THIOPENTONE SODIUM

It is an ultra short acting thiobarbiturate, highly soluble in water yielding a very alkaline solution, which must be prepared freshly before injection. Extravasation of the soln. or inadvertent intra-arterial injection produces intense pain-necrosis and gangrene may occur. Its undissociated form has high lipid solubility and it enters brain almost instantaneously. Thiopentone is a poor analgesic, painful procedures should not be carried out under its influence. It is a weak muscle relaxant, does not irritate air passages. Thiopentone depresses respiration transiently & BP falls immediately after injection, but recovers rapidly. Cardiovascular collapse may occur if hypovolemia, shock or sepsis are present. It does not sensitize the heart to adrenaline, arrhythmias are rare.

Indications

Anaesthesia of short duration, status epilepticus. Rapid control of convulsions. Infusion of subanaesthetic doses can be used to facilitate verbal communication with psychiatric patients.

Dosage

Inject i.v. (3-5 mg/kg) as a 2.5% soln. it produces unconsciousness in 15-30 sec.

Contra-Indications

Acute intermittent porphyria in susceptible individuals.

Special Precautions

Laryngospasm occurs when respiratory secretions or other irritants are present, or when intubation is attempted. Succinylcholine and thiopentone react chemically & should not be mixed in same syringe. Paediatrics: Dose according to body weight. Pregnancy: Use with caution. Lactation: Use with caution. Elderly: Reduced dose necessary.

Side Effects

Shivering and delirium (during recovery). Nausea & vominting.

Drug Interactions

Phenothiazine antipsychotics increases hypotension, opioid analgesics increases respiratory depression. Promethazine, cyclizine increases excitatory phenomenon. Nitrous oxide, sulphafurazole, aspirin, probenecid increases the dose of thiopentone.