Barbiturate, Mephobarbital, Amobarbital, Pentobarbital, Secobarbital

  • Background
  1. Barbiturates are Sedative-Hypnotics that have been medically available since the early 1900s
  2. Other Sedative-Hypnotics (e.g. Benzodiazepines) were developed as an alternative to the adverse effects of Barbiturates
  3. Mechanism
    1. GABA A Receptor Agonist
      1. Other GABA A receptor agonists include Alcohol and Benzodiazepines
      2. Barbiturates have synergistic activity with Benzodiazepines
    2. BABA Receptor agonists result in prolonged duration of GABA channel opening
      1. Allows for Calcium influx
  4. Effects
    1. Sensation and motor function suppressed
    2. Cerebellum altered function
    3. Sedation
    4. Amnesia
  • Preparations
  1. Long-Acting Barbiturates (duration 10-12 hours)
    1. Phenobarbital
    2. Mephobarbital
  2. Short-Acting Barbiturates (duration 3-6 hours)
    1. Amobarbital
      1. Historically was used during psychoanalysis, and for determining dominant hemisphere before neurosurgery
    2. Pentobarbital
    3. Secobarbital
  3. Very-Short Acting Barbiturates (duration <3 hours)
    1. Methohexital
    2. Thiopental
      1. Has been used as induction agent in Rapid Sequence Intubation (rarely used)
        1. Consider for Increased Intracranial Pressure (Fastest lowering of ICP of any induction agent)
      2. Contraindicated in hypotensive patients or porphyria
      3. Risk of skin necrosis if infiltrates (highly alkalotic agent with pH 10)
  4. Propanediol Carbamates (Barbiturate-Like agents)
    1. Meprobamate