Active ingredient: Thiopental - Brands, Medical Use, Clinical Data

Brands, Medical Use, Clinical Data

Drug Category

• Anesthetics, Intravenous
• Anticonvulsants
• GABA Modulators
• Hypnotics and Sedatives

Dosage Forms

• Powder for solution

Brands / Synonyms

Farmotal; Intraval; Nesdonal; Penthiobarbital; Pentothal; Pentothiobarbital; Robinax; Thiomebumal; Thionembutal; Thiopentobarbital; Thiopentobarbitone; Thiopentobarbituric acid; Thiopentone; Thiothal; Tiopentale; Tiopentale [Italian]; Trapanal

Indications

For use as the sole anesthetic agent for brief (15 minute) procedures, for induction of anesthesia prior to administration of other anesthetic agents, to supplement regional anesthesia, to provide hypnosis during balanced anesthesia with other agents for analgesia or muscle relaxation, for the control of convulsive states during or following inhalation anesthesia or local anesthesia, in neurosurgical patients with increased intracranial pressure, and for narcoanalysis and narcosynthesis in psychiatric disorders.

Pharmacology

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

Mechanism of Action

Thiopental binds at a distinct binding site associated with a Cl^- ionopore at the GABA_A 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.

Absorption

Rapidly absorbed.

Toxicity

Overdosage may occur from too rapid or repeated injections. Too rapid injection may be followed by an alarming fall in blood pressure even to shock levels. Apnea, occasional laryngospasm, coughing and other respiratory difficulties with excessive or too rapid injections may occur. Lethal blood levels may be as low as 1 mg/100 mL for short-acting barbiturates; less if other depressant drugs or alcohol are also present.

Biotrnasformation / Drug Metabolism

Primarily hepatic. Biotransformation products of thiopental are pharmacologically inactive and mostly excreted in the urine.

Contraindications

Absolute Contraindications

• Absence of suitable veins for intravenous administration,
• hypersensitivity (allergy) to barbiturates and
• variegate porphyria (South African) or acute intermittent porphyria.

Relative Contraindications

• Severe cardiovascular disease,
• hypotension or shock,
• conditions in which the hypnotic effect may be prolonged or potentiated ó excessive premedication, Addisonís disease, hepatic or renal dysfunction, myxedema, increased blood urea, severe anemia, asthma, myasthenia gravis, and
• status asthmaticus.

Diluents in Pentothal® Kits

Ready-To-Mix Syringes and Vials
(For preparing solutions of Thiopental Sodium for Injection, USP)

Do not use unless the diluent is clear and the bottle or vial seal or syringe package is undamaged.

Diluents in Pentothal Kits, Ready-to-Mix Syringes or Vials should not be used for fluid or sodium chloride replacement.

Drug Interactions

The following drug interactions have been reported with thiopental.