Thiopental Sodium

What it is and how it works

Thiopental is a thiobarbiturate that enhances and, at higher concentrations, directly mimics the action of GABA at GABA-A receptors, producing rapid loss of consciousness within one arm–brain circulation time. Recovery after a single dose is due to redistribution from the brain to other tissues; with repeated doses or infusion it accumulates and recovery is prolonged.

Indications

Induction of general anaesthesia; anaesthesia of short duration; control of refractory convulsive states (status epilepticus) and reduction of raised intracranial pressure in specialist settings.

Dosage and administration (summary)

By slow intravenous injection of a freshly prepared 2.5% solution: for induction, typically 100–150 mg over 10–15 seconds, repeated after 30–60 seconds if required, or according to response (usually up to about 4 mg/kg); reduce dose in elderly, hypovolaemic or debilitated patients.

Contraindications

Acute porphyrias; known hypersensitivity to barbiturates; absence of facilities to maintain the airway and ventilation.

Warnings and precautions

Causes dose-related respiratory and cardiovascular depression; use with caution in hypovolaemia, cardiovascular disease, severe hepatic impairment, myasthenia gravis and asthma. The solution is highly alkaline: extravasation causes tissue necrosis and accidental intra-arterial injection can cause severe pain and gangrene. It has no analgesic effect and may cause laryngospasm.

Pregnancy

Crosses the placenta; may be used for induction (e.g. caesarean section) but large doses can cause neonatal respiratory depression.

Storage and supply

Store the powder below 25 °C, protected from light; reconstituted solution should be used promptly and discarded if it becomes cloudy.

Source: reference summary prepared from the EU SmPC/EPAR, BNF and WHO Model Formulary. The approved product information in Iran governs.