SODIUM PENTOBARBITAL
Clinical safety rating: avoid
CNS depressants may enhance sedative effects Can cause respiratory depression and dependence.
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.
| 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). |
| Molecular Weight | 248.28 |
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. |
| 1st trimester | Avoid. Associated with fetal malformations (cleft palate) and maternal dependence. Use only if benefit outweighs risk for seizure control. |
| 2nd trimester | Avoid. May cause fetal dependence and withdrawal. Risk of bleeding due to vitamin K deficiency in neonates. |
| 3rd trimester | Avoid. Risk of neonatal respiratory depression, sedation, withdrawal syndrome, and hemorrhagic disease of newborn. |
Clinical note
CNS depressants may enhance sedative effects Can cause respiratory depression and dependence.
| FDA category | Positive |
| Placental transfer | Rapidly crosses placenta. Fetal serum levels approximate maternal levels within minutes. |
| Breastfeeding |
■ 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).
| Common Effects | insomnia |
| Serious Effects |
PorhpyriaSevere respiratory insufficiencyKnown hypersensitivity to barbituratesMarked hepatic impairmentSevere renal impairmentAddiction history (abuse potential)
| 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). |
| Food/Dietary |
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| Excreted into breast milk in low levels. Monitor infant for sedation, poor feeding, and weight gain. Avoid if possible; use alternative if necessary. |
| Lactation Rating | L3 (Moderately Safe) - Limited data, potential adverse effects in infant. |
| Teratogenic Risk | Pregnancy category D. First trimester: Associated with increased risk of congenital malformations, particularly cleft lip/palate and cardiovascular defects, based on animal studies and limited human data. Second and third trimesters: Chronic use may lead to neonatal withdrawal (irritability, hypertonia, seizures) and floppy infant syndrome; near term, respiratory depression in the neonate. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, respiratory rate, and level of sedation. Fetal monitoring: Assess fetal heart rate and movement; consider nonstress test or biophysical profile in chronic use. Neonatal monitoring for withdrawal symptoms if used near term. |
| Fertility Effects | Animal studies have shown decreased fertility and increased preimplantation loss at high doses. Human data are limited, but barbiturates may affect ovarian function and menstrual cyclicity; potential for reduced fertility. |
| Grapefruit and grapefruit juice may increase pentobarbital levels; avoid concurrent use. |
| Clinical Pearls | Sodium pentobarbital is a short-acting barbiturate used for induction of coma in refractory intracranial hypertension and for euthanasia. Monitor for respiratory depression, hypotension, and cardiac arrhythmias. Avoid extravasation due to tissue necrosis. Use with caution in porphyria. Discontinuation may cause withdrawal symptoms; taper slowly. |
| Patient Advice | This medication causes drowsiness and dizziness; avoid driving or operating machinery. · Do not consume alcohol or other CNS depressants. · Abrupt discontinuation may cause withdrawal symptoms like anxiety, tremors, and seizures. · It may be habit-forming; use only as prescribed. · Inform your doctor if you have a history of depression, suicidal thoughts, or substance abuse. |