Adult: In cases caused by various aetiology: 75-125 mg via slow inj to be given as soon as possible after convulsion starts. In cases following the use of local anaesthetics: May require further doses of 125-250 mg to be given via slow inj over 10 minutes; dose is based on the amount of local anaesthetic given and its anticonvulsant properties. Dosing recommendations may vary among individual products and between countries (refer to specific product guidelines). Elderly: Dose reduction may be required.
Intravenous Reduction of raised intracranial pressure
Adult: In neurosurgical patients, if controlled ventilation is provided: 1.5-3 mg/kg via intermittent bolus inj. Dosing recommendations may vary among individual products and between countries (refer to specific product guidelines). Elderly: Dose reduction may be required.
Intravenous Adjunct to anaesthesia, Induction of anaesthesia
Adult: Dose is individualised and adjusted based on patient's response and factors (e.g. age, sex, weight, pre-existing conditions, premedication, concurrent use with other drugs). 100-150 mg via slow inj over 10-15 seconds; may repeat dose after 1 minute if needed. Alternatively, 50-75 mg at intervals of 20-40 seconds, according to response or 3-6 mg/kg as a single dose (Max total: 500 mg). Once anaesthesia has been established, may give additional doses of 25-50 mg as necessary. If given as a sole anaesthetic agent: The desired level of anaesthesia can be maintained by inj of small, repeated doses as needed or using a continuous IV infusion of 0.2 or 0.4% concentration. Dosing recommendations may vary among individual products and between countries (refer to specific product guidelines). Child: Dose is individualised and adjusted based on patient's response and factors (e.g. age, sex, weight, pre-existing conditions, premedication, concurrent use with other drugs). 2-7 mg/kg via slow inj over at least 10-15 seconds; may repeat dose after 1 minute if needed. Dosing recommendations may vary among individual products and between countries (refer to specific product guidelines). Elderly: Dose reduction may be required.
Special Patient Group
Patients with dehydration, severe anaemia; hyperkalaemia, toxaemia, metabolic disorders (e.g. thyrotoxicosis, myxoedema, diabetes), shock; premedicated with narcotic analgesics; patients taking metoclopramide, droperidol: Dose reduction may be required.
Patients with habituation or addiction to alcohol or drugs of abuse: Dose increase may be required. Additionally, it is recommended to use supplementary analgesic drugs.
Hepatic Impairment
Dose reduction may be required.
Reconstitution
Dilute with appropriate amount of water for inj, NaCl 0.9% inj or dextrose 5% inj to prepare the desired concentration. Instruction for reconstitution may vary among individual products or preparations and between countries (refer to specific product guidelines).
Incompatibility
Incompatible with suxamethonium, tubocurarine, pethidine, morphine, promethazine or other acidic drugs; diluents that are too acidic.
Contraindications
Acute asthma, respiratory obstruction, severe respiratory disease, inability to maintain an adequate airway during procedure; severe shock, constrictive pericarditis, porphyria, myotonic dystrophy, complete absence of suitable veins, inflammatory conditions of mouth, jaw, and neck.
Special Precautions
Patient with other respiratory diseases, asthma, severe anaemia, burns, cachexia, CV disease, hypertension, endocrine insufficiency (e.g. Addison's disease, thyrotoxicosis, myxoedema, diabetes), haemodynamic instability (e.g. hypotension, hypovolaemia, dehydration, severe haemorrhage, shock), hyperkalaemia, toxaemia, myasthenia gravis; history of habituation or addiction to alcohol or drug abuse; increased intracranial pressure or blood urea. Debilitated and excessively premedicated patients. Patients taking metoclopramide, droperidol. Renal and hepatic impairment. Children and elderly. Pregnancy and lactation.
Adverse Reactions
Significant: CNS depression, extravasation (e.g. venospasm, irritation, extensive necrosis, sloughing), hypotension, respiratory depression, reduction in cardiac output; risk in precipitating acute circulatory failure (in patients with CV disease, particularly constrictive pericarditis); severe or refractory hypokalaemia (when used for raised intracranial pressure); risk for haemolysis (concentrations <2%). Cardiac disorders: Arrhythmia, myocardial depression. Gastrointestinal disorders: Hiccups. General disorders and administration site conditions: Shivering. Nervous system disorders: Somnolence, delayed wakening. Respiratory, thoracic and mediastinal disorders: Bronchospasm, laryngospasm, coughing, snoring.
This drug may cause prolonged vertigo, disorientation or sedation, if affected, do not drive or operate machinery.
Monitoring Parameters
Monitor heart rate, respiratory rate and blood pressure. A test dose to evaluate patient's tolerance or unusual sensitivity to thiopental sodium is recommended.
Overdosage
Symptoms: Alarming fall in blood pressure, shock, apnoea, laryngospasm, cough and other respiratory difficulties. Management: Secure patent airway; provide ventilation or oxygenation as needed. Monitor and support circulation; administer plasma volume expanders if necessary.
Drug Interactions
Concurrent use with metoclopramide, droperidol, sulfonamides (e.g. sulfisoxazole) may enhance the therapeutic effect of thiopental sodium. May produce synergistic effects on CNS with other CNS depressants (e.g. those used for premedication). May potentiate hypotensive effect, CNS excitatory effects and sedative effects with antipsychotics (e.g. phenothiazine). May potentiate respiratory depressant effect and decrease antinociceptive effect with opioid analgesics. May reduce the analgesic effect of pethidine. May enhance toxicity with ketamine. Diminished therapeutic effect with aminophylline. Potentiated anaesthetic effect with midazolam, probenecid, aspirin. May enhance CNS depressant effect with Mg sulfate. May enhance the hypotensive effect of diazoxide, diuretics, nitrates, antihypertensives (e.g. methyldopa, moxonidine, hydralazine, minoxidil, Ca antagonists, ACE inhibitors, α and β-blockers), adrenergic neurone blockers. May diminish the therapeutic efficacy of estrogen.
Food Interaction
May enhance CNS depressant effect with St. John's wort, alcohol.
Action
Description: Thiopental sodium, a short-acting barbiturate, has hypnotic, sedative and anticonvulsant effect. It exerts different effects on synaptic transmission, particularly those dependent on GABA. Additionally, it reversibly depresses the activity of all excitable tissues.
Synonym: thiopentone. Onset: Anaesthetic: Within 30-40 seconds. Duration: 20-30 minutes after a single dose. Pharmacokinetics: Distribution: Distributed into fatty tissues. Crosses the placenta and enters breast milk. Plasma protein binding: 72-93%. Metabolism: Almost completely metabolised in the liver into inactive metabolites and pentobarbital (small amount). Excretion: Mainly via urine (mostly as inactive metabolites). Elimination half-life: Approx 5-22 hours (low doses); approx 9-50 hours (high doses or long-term infusion).
Chemical Structure
Thiopental sodium Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 23665410, Thiopental sodium. https://pubchem.ncbi.nlm.nih.gov/compound/Thiopental-sodium. Accessed Oct. 26, 2021.
N01AF03 - thiopental ; Belongs to the class of barbiturates. Used as general anesthetics. N05CA19 - thiopental ; Belongs to the class of barbiturates. Used as hypnotics and sedatives.
References
Anon. Thiopental. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 30/07/2021.Buckingham R (ed). Thiopental Sodium. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 30/07/2021.Joint Formulary Committee. Thiopental Sodium. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 30/07/2021.Thiopental 0.5 g and 1 g Powder for Solution for Injection (Mercury Pharmaceuticals Limited). MHRA. https://products.mhra.gov.uk. Accessed 30/07/2021.Thiopental Sodium 500 mg Powder for Solution for Injection (Kyowa Kirin Limited). MHRA. https://products.mhra.gov.uk. Accessed 20/08/2021.Thiopental. Gold Standard Drug Database in ClinicalKey [online]. Elsevier Inc. https://www.clinicalkey.com. Accessed 30/07/2021.Thiosol 500 mg Powder for Injection (Ambica International Trading Corp.). MIMS Philippines. http://www.mims.com/philippines. Accessed 20/08/2021.
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