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|Thiopental Sodium

Thiopental Sodium

Trade Names:
Pentothal
- Powder for injection 2% (20 mg/mL)
- Powder for injection 2.5% (25 mg/mL)

Mechanism of Action

Pharmacology

Depresses CNS to produce hypnosis and anesthesia without analgesia.

Pharmacokinetics

Distribution

Thiopental is 80% bound to plasma proteins. The partition coefficient is 580.

Metabolism

Thiopental is degraded in liver and to a smaller extent, kidney and brain. The concentrations in spinal fluid is slightly less than in plasma.

Elimination

Thiopental is eliminated in urine and t _½ is 3 to 8 hr.

Indications and Usage

Induction of anesthesia; supplementation of other anesthetic agents; IV anesthesia for short surgical procedures with minimal painful stimuli; induction of hypnotic state; control of convulsions and increased intracranial pressure (IV administration); induction of preanesthetic sedation or basal narcosis (PR administration).

Contraindications

Hypersensitivity to barbiturates; variegate or acute intermittent porphyria; absence of suitable veins for IV administration; status asthmaticus.

Patients undergoing rectal surgery; lesions of bowel.

Dosage and Administration

IV 25 to 75 mg; observe for 60 sec.

IV 50 to 75 mg slowly q 20 to 40 sec until anesthesia is established then 25 to 50 mg prn or continuous infusion of 0.2% or 0.4%.

IV 5 to 6 mg/kg then 1 mg/kg prn.

IV 5 to 8 mg/kg then 1 mg/kg prn.

IV 3 to 4 mg/kg then 1 mg/kg prn.

IV 75 to 125 mg; may need 125 to 250 mg over 10 min.

IV 2 to 3 mg/kg/dose; repeat prn.

IV 1.5 to 3.5 mg/kg.

IV 1.5 to 5 mg/kg/dose; repeat prn.

IV 100 mg/min slowly with patient counting backwards or as infusion of 50 mL/min of 0.2% solution.

PR 1 g/34 kg (30 mg/kg).

PR 1 g/22.5 kg (44 mg/kg) (max, 3 to 4 g for adults weighing over 90 kg).

PR 25 mg/kg/dose; if not sedated within 15 to 20 min, may repeat with single dose of 15 mg/kg/dose (max, 1.15 g for children over 34 kg).

PR 15 mg/kg/dose; if not sedated within 15 to 20 min, may repeat with single dose of less than 7.5 mg/kg/dose.

Storage/Stability

Store at room temperature, protected from light.

Drug Interactions

May cause additive barbiturate effects and increase risk of apnea.

May increase frequency and severity of neuromuscular excitation and hypotension.

May extend barbiturate effects or effects may be achieved at lower doses.

May enhance barbiturate effects.

Incompatibility

Tubocurarine, succinylcholine, or other acid pH solutions.

Laboratory Test Interactions

Drug may falsely elevate results.

Drug may falsely elevate results.

Adverse Reactions

Cardiovascular

Myocardial depression; arrhythmias.

CNS

Delirium, headache; amnesia; seizures.

Dermatologic

Rash.

GI

Abdominal pain; rectal irritation; diarrhea; cramping; rectal bleeding (rectal suspension).

Respiratory

Apnea; laryngospasm; bronchospasm; hiccoughs; sneezing; coughing.

Miscellaneous

Thrombophlebitis; pain at injection site; salivation; shivering.

Precautions

Pregnancy

Category C ; readily crosses placental barrier.

Lactation

Excreted in breast milk.

Elderly

At increased risk of prolonged or potentiated hypnotic effects. Dosage reduction is required when administered rectally.

Renal Function

Use drug with caution in patients with renal disease. Dosage reduction is required (75% of normal dose if Ccr is less than 10 mL/min).

Hepatic Function

Use drug with caution in patients with hepatic disease.

Special Risk Patients

Use drug with caution in patients with severe cardiovascular, respiratory, renal, hepatic, or endocrine disease, hypotension or shock, conditions in which hypnotic effects may be prolonged or potentiated, potential rectal surgery (rectal suspension), or presence of inflammatory, ulcerative, bleeding, or neoplastic lesions of lower bowel (rectal suspension).

Repeated doses

May result in prolonged drug effect because of accumulation.

Overdosage

Symptoms

Respiratory depression, hypotension, shock, apnea, occasional laryngospasm, coughing, respiratory difficulties.

Patient Information

• Instruct patient to notify health care provider of any signs of hypersensitivity to barbiturates.
• Inform patient to avoid alcohol or other CNS depressants for 24 hr.
• Advise patient that drug can continue to impair abilities for 24 hr following administration and caution patient to avoid driving or performing other tasks requiring mental alertness.