CNS

Barbiturates

CNS Medications

Mark this drug class

Examples

phenobarbitalthiopentalsecobarbital

Prefix / Suffix: -barbital

Physiology

GABA-A receptors regulate CNS inhibition. Barbiturates produce profound CNS depression by prolonging chloride channel opening.

Mechanism of Action

Bind GABA-A receptors and prolong chloride channel opening, causing significant CNS depression. At higher doses, directly open chloride channels.

Indications

  • Seizure disorders (phenobarbital)
  • Induction of anesthesia (thiopental)
  • Severe insomnia (rare today)

Side Effects / Adverse Effects

  • Severe respiratory depression
  • Profound sedation, coma
  • Hypotension
  • Dependence and tolerance
  • Stevens-Johnson syndrome (rare)

Contraindications

  • Severe respiratory disease
  • Porphyria
  • Pregnancy
  • History of substance abuse

Nursing Considerations

  • Narrow therapeutic index — monitor blood levels (phenobarbital)
  • Monitor respiratory and cardiovascular status closely
  • No specific reversal agent — supportive care only in overdose
  • Taper slowly — abrupt withdrawal can cause seizures and death
  • Strong CYP450 inducer — many drug interactions (reduces effectiveness of warfarin, OCPs, others)
  • Highly addictive — use only when other options fail

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Disclaimer: PharmPal Nurse is for education only and is not medical advice. Do not use it to diagnose, treat, prescribe, or make patient-care decisions; always verify with current drug references, your instructor, facility policy, and a licensed provider. In emergencies, call local emergency services.