SODIUM PENTOBARBITAL

Clinical safety rating: avoid

CNS depressants may enhance sedative effects Can cause respiratory depression and dependence.

How it works

Barbiturate that enhances GABA-A receptor activity, prolonging chloride channel opening and increasing inhibitory neurotransmission. At high doses, it acts as a GABA mimetic and depresses neuronal excitability.

What the body does with it

Metabolism	Primarily hepatic via CYP450 enzymes (CYP2C9, CYP2C19), with renal excretion of inactive metabolites.
Excretion	Renal (25-50% unchanged); hepatic metabolism to inactive metabolites; fecal <5%.
Half-life	15-50 hours (dose-dependent; prolonged in hepatic impairment).
Protein binding	45-60% (primarily albumin).
Volume of Distribution	1.0 L/kg (reflects extensive tissue distribution).
Bioavailability	Oral: 70-90%; Rectal: ~90%; IM: 70-100%.
Onset of Action	IV: 30-60 seconds; IM: 10-15 minutes; Oral: 15-60 minutes.
Duration of Action	IV: 15-30 minutes (hypnotic effect); Oral: 3-6 hours (sedative).

Classification & Brands

Dosing & administration

IV: 100-150 mg administered over 1-2 minutes for induction of anesthesia; for seizure control, 100 mg IV every 5-10 minutes up to 500 mg. For maintenance of anesthesia, 50 mg IV as needed every 15-30 minutes. IM: 150-200 mg for preoperative sedation.

Dosage form	CAPSULE
Renal impairment	No specific dose adjustment recommended for GFR >10 mL/min; avoid in severe renal impairment (GFR <10 mL/min) due to prolonged effect and risk of accumulation; use with caution.
Liver impairment	Child-Pugh Class A: No adjustment; Child-Pugh Class B: Reduce dose by 50%; Child-Pugh Class C: Avoid use or reduce dose by 75% with careful monitoring.
Pediatric use	IV induction: 5-6 mg/kg, up to 100 mg; for seizure, 3-5 mg/kg IV every 5-10 minutes up to 10 mg/kg; IM: 2-4 mg/kg for sedation (max 100 mg).
Geriatric use	Reduce dose by 50% due to increased sensitivity and prolonged half-life; use lower initial doses (e.g., 50-75 mg IV) and titrate slowly.

Use during pregnancy

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

Clinical note

CNS depressants may enhance sedative effects Can cause respiratory depression and dependence.

FDA category	Positive
Breastfeeding	Pentobarbital is excreted into breast milk in low concentrations. The milk-to-plasma ratio is approximately 0.3-0.4. Prolonged exposure may cause sedation and poor feeding in the infant. Breastfeeding is generally not recommended during chronic therapy; for single doses, consider discarding milk for 24 hours.
Teratogenic Risk

Warnings & precautions

■ FDA Black Box Warning

WARNING: Risk of respiratory depression, hypotension, and cardiac arrest, especially with rapid intravenous administration. Use only in settings where resuscitation equipment is immediately available. Do not administer intra-arterially (risk of gangrene).

Side Effect Profile

Common Effects	insomnia
Serious Effects

Absolute Contraindications

Hypersensitivity to barbiturates. Porphyria (variegate or acute intermittent). Severe respiratory insufficiency (e.g., COPD with hypercapnia). Hypotension or shock. Status asthmaticus. Known addiction to barbiturates.

Clinical Precautions

Precautions

Respiratory depression (dose-dependent, may require mechanical ventilation). Hypotension and bradycardia (especially with rapid IV administration). Tolerance and dependence potential. Abrupt withdrawal may cause seizures. Caution in hepatic or renal impairment. Avoid extravasation (tissue necrosis).

Clinical Tips & Counseling

Drug interactions

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SODIUM PENTOBARBITAL

Clinical safety rating: avoid

CNS depressants may enhance sedative effects Can cause respiratory depression and dependence.

How it works

What the body does with it

Metabolism	Primarily hepatic via CYP450 enzymes (CYP2C9, CYP2C19), with renal excretion of inactive metabolites.
Excretion	Renal (25-50% unchanged); hepatic metabolism to inactive metabolites; fecal <5%.
Half-life	15-50 hours (dose-dependent; prolonged in hepatic impairment).
Protein binding	45-60% (primarily albumin).
Volume of Distribution	1.0 L/kg (reflects extensive tissue distribution).
Bioavailability	Oral: 70-90%; Rectal: ~90%; IM: 70-100%.
Onset of Action	IV: 30-60 seconds; IM: 10-15 minutes; Oral: 15-60 minutes.
Duration of Action	IV: 15-30 minutes (hypnotic effect); Oral: 3-6 hours (sedative).

Classification & Brands

Dosing & administration

Dosage form	CAPSULE
Renal impairment	No specific dose adjustment recommended for GFR >10 mL/min; avoid in severe renal impairment (GFR <10 mL/min) due to prolonged effect and risk of accumulation; use with caution.
Liver impairment	Child-Pugh Class A: No adjustment; Child-Pugh Class B: Reduce dose by 50%; Child-Pugh Class C: Avoid use or reduce dose by 75% with careful monitoring.
Pediatric use	IV induction: 5-6 mg/kg, up to 100 mg; for seizure, 3-5 mg/kg IV every 5-10 minutes up to 10 mg/kg; IM: 2-4 mg/kg for sedation (max 100 mg).
Geriatric use	Reduce dose by 50% due to increased sensitivity and prolonged half-life; use lower initial doses (e.g., 50-75 mg IV) and titrate slowly.

Use during pregnancy

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

Clinical note

CNS depressants may enhance sedative effects Can cause respiratory depression and dependence.

FDA category	Positive
Breastfeeding	Pentobarbital is excreted into breast milk in low concentrations. The milk-to-plasma ratio is approximately 0.3-0.4. Prolonged exposure may cause sedation and poor feeding in the infant. Breastfeeding is generally not recommended during chronic therapy; for single doses, consider discarding milk for 24 hours.
Teratogenic Risk

Warnings & precautions

■ FDA Black Box Warning

Side Effect Profile

Common Effects	insomnia
Serious Effects