Thiopental

Major Uses

Thiopental is a type of intravenous anesthetic used to induce anesthesia prior to inhalation maintenance. It may also be used as a sole agent for minor, non-painful procedures. It has a rapid onset of action and an ultra-short duration.

Thiopental is approved by the Food and Drug Administration for use in many different species of animals, including cats and dogs. It is a controlled substance and should only be administered in a veterinary setting.

Common Precautions

Thiopental causes sedation and respiratory depression. Careful monitoring is essential. Adverse reactions may cause various symptoms, including prolonged somnolence, abnormal heart rhythms, low respiratory rate, bronchospasm, excitement, and others.

Thiopental is not for use in animals with severe cardiovascular compromise, shock, intracranial space-occupying lesions, head trauma, or liver disease. It should be used with considerable caution in animals with kidney disease.

Because sight hounds have a reduced ability to metabolize thiopental, the drug should not be used to induce or maintain anesthesia in these animals. Doing so risks prolonged recovery and other complications.

If thiopental is accidentally injected outside of the vein, it may cause a skin slough due to the drug's high alkalinity. Thiopental is known to interact with numerous other supplements and medications, including cephapyrin, dimenhydrinate, glycopyrrolate, hydromorphone, Ringer's solution, Lactated Ringers, amikacin, insulin, levorphanol, meperidine, atropine, benzylquinamide, metaraminol, chlorpromazine, codeine, morphine, norepinephrine, prochlorperazine, diphenhydramine, ephedrine, penicillin G, succinylcholine, promazine, promethazine, and tetracycline. It should be noted that drugs with an acidic pH should not be mixed with thiopental solutions.

Thiopental should not be used in animals with a known allergy or hypersensitivity to the drug. Overdose of thiopental is potentially fatal and should be considered an emergency. Any known or suspected overdose outside a veterinary facility should be reported to a veterinarian right away.

Storage

Thiopental should be stored in the original packaging, at room temperature, and away from children and animals.

Administration

Thiopental is available as a powder for reconstitution with sterile water to an injectable solution. The powder is available in amounts of 250 mg, 400 mg, 500 mg, 1 g, 2.5 g, and 5 g. The addition of sterile water makes either a 2.0% or 2.5% solution containing 20 mg/ml and 25 mg/ml, respectively.

Only a licensed veterinarian should administer thiopental. The medication is titrated intravenously to effect. In unpremedicated dogs, the typical dose is 5 to 12.5 mg/lb (10 to 25 mg/kg). In cats, the dose is 4.5 mg to 5.5 mg/lb (9 to 11 mg/kg) IV. Premedicants will affect the required dose of thiopental. Thiopental is typically used as a single dose. Two doses of this medication should not be given at once.

Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.