NEMBUTAL SODIUM
Clinical safety rating: caution
Comprehensive clinical and safety monograph for NEMBUTAL SODIUM (NEMBUTAL SODIUM).
Barbiturate that enhances GABA-A receptor activity, prolonging chloride channel opening and increasing neuronal inhibition. Depresses the reticular activating system at higher doses.
| Metabolism | Hepatic via CYP2C9 and CYP2C19; undergoes glucuronidation and oxidation to inactive metabolites; enterohepatic recirculation occurs. |
| Excretion | Renal: ~25% unchanged; hepatic metabolism to inactive metabolites; ~50% excreted as metabolites in urine; biliary/fecal: minor. |
| Half-life | Terminal elimination half-life: 15-40 hours in adults; clinically relevant for accumulation with repeated dosing, especially in hepatic impairment. |
| Protein binding | 70-80% bound to albumin and beta globulins. |
| Volume of Distribution | Vd: 0.8-0.9 L/kg; reflects extensive tissue distribution, particularly into fat. |
| Bioavailability | Oral: ~70-90% (variable due to first-pass metabolism); IM: near 100%. |
| Onset of Action | IV: 30-60 seconds (anesthesia); IM: 10-15 minutes (sedation); Oral: 15-30 minutes (sedation). |
| Duration of Action | IV: 5-15 minutes (anesthesia); IM: 1-2 hours (sedation); Oral: 3-6 hours (sedation). Clinical note: Duration depends on redistribution and dose; prolonged in liver disease. |
30 mg IV or IM every 6 to 8 hours as needed for sedation; 65 to 100 mg IV or IM for hypnosis; 200 to 500 mg IV or IM for anticonvulsant effect in status epilepticus. Maximum single dose 500 mg.
| Dosage form | CAPSULE |
| Renal impairment | GFR 10-50 mL/min: Administer every 12-24 hours. GFR <10 mL/min: Administer every 24-48 hours or avoid use due to prolonged half-life. |
| Liver impairment | Child-Pugh Class A: Reduce dose by 25%. Child-Pugh Class B: Reduce dose by 50%. Child-Pugh Class C: Avoid use or reduce dose by 75% with close monitoring. |
| Pediatric use | Neonates: 2-6 mg/kg IV/IM for sedation; Infants and Children: 1-3 mg/kg IV/IM for sedation, up to 5 mg/kg for anticonvulsant; maximum single dose 150 mg. |
| Geriatric use | Initiate with 15-30 mg IV or IM; reduce dose by 50% due to increased sensitivity and decreased clearance; avoid in patients with impaired renal or hepatic function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for NEMBUTAL SODIUM (NEMBUTAL SODIUM).
| Breastfeeding | Pentobarbital is excreted into breast milk with a milk-to-plasma ratio of approximately 0.1–0.3. Although low, exposure may cause sedation, respiratory depression, or feeding difficulties in the neonate, especially with maternal doses > 30 mg/kg. The American Academy of Pediatrics considers pentobarbital compatible with breastfeeding but recommends monitoring for infant drowsiness and weight gain. Alternative agents with lower risk are preferred. |
| Teratogenic Risk | Nembutal Sodium (pentobarbital) is classified as FDA Pregnancy Category D. First trimester: Associated with increased risk of congenital malformations, particularly oral clefts, cardiovascular defects, and neural tube defects. Second and third trimesters: Chronic use can lead to fetal dependence and withdrawal syndrome; acute administration near term may cause neonatal respiratory depression, hypotonia, and hypothermia. Risk of hemorrhagic disease of the newborn due to vitamin K deficiency. |
■ FDA Black Box Warning
May be habit-forming; risk of tolerance, physical and psychological dependence. Abrupt discontinuation may precipitate severe withdrawal reactions including seizures and death. Administer only under strict medical supervision.
| Serious Effects |
Hypersensitivity to barbiturates, porphyria, severe respiratory insufficiency, status asthmaticus, history of addiction to barbiturates.
| Precautions | Respiratory depression, hypotension, and laryngospasm especially with rapid IV administration. Use caution in hepatic/renal impairment, porphyria, or history of substance abuse. Avoid intra-arterial injection (risk of necrosis). |
Loading safety data…
| Fetal Monitoring | Maternal: Monitor vital signs (heart rate, blood pressure, respiratory rate), level of sedation, and signs of respiratory depression. Fetal: Non-stress test and biophysical profile for chronic use; continuous fetal heart rate monitoring during labor if used near delivery. Neonatal: Assess for withdrawal symptoms (irritability, tremors, hypertonia, seizures) and respiratory depression for 24–48 hours after delivery. |
| Fertility Effects | Pentobarbital may interfere with hormonal contraception by inducing hepatic CYP3A4, reducing efficacy of oral contraceptives. In males, high doses can cause testicular atrophy and impaired spermatogenesis in animal studies; human data limited. In females, chronic use may disrupt menstrual cyclicity and ovulation. Reversibility upon discontinuation is presumed. |