Dosing and uses of Nembutal (pentobarbital)
Adult dosage forms and strengths
injectable solution: Schedule II
- 50mg/mL
Hypnotic
Initial: 100 mg IV OR 150-200 mg Im
May give small increments of drug after at least 1 minute to reach full effect
Not to exceed 500 mg
Barbiturate Coma
Load: 10-15 mg/kg IV over 30 min; follow by 5 mg/kg IV q1hr for 3 doses
Maintenance: 1 mg/kg/hr IV; may increase to 2-4 mg/kg/hr
Renal Failure
Use lower dose
Hepatic Failure
Use lower dose
Other Indications & Uses
Acute convulsive episodes
Pediatric dosage forms and strengths
injectable solution: Schedule II
- 50mg/mL
Hypnotic
2-6 mg/kg IM once; not to exceed 100 mg
Pre-procedure Sedation
2-6 mg/kg IM, Or
1-3 mg/kg IV
Not to exceed 100 mg Im
Geriatric dosage forms and strengths
Not recommended; use lower dose if use becomes necessary
Nembutal (pentobarbital) adverse (side) effects
Frequency not defined
Angioedema (rare)
Bradycardia
Hypotension
Agitation
Ataxia
CNS depression
Confusion
Dizziness
Fever
Headache
Hyperkinesia
Nightmares
Nervousness
Somnolence (frequent)
Syncope
Rash
Stevens-Johnson syndrome
Constipation
Nausea
Vomiting
Agranulocytosis (rare)
Megaloblastic anemia with prolonged use (rare)
Injury of liver with prolonged use (rare)
SLe
Apnea
Hypoventilation
Warnings
Contraindications
Barbiturate sensitivity, porphyria liver disease, severe respiratory disease
Pregnancy and lactation
Pregnancy category: d
Lactation: secreted in breast milk; use caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Nembutal (pentobarbital)
Mechanism of action
Depresses sensory cortex & decreases motor activity; produces sedation, drowsiness, and hypnosis
Pharmacokinetics
Half-Life: 15-50 hr
Onset: 10-15 min (IM); 3-5 min (IV)
Duration: 3-4 hr
Protein bound: 45-70%
Vd: 0.8 L/kg (children); 1 L/kg (adults)
Metabolism: hepatic microsomal enzymes, glucuronidation
Excretion: Mostly urine
Enzymes induced: CYP1A2, CYP2C9/10, CYP3A4
Administration
IV Incompatibilities
Additive: chlorpheniramine, ephedrine, hydrocortisone, hydroxyzine, insulin (regular), levorphanol, norepinephrine, penicillin G potassium, pentazocine, phenytoin, promazine, promethazine, Na bicarb, streptomycin, succinylcholine, thiopental, triflupromazine, vancomycin
Syringe: butorphanol, chlorpromazine, cimetidine, dimenhydrinate, diphenhydramine, droperidol, fentanyl, glycopyrrolate, hydroxyzine, meperidine, midazolam, morphine, nalbuphine, pentazocine, prochlorperazine, promazine, promethazine, ranitdine
Y-site: amphotericin B cholSO4, fenoldopam
Not spec: cefazolin, clindamycin, diazepam, tetracycline
IV Compatibilities
Additive: amikacin, aminophylline, CaCl2, chloramphenicol, erythromycin, lidocaine, thiopental, verapamiL
Syringe: aminophylline, atropine (<15 min), ephedrine, hyaluronidase, hydromorphone, neostigmine, scopolamine, Na-bicarb, thiopentaL
Y-site: acyclovir, gatifloxacin, insulin, linezolid, propofoL
IV Preparation
Solution: no further prep needed (available form: 50 mg/mL)
IV/IM Administration
IV: slow push; NMT 50 mg/min
- only when other routes not available
IM: NMT 5 mL per site; deep into large muscle
Vials are for multiple use (contains 20 mL=1 g)
