Nembutal Sodium, Novopentobarb 
Classifications: anxiolytic; sedative-hypnotic; barbiturate; anticonvulsant;
Therapeutic: antianxiety
; sedative-hypnotic; anticonvulsant
Prototype: Secobarbital
Pregnancy Category: D
Controlled Substance: Schedule II


50 mg/mL injection


Short-acting barbiturate with anticonvulsant properties. Potent respiratory depressant. Initially, barbiturates suppress REM sleep, but with chronic therapy REM sleep returns to normal.

Therapeutic Effect

Effective as a sedative and hypnotic and anticonvulsant. CNS depression may range from mild sedation to coma, depending on dosage, degree of nervous system excitability, and drug tolerance.


Sedative or hypnotic for preanesthetic medication, induction of general anesthesia, adjunct in manipulative or diagnostic procedures, and emergency control of acute convulsions.


History of sensitivity to barbiturates; parturition, fetal immaturity, uncontrolled pain; ethanol intoxication; hepatic encephalopathy; porphyria; pregnancy (category D), lactation.

Cautious Use

COPD, sleep apnea; heart failure; mental status changes, suicidality, major depression; neonates; renal impairment, renal failure.

Route & Dosage

Preoperative Sedation
Adult: IM 150–200 mg in 2 divided doses
Child: IV 1–3 mg/kg (max: 100 mg)

Adult: IM 150–200 mg IV 100 mg q1–3min up to 500 mg dose
Child: IM 2–6 mg/kg (max: 100 mg)

Status Epilepticus
Adult: IV 2–15 mg/kg loading, then 0.5–3 mg/kg/h
Child: IM 5–15 mg/kg loading, then 0.5–5 mg/kg/h


Note: Do not give within 14 d of starting/stopping an MAO inhibitor.

  • Do not use parenteral solutions that appear cloudy or in which a precipitate has formed.
  • Make IM injections deep into large muscle mass, preferably upper outer quadrant of buttock. Aspirate needle carefully before injecting it to prevent inadvertent entry into blood vessel. Inject no more than 5 mL (250 mg) in any one site because of possible tissue irritation.

PREPARE: Direct: Give undiluted or diluted (preferred) with sterile water, D5W, NS, or other compatible IV solutions.  

ADMINISTER: Direct: Give slowly. Do not exceed rate of 50 mg/min.  

INCOMPATIBILITIES Solution/additive: Atropine, butorphanol, chlorpheniramine, chlorpromazine, cimetidine, codeine, dimenhydrinate, diphenhydramine, droperidol, ephedrine, fentanyl, glycopyrrolate, hydrocortisone, hydroxyzine, inulin, levorphanol, meperidine, methadone, midazolam, morphine, nalbuphine, norepinephrine, tetracyclines, penicillin G, pentazocine, perphenazine, phenytoin, promazine, prochlorperazine, promethazine, ranitidine, sodium bicarbonate, streptomycin, succinylcholine, triflupromazine, vancomycin. Y-site: Amphotericin B cholesteryl, fenoldopam, TPN.

  • Take extreme care to avoid extravasation. Necrosis may result because parenteral solution is highly alkaline.
  • Do not use cloudy or precipitated solution.

Adverse Effects (≥1%)

Body as a Whole: Drowsiness, lethargy, hangover, paradoxical excitement in the older adult patient. CV: Hypotension with rapid IV. Respiratory: With rapid IV (respiratory depression, laryngospasm, bronchospasm, apnea).


Drug: Phenmetrazine antagonizes effects of pentobarbital; cns depressants, alcohol, sedatives add to CNS depression; mao inhibitors cause excessive CNS depression; methoxyflurane creates risk of nephrotoxicity. Herbal: Kava, valerian may potentiate sedation.


Onset: 10–15 min IM; 1 min IV. Duration: 15 min IV. Distribution: Crosses placenta. Metabolism: Primarily in liver. Elimination: In urine. Half-Life: 4–50 h.

Nursing Implications

Assessment & Drug Effects

  • Monitor BP, pulse, and respiration q3–5min during IV administration. Observe patient closely; maintain airway. Have equipment for artificial respiration immediately available.
  • Observe patient closely for adverse effects for at least 30 min after IM administration of hypnotic dose.
  • Monitor for hypersensitivity reactions (see Appendix F) especially with a history of asthma or angioedema.
  • Monitor for adverse CNS effects including exacerbation of depression and suicide ideation.
  • Monitor those in acute pain, children, the elderly, and debilitated patients for paradoxical excitement restlessness.
  • Lab tests: Periodic pentobarbital levels. Note: Plasma levels greater than 30 mcg/mL may be toxic and 65 mcg/mL and above may be lethal.
  • Concurrent drug: Monitor warfarin and phenytoin levels frequently to ensure therapeutic range.

Patient & Family Education

  • Exercise caution when driving or operating machinery for the remainder of day after taking drug.
  • Avoid alcohol and other CNS depressants for 24 h after receiving this drug.
  • Women using oral contraceptives should use an additional, alternative form of contraception.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

© 2006-2023 Last Updated On: 01/26/2023 (0)
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