Medicine & USMLE


  1. Ketamine
  2. Nitrous Oxide (N2O)
  3. Local Anesthetics
  4. Nondepolarizing Neuromuscular-blocking Drugs
  5. Succinylcholine
  6. Halothane and Fluranes
  7. Propofol
  8. Thiopental


Thiopental is a short-acting barbiturate that’s mainly used for the induction of anesthesia. Its high lipid solubility allows for a rapid onset but also a short duration of activity, as the thiopental is redistributed from the brain into the muscle and fat. Thiopental has notable side effects such as respiratory and CNS depression.

Key Points

  • Thiopental
    • Mechanism
      • Barbituate
        • These drugs work by activating the GABA channels in the brain, increasing the duration that the chloride channels remains open
      • High lipid solubility
        • Fast onset
          • Anesthetics must dissolve through lipid membranes in order to work, especially at the blood-brain barrier
        • Short duration of action
          • Because of redistribution into muscle and fat
    • Clinical Use
      • Used as an IV anesthetic
        • Thiopental’s fast onset and short duration of action make it useful in the induction of anesthesia
    • Side Effects
      • CNS depression
      • Respiratory depression