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Thiopental Dosage

Applies to the following strength(s): 500 mg ; 250 mg ; 400 mg ; 5 g ; 1 g ; 2.5 g ; 400 mg/g

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Usual Adult Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for Anesthesia

When used for induction in balanced anesthesia with a skeletal muscle relaxant and an inhalation agent:
The total dose can be estimated and then injected in two to four fractional doses. With this technique, brief periods of apnea may occur which may require assisted or controlled pulmonary ventilation. As an initial dose, 210 to 280 mg (3 to 4 mg/kg) is usually required for rapid induction in the average adult (70 kg).

When used as the sole anesthetic agent:
Moderately slow induction can usually be accomplished in the "average" adult by injection of 50 to 75 mg (2 to 3 mL of a 2.5% solution) at intervals of 20 to 40 seconds, depending on the reaction of the patient. Once anesthesia is established, additional injections of 25 to 50 mg can be given whenever the patient moves. The desired level of anesthesia can be maintained by injection of small repeated doses as needed or by using a continuous intravenous drip in a 0.2% or 0.4% concentration. With continuous drip, the depth of anesthesia is controlled by adjusting the rate of infusion.

Usual Adult Dose for Seizures

For the control of convulsive states following anesthesia (inhalation or local) or other causes, 75 to 125 mg (3 to 5 mL of a 2.5% solution) should be given as soon as possible after the convulsion begins. Convulsions following the use of a local anesthetic may require 125 to 250 mg given over a ten minute period.

Usual Adult Dose for Coma Induction

In neurosurgical patients, intermittent bolus injections of 1.5 to 3.5 mg/kg of body weight may be given to reduce intraoperative elevations of intracranial pressure, if adequate ventilation is provided.

Usual Adult Dose for Psychosis

For narcoanalysis and narcosynthesis in psychiatric disorders, premedication with an anticholinergic agent may precede administration of thiopental. After a test dose, thiopental is injected at a slow rate of 100 mg/min (4 mL/min of a 2.5% solution) with the patient counting backwards from 100. Shortly after counting becomes confused but before actual sleep is produced, the injection is discontinued. Allow the patient to return to a semidrowsy state where conversation is coherent. Alternatively, thiopental may be administered by rapid IV drip using a 0.2% concentration in 5% dextrose and water. At this concentration, the rate of administration should not exceed 50 mL/min.

Usual Pediatric Dose for Anesthesia

Induction anesthesia:
less than 1 month: 3 to 4 mg/kg intravenously
less than 1 year: 5 to 8 mg/kg intravenously
1 year to 12 years: 5 to 6 mg/kg intravenously
over 12 years: 3 to 5 mg/kg intravenously

Maintenance anesthesia:
1 year and older: 1 mg/kg intravenously as needed

Usual Pediatric Dose for Seizures

1 year or older: 2 to 3 mg/kg/dose intravenously, repeat as needed.

Usual Pediatric Dose for Head Injury

1 year or older: 1.5 to 5 mg/kg/dose intravenously; repeat as needed to control intracranial pressure - larger doses (30 mg/kg) to induce coma after hypoxic-ischemic injury do not appear to improve neurologic outcome.

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Precautions

Test Dose
It is advisable to inject a small "test" dose of 25 to 75 mg (1 to 3 mL of a 2.5% solution) of thiopental to assess tolerance or unusual sensitivity to thiopental, and pausing to observe patient reaction for at least 60 seconds. If unexpectedly deep anesthesia develops or if respiratory depression occurs, consider these possibilities: (1) the patient may be unusually sensitive to thiopental, (2) the solution may be more concentrated than had been assumed, or (3) the patient may have received too much premedication.

Premedication usually consists of atropine or scopolamine to suppress vagal reflexes and inhibit secretions. In addition, a barbiturate or an opiate is often given. Sodium pentobarbital injection is suggested because it provides a preliminary indication of how the patient will react to barbiturate anesthesia. Ideally, the peak effect of these medications should be reached shortly before the time of induction.

Dialysis

Data not available

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