It is used for the induction of general anaesthesia or anaesthesia of short duration, reduction of raised intracranial pressure if ventilation; status epilepticus. It is also used for hypnosis and for the control of convulsive states.
General (Intravenous) anesthetics
Thiopental, a barbiturate, is used for the induction of anesthesia prior to the use of other general anesthetic agents and for induction of anesthesia for short surgical, diagnostic, or therapeutic procedures associated with minimal painful stimuli. Thiopental is an ultrashort-acting depressant of the central nervous system which induces hypnosis and anesthesia, but not analgesia. It produces hypnosis within 30 to 40 seconds of intravenous injection. Recovery after a small dose is rapid, with some somnolence and retrograde amnesia. Repeated intravenous doses lead to prolonged anesthesia because fatty tissues act as a reservoir; they accumulate Pentothal in concentrations 6 to 12 times greater than the plasma concentration, and then release the drug slowly to cause prolonged anesthesia
Thiopental binds at a distinct binding site associated with a Cl- ionopore at the GABAA receptor, increasing the duration of time for which the Cl- ionopore is open. The post-synaptic inhibitory effect of GABA in the thalamus is, therefore, prolonged.
It is administered by intravenous route only. Induction of general anesthesia: (by intravenous injection) usually as a 2.5% (25mg/ml) solution; in fit pre-medicated adults,initially 100-150mg (reduced in elderly or debilitated), followed by further quantity if necessary according to response after 30-60 seconds; or upto 4mg/kg (max. 500mg). Children: induction 2-7mg/kg. Raised intracranial pressure,by intravenous injection,1.5-3 mg/kg repeated as required. Status epilepticus (only if other measure fail),by intravenous injection as a 2.5% (25mg/kg) solution,75-125mg as a single dose. For inducing anesthesia,100-150mg as a 2.5% or occasionally 5% solution is injected over 10 to 15 seconds; if relaxation has not occurred in about 30 seconds a further 100-150mg may be given. Injection should be given with patients in the recumbent position and care should be taken to see none of this solution is injected outside the vein,as it may cause tissue nacrosis. For longer procedures repeated or continuous administration may be used. It may be administered by rectum as a basal anesthetic in a dose of 40mg per kg body weight,with a maximum of 2g dissolved in about 30ml of water for injection.
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 thiopental sodium with metoclopramide, sulfisoxazole, aspirin, meprobamate, probenecid and other highly protein bound drugs.
Thiopental sodium for injection is contraindicated in patients with severe respiratory embarrassment,hypersensitivity to barbiturates status asthmaticus,variegate or acute intermittent porphyria,and inflammatory conditions of the mouth,jaw,and neck and in the absence of suitable veins for intravenous administration. Thiopental sodium for injection is also relatively contraindicated in severe cardiovascular disease,hypotension or shock,and conditions in which the hypnotic effect may be prolonged or potentiated,i.e. excessive premedication,Addison's disease,hepatic or renal dysfunction,myxedema,increased blood urea,severe anemia and myasthenia gravis.
Hypersensitivity reactions to barbituates,including Thiopental sodium have been reported. Adverse reactions include respiratory depression,myocardial depression,cardiac arrhythmias,prolonged somnolence and recovery,sneezing,coughing,bronchospasm, laryngospasm and shivering. Anaphylactoid reactions to It have been reported. Symptoms e.g. urticaria,bronchospasm,vasodilation and oedema should be managed by conventional means. Rarely immune haemolytic anaemia with renal failure and radial nerve palsy has been reported.
Moderate doses of It injection do not usually cause fetal depression when used in pregnancy. Small amounts of It may appear in the milk of nursing mothers following administration of large doses.
Overdosage may occur from too rapid or repeated administration. Too rapid injection may be followed by an alarming fall in blood pressure even to shock levels. Apnoea, occasional laryngospasm, coughing and other respiratory difficulties with excessive or too rapid injections may occur. In the event of suspected or apparent overdosage, the agent should be discontinued.
Store at controlled room temperature of 15° C to 30° C. Solutions should be freshly prepared and used immediately. Any portion of the contents remaining should be discarded.
Thiopental 500 mg injection: Each box contains 1 vial of 500 mg Thiopental Sodium for Injection (a sterile mixture of Thiopental Sodium and anhydrous Sodium Carbonate as a buffer) & 1 ampoule of 10 ml Water for Injection.
Thiopental 1 gm injection: Each box contains 1 vial of 1 gm Thiopental Sodium for Injection (a sterile mixture of Thiopental Sodium and anhydrous Sodium Carbonate as a buffer) & 2 ampoules of 10 ml Water for Injection.
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