PENTOBARBITAL
(pen-toe-bar'bi-tal)
Nembutal
PENTOBARBITAL SODIUM
Nembutal Sodium, Novopentobarb 
Classifications: central nervous system agent; anxiolytic; sedative-hypnotic; barbiturate
Prototype: Secobarbital
Pregnancy Category: D
Controlled Substance: Schedule II

Availability

50 mg, 100 mg capsules; 20 mg/5 mL liquid; 30 mg, 60 mg, 120 mg, 200 mg suppositories; 50 mg/mL injection

Actions

Short-acting barbiturate. Potent respiratory depressant. Initially, barbiturates suppress REM sleep, but with chronic therapy REM sleep returns to normal. Has no analgesic properties, and small doses may increase reaction to painful stimuli.

Therapeutic Effects

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

Uses

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

Contraindications

Pregnancy (category D) or lactation. History of sensitivity to barbiturates; parturition, fetal immaturity, uncontrolled pain. Use of sterile injection containing polyethylene glycol vehicle in patients with renal insufficiency.

Cautious Use

Pregnant women with toxemia or history of bleeding.

Route & Dosage

Sedative
Adult: PO 20–30 mg b.i.d. to q.i.d.
Child: PO 2–6 mg/kg/d in 3 divided doses (max: 100 mg/d)

Preoperative Sedation
Adult: PO 150–200 mg in 2 divided doses IM 150–200 mg in 2 divided doses IV 100 mg; may increase to 500 mg if necessary

Hypnotic
Adult: PO 120–200 mg. IM 150–200 mg
Child: PO 30–120 mg. IM 2–6 mg/kg (max: 100 mg)

Administration

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

Intramuscular
Intravenous
  • Use IV route ONLY when other routes are not feasible.

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: Chlorpheniramine, codeine, ephedrine, hydrocortisone, hydroxyzine, inulin, levorphanol, methadone, norepinephrine, tetracyclines, penicillin G, pentazocine, phenytoin, promazine, promethazine, sodium bicarbonate, streptomycin, succinylcholine, triflubromazine, vancomycin, cimetidine, benzquinamide, butorphanol, chlorpromazine, dimenhydrinate, diphenhydramine, droperidol, fentanyl, glycopyrrolate, meperidine, midazolam, morphine, nalbuphine, perphenazine, prochlorperazine, ranitidine. Y-site: Cimetidine, butorphanol, glycopyrrolate, midazolam, nalbuphine, perphenazine, ranitidine.

  • 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).

Interactions

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-kava, valerian may potentiate sedation.

Pharmacokinetics

Onset: 15–30 min PO; 10–15 min IM; 1 min IV. Duration: 1–4 h PO; 15 min IV. Distribution: Crosses placenta. Metabolism: Metabolized primarily in liver. Elimination: Excreted in urine. Half-Life: 4–50 h.

Nursing Implications

Assessment & Drug Effects

Patient & Family Education


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