Barbiturates

Summary

Barbiturates are a class of medications that includes the drugs primidone and phenobarbital. They work by activating GABA receptors in the brain, which suppresses brain activity.

Clinically, barbiturates are used as sedative-hypnotics, especially in the context of anesthesia induction. They are also used for the treatment of seizures.

Common side effects of barbiturates include sedation, ataxia, respiratory depression, and teratogenicity. They also carry a high potential for abuse and addiction.

Barbiturates have many drug interactions, as they affect liver enzymes involved in the metabolism of other medications. Notably, they can decrease the effectiveness of oral contraceptives. Patients taking barbiturates should avoid alcohol.

Key Points

• Barbiturates
  • Drug Names
    • -barbital Ending
      • Phenobarbital (Luminal)
      • Secobarbital (Seconal)
      • Pentobarbital (Nembutal)
      • Thiopental (Pentothal)
      • Amobarbital (Amytal)
    • Primidone (Mysoline)
  • Mechanism
    • Activate GABA receptors
      • Depress the sensory cortex, decrease motor activity, alter cerebellar function
  • Clinical Use
    • Treat seizures
      • Often called antiepileptic, anticonvulsant, or antiseizure
      • Can be used to treat
        • Tonic-clonic seizures (grand mal seizures)
        • Partial seizures
        • Status epilepticus
    • Sedation
      • As CNS depressants, barbiturates are often used for their sedative properties
        • Anesthesia induction
        • Medically-induced coma
        • Insomnia (old practice, not common use anymore)
  • Side Effects
    • Sedation/Drowsiness
    • Ataxia (loss of coordination)
    • Respiratory depression
    • High abuse potential
      • High risk for tolerance and dependence
      • Addictive
      • Phenobarbital is a schedule IV controlled substance, while several other barbiturates are schedule II.
    • Teratogenic
      • Pregnancy Risk Category D
      • Avoid in pregnancy
  • Interactions and Precautions
    • Lots of drug interactions
      • Barbiturates are CYP enzyme inducers, meaning they accelerate the metabolism activity of enzymes in the liver. Any other medications that are also metabolized in the liver will have an accelerated breakdown and reduced effectiveness, including
        • Warfarin
        • Steroids
        • Theophylline
    • Decreases effectiveness of oral contraceptives
      • Consider other forms of birth control to prevent pregnancy
    • Avoid alcohol
      • Other CNS depressants should also be avoided, including opioids, antihistamines, and benzodiazepines.