What is the onset of action for sodium thiopental after IV administration?

What is the onset of action for sodium thiopental after IV administration?

• A. 5-10 minutes
• B. 30-60 seconds
• C. 2-3 minutes
• D. 10-20 seconds

Answer: (B)

Onset of action after IV administration is extremely rapid because sodium thiopental is highly lipid-soluble, so it quickly crosses the blood–brain barrier and rapidly redistributes into the brain. When given as a rapid IV bolus, the brain concentration rises within seconds to a minute, producing loss of consciousness. Clinically, this translates to induction of anesthesia occurring roughly 30 to 60 seconds after the injection. Injection rate and patient factors can tweak the exact moment, but the characteristic window for rapid induction with thiopental is on the order of tens of seconds to about a minute.

Onset of action after IV administration is extremely rapid because sodium thiopental is highly lipid-soluble, so it quickly crosses the blood–brain barrier and rapidly redistributes into the brain. When given as a rapid IV bolus, the brain concentration rises within seconds to a minute, producing loss of consciousness. Clinically, this translates to induction of anesthesia occurring roughly 30 to 60 seconds after the injection. Injection rate and patient factors can tweak the exact moment, but the characteristic window for rapid induction with thiopental is on the order of tens of seconds to about a minute.