Adult: 150-200 mg as a single dose via deep IM inj. Dosage is individualised according to the patient's age, weight, and condition. Elderly: Dose reduction is recommended. Child: 2-6 mg/kg as a single dose via deep IM inj. Max: 100 mg. Dosage is individualised according to the patient's age, weight, and condition.
Intramuscular Short-term management of insomnia
Adult: 150-200 mg given at bedtime via deep IM inj. Max duration: 2 weeks. Dosage is individualised according to the patient's age, weight, and condition. Elderly: Dose reduction is recommended. Child: 2-6 mg/kg (max: 100 mg/dose) given at bedtime via deep IM inj. Max duration: 2 weeks. Dosage is individualised according to the patient's age, weight, and condition.
Intravenous Emergency management of acute seizures
Adult: For the treatment of cases associated with status epilepticus, cholera, eclampsia, meningitis, tetanus, and toxic reactions to strychnine or local anaesthetics: Initially, 0.5-15 mg/kg via slow IV inj not exceeding 50 mg/min, followed by a continuous infusion of 0.5-5 mg/kg/hour. If with breakthrough status epilepticus, may give an additional bolus dose of 5 mg/kg and titrate the infusion by 0.5-1 mg/kg/hour every 12 hours. Maintaining EEG burst suppression is recommended for 24-48 hours before tapering the infusion. Elderly: Dose reduction is recommended. Child: Initially, 5-15 mg/kg via slow IV inj not exceeding 50 mg/min, followed by a continuous infusion of 0.5-1 mg/kg/hour. If with breakthrough status epilepticus, may give an additional bolus dose of 5 mg/kg and titrate the infusion by 0.5-1 mg/kg/hour every 12 hours until burst suppression. Maintaining EEG burst suppression is recommended for 24-48 hours before tapering the infusion.
Intravenous Preoperative sedation
Adult: Initially, 100 mg via slow IV inj not exceeding 50mg/min (initial dose for 70 kg). May give additional doses (after at least 1 minute) in small increments up to a total of 200-500 mg, as needed. Dosage is individualised according to the patient's age, weight, and condition. Elderly: Dose reduction is recommended. Child: 1-3 mg/kg via slow IV inj every 10 minutes. Max cumulative dose: 6mg/kg (not exceeding 100 mg). Dosage is individualised according to the patient's age, weight, and condition.
Special Patient Group
Debilitated patients: Dose reduction is recommended.
Renal Impairment
Dose reduction is recommended.
Hepatic Impairment
Dose reduction is recommended.
Reconstitution
IV: Available preparation of pentobarbital (50 mg/mL inj solution) may be given undiluted. If necessary, the solution for infusion may be diluted with NaCl 0.9% or dextrose 5% in water to make a concentration of 4 or 8 mg/mL.
Incompatibility
Precipitation may occur with acidic solutions and acidic salts.
Contraindications
History of manifest or latent porphyria.
Special Precautions
Patient with pulmonary disease or respiratory insufficiency (e.g. COPD), sleep apnoea; cardiac disease, heart failure, hypertension or hypotension, shock; depression or suicidal tendencies; low bone density; acute or chronic pain; history of drug abuse. Avoid too rapid IV administration and abrupt withdrawal. Not for use in patients showing premonitory signs of hepatic coma. Hepatic and renal impairment. Children, elderly, or debilitated patients. Pregnancy and lactation.
Adverse Reactions
Significant: CNS depression, respiratory depression; suicidal ideation; paradoxical responses (including agitation, hyperactivity); drug tolerance or psychological and physical dependence and increased risk of osteopenia/osteoporosis (prolonged use); apnoea, laryngospasm, vasodilation with hypotension (rapid IV administration). Blood and lymphatic system disorders: Megaloblastic anaemia. Cardiac disorders: Bradycardia. Gastrointestinal disorders: Nausea, vomiting, constipation. General disorders and administration site conditions: Fever, inj site reaction. Hepatobiliary disorders: Liver damage. Musculoskeletal and connective tissue disorders: Osteopenia or osteoporosis (prolonged use). Nervous system disorders: Headache, anxiety, ataxia, confusion, nervousness. Psychiatric disorders: Insomnia, agitation, abnormality in thinking, hallucination, nightmares, psychiatric disturbance. Skin and subcutaneous tissue disorders: Exfoliative dermatitis, rash. Vascular disorders: Syncope.
This drug may cause dizziness or impair alertness, if affected, do not drive or operate machinery.
Monitoring Parameters
Monitor respiratory status (include pulse oximetry for conscious sedation), CV status, CNS status; blood pressure. Observe the site of administration.
Overdosage
Symptoms: Progression from CNS and respiratory depression to Cheyne-Stokes respiration, areflexia, constriction or dilation of pupils, hypotension, tachycardia, oliguria, lowered body temperature, shock syndrome (e.g. apnoea, circulatory collapse, respiratory arrest), and coma. Ceased brain electrical activity may happen with severe intoxication. Possible occurrence of complications including CHF, cardiac arrhythmias, pneumonia, pulmonary oedema, and renal failure. Management: Symptomatic and supportive treatment. In cases of shock, may start fluid therapy and other standard treatments. May initiate force diuresis to induce the elimination of the drug only for patients with normal kidney function. Consider haemodialysis (not a routine procedure) for anuric or patients in shock and in severe intoxications. Monitor vital signs or fluid balance and maintain adequate airway with assisted respiration or oxygen administration, as needed.
Drug Interactions
Additive CNS depressant effect with other CNS depressants including other sedatives or hypnotics, tranquilizers, or antihistamines. Prolonged effects with MAOIs. Decreased metabolism with valproic acid. May increase metabolism or decrease the serum concentration of anticoagulants (e.g. warfarin, dicumarol), corticosteroids, griseofulvin, doxycycline, phenytoin, and hormonal contraceptives (e.g. estrogen, progesterone).
Food Interaction
May enhance the CNS depressant effect with alcohol.
Action
Description: Mechanism of Action: Pentobarbital is a short-acting barbiturate and a nonselective depressant of the CNS that has hypnotic, sedative, and antiseizure activities. The exact mechanism of action is unknown, but it may be related to its ability to enhance and/or mimic the synaptic action of GABA. Pentobarbital suppresses the ascending conduction in the reticular formation, leading to sensory cortex depression, reduction of motor activity, alteration of cerebral function, and production of its sedative-hypnotic effects; and also enhances the electrical stimulation threshold, contributing to its antiseizure properties. Onset: Sedation: Within 1-5 minutes (IV); 10-15 minutes (IM). Duration: Sedation: 15-45 minutes (IV); 1-2 hours (IM). Pharmacokinetics: Absorption: Time to peak plasma concentration: 30-60 minutes. Distribution: Rapidly distributed into the tissues and fluids including the brain, liver, and kidneys (in high concentrations). Crosses the placenta, enters breastmilk. Plasma protein binding: 45-70%. Metabolism: Metabolised in the liver mainly via oxidation into hydroxypentobarbital (inactive metabolite) and via glucuronidation. Excretion: Via urine (40-50% as hydroxypentobarbital; <60>1% as unchanged drug). Elimination half-life: 22 hours (average). Range: 15-50 hours (dose-dependent).
Chemical Structure
Pentobarbital Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 4737, Pentobarbital. https://pubchem.ncbi.nlm.nih.gov/compound/Pentobarbital. Accessed Nov. 23, 2023.
Storage
Store between 20-25°C. Protect from excessive heat. Do not freeze.
N05CA01 - pentobarbital ; Belongs to the class of barbiturates. Used as hypnotics and sedatives.
References
Anon. Pentobarbital Sodium. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 28/09/2023.Anon. Pentobarbital. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 28/09/2023.Buckingham R (ed). Pentobarbital. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 28/09/2023.Nembutal Sodium Solution Injection (Akorn, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 28/09/2023.Pentobarbital. Gold Standard Drug Database in ClinicalKey [online]. Elsevier Inc. https://www.clinicalkey.com. Accessed 28/09/2023.
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