Administration tips: Slow IV; consistent dosing.