THIOPENTAL SODIUM

Intravenous injection. 5% w/v (500mg in 20ml) solution. On occasions it may be administered as a 5% w/v solution (500mg in 10ml). 5% w/v solution and this should be discarded after seven hours. ) Use in anaesthesia Normal dosage for the induction of anaesthesia is 100mg to 150mg injected over 10 to 15 seconds.

If necessary a repeat dose of 100mg to 150mg may be given after one minute. No fixed dosage recommendations for the intravenous injection can be given, since the dosage will need to be carefully adjusted according to the patient’s response.

Factors such as age, sex, and weight of the patient should be taken into consideration. Thiopental sodium reaches effective concentrations in the brain within 30 seconds and anaesthesia is normally produced within one minute of an intravenous dose.

5% w/v solution. A repeat dose of 100mg to 150mg may be given after one minute. The intravenous injection should be given slowly and the amounts given titrated against the patient’s response to minimise the risk of respiratory depression or the possibility of overdosage.

5% w/v solution) with a maximum of 500mg. 5% w/v solution. A repeat dose of 2 to 7mg/kg may be given after one minute. The dose is 2 to 7mg/kg based on the patient’s response. The dose for children should not exceed 7mg/kg. Elderly Smaller adult doses are advisable.

5% w/v solution) should be given as soon as possible after the convulsion begins. Further doses may be required to control convulsions following the use of a local anaesthetic. Other regimens, such as the use of intravenous or rectal diazepam, may be used to control convulsive states.

5 to 3mg/kg of bodyweight may be given to reduce elevations of intracranial pressure if controlled ventilation is provided.

Summary of the safety profile Laryngeal spasm may occur, together with coughing or sneezing, during the induction procedure. For this reason it is not advised to use thiopental sodium alone for peroral endoscopy. A fall in blood pressure is often seen when thiopental sodium is first given.

Although frequencies established in controlled clinical trials are not available for thiopental sodium, the following are known to be relatively common in patients post general anaesthesia: drowsiness; nausea, with or without vomiting; decreased appetite; malaise; fatigue; dizziness; headache; and delirium in elderly patients.

Excessive doses are associated with hypothermia and profound cerebral impairment. Tabulated summary of adverse reactions Adverse reactions from literature searches, the KKI database and spontaneous reports with thiopental sodium are listed in the table below.

Within the system organ class, the adverse reactions are listed by frequency using the following convention: very common (≥1/10); common (≥1/100 to <1/10); uncommon (≥1/1,000 to <1/100); rare (≥1/10,000 to <1/1,000); very rare (<1/10,000) and not known (cannot be estimated from the available data).

System Organ Class Adverse reaction Frequency Immune system disorder Hypersensitivity, anaphylactic and anaphylactoid reactions Not known Metabolism and nutrition disorders Decreased appetite, hypokalaemia, hyperkalaemia Not known Psychiatric disorders Delirium, confusional state Not known Nervous system disorders Cerebral impairment, amnesia, dizziness, somnolence, headache Not known Cardiac disorders Myocardial depression, arrhythmia Not known Vascular disorders Hypotension, circulatory collapse Not known Respiratory, thoracic and mediastinal disorders Bronchospasm, respiratory depression, laryngospasm, cough, sneezing, apnoea Not known Gastrointestinal disorders Nausea, vomiting Not known Skin and subcutaneous tissue disorders Skin reaction Not known General disorders and administration site conditions Malaise, fatigue, chills, extravasation, hypothermia Not known Investigations Cardiac output decreased, blood pressure decreased Not known Reporting of suspected adverse reactions Reporting suspected adverse reactions after authorisation of the medicinal product is important.

Thiopental sodium causes respiratory depression and a reduction in cardiac output and may precipitate acute circulatory failure in patients with cardiovascular disease, particularly constrictive pericarditis. When particular caution is required Special care is needed in administering thiopental sodium to patients with the following conditions:- hypovolaemia, severe haemorrhage, burns, cardiovascular disease, status asthmaticus, myasthenia gravis, adrenocortical insufficiency (even when controlled by cortisone), cachexia, raised intracranial pressure and raised blood urea.

g. thyrotoxicosis, myxoedema and diabetes. Use in hepatic and renal disease Thiopental sodium is metabolised primarily by the liver so doses should be reduced in patients with hepatic impairment. Barbiturate anaesthetics should be used with caution in severe renal disease.

Reduced doses are also indicated in the elderly and in patients who have been premedicated with narcotic analgesics. 5) and in underlying disease Thiopental sodium has been shown to interact with sulphafurazole. Reduced initial doses may be required to achieve adequate anaesthesia, but repeat doses may also be necessary to maintain anaesthesia.

Patients taking long-term medications such as aspirin, oral anticoagulants, oestrogens, MAOIs and lithium may need to adjust the dose or stop therapy prior to elective surgery. Patients with diabetes or hypertension may need to adjust their therapy before anaesthesia.

Increased doses Increased doses may be necessary in patients who have either a habituation or addiction to alcohol or drugs of abuse. Under these circumstances it is recommended that supplementary analgesic agents are used. Extravasation Extravasation causes local tissue necrosis and severe pain.

This can be relieved by application of an ice pack and local injection of hydrocortisone. The 5% w/v solution is hypertonic and may cause pain on injection and thrombophlebitis. Accidental intra-arterial injection Accidental intra-arterial injection of thiopental sodium causes severe arterial spasm and an intense burning pain around the injection site.

Thiopental is contra-indicated in respiratory obstruction, acute asthma, severe shock and dystrophia myotonica. Administration of any barbiturate is contra- indicated in porphyria. Care should also be exercised with severe cardiovascular diseases, severe respiratory diseases and hypertension of various aetiology.

Patients with hypersensitivity reactions to barbiturates.