Thiontal 500 mg/vial (IV Injection)

Indications

• Sole anesthetic agent for brief (15 minutes) procedures
• Induction of anesthesia prior to administration of other anesthetic agents
• Supplement for regional anesthesia
• Hypnosis during balanced anesthesia with other agents
• Control of convulsive states
• Neurosurgical patients with increased intracranial pressure
• Narcoanalysis and narcosynthesis in psychiatric disorders

Composition

• Thiopental 500 mg injection
• Thiopental 1 gm injection
• Sterile mixture of Thiopental Sodium and anhydrous Sodium Carbonate as a buffer
• Ampoule of 10 ml Water for Injection

Pharmacology

• Ultrashort-acting depressant of the central nervous system
• Induces hypnosis and anesthesia, but not analgesia
• Binds at a distinct binding site associated with a Cl- ionopore at the GABA receptor
• Increases the duration of time for which the Cl- ionopore is open
• Prolongs the post-synaptic inhibitory effect of GABA in the thalamus

Dosage & Administration

• Administered intravenously as a 2.5% w/v solution
• May be administered as a 5% w/v solution (500 mg in 10 ml)
• Premedication with atropine or scopolamine
• Test dose of 25 mg to 75 mg to assess tolerance
• Normal dosage for induction of anesthesia is 100 mg to 150 mg injected over 10 to 15 seconds
• Dosage adjustments based on patient's response, age, sex, and weight
• Special dosage considerations for adults, children, and elderly

Interaction

• Possible increase in difficulty in producing anaesthesia in patients taking alcohol or CNS depressants
• Additive action with other CNS depressants including sedatives, hypnotics, nitrous oxide or alcohol
• Increased hypotension and excitatory effects with phenothiazine antipsychotics
• Increased hypnotic effect with antipsychotic
• Decreased requirement of Thiontal with metoclopramide, sulfisoxazole, aspirin, meprobamate, probenecid and other highly protein bound drugs

Contraindications

• Absence of suitable veins for intravenous administration
• Hypersensitivity (allergy) to barbiturates
• Variegate porphyria (South African) or acute intermittent porphyria
• Status asthmaticus
• Severe cardiovascular disease
• Hypotension or shock
• Conditions in which the hypnotic effect may be prolonged or potentiated

Side Effects

• Hypersensitivity reactions
• Respiratory depression
• Myocardial depression
• Cardiac arrhythmias
• Hypotension
• Tachycardia
• Sneezing, coughing, bronchospasm, laryngospasm, and shivering
• Anaphylactic reactions

Pregnancy & Lactation

• Pregnancy Category C
• Potential fetal harm
• Crosses the placental barrier
• Small amounts may appear in the milk of nursing mothers

Precautions & Warnings

• Constant attendance by a person competent in anesthesia management
• Adequate facilities for support of respiration and circulation
• Caution in patients with preexisting hypotension or conditions where the hypnotic effect may be prolonged
• Potential habit-forming
• Availability of resuscitative and endotracheal intubation equipment and oxygen
• Administered by persons qualified in the use of anesthetics
• Avoid extravasations or intra-arterial injection

Overdose Effects

• Too rapid or repeated administration may lead to overdosage
• Alarming fall in blood pressure
• Apnoea, occasional laryngospasm, coughing, and other respiratory difficulties
• Discontinue the agent in case of suspected or apparent overdosage

Therapeutic Class

• General (Intravenous) anesthetics

Storage Conditions

• Store at controlled room temperature of 15°C to 30°C
• Freshly prepare solutions and use immediately
• Discard any remaining portion of the contents

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