Pharm 101: Clonazepam

Class

Benzodiazepine

Pharmacodynamics

• Long-acting benzodiazepine
• Binds to GABA-A:
  • Potentiates GABAergic inhibition through hyperpolarisation
  • Increases frequency of chloride channel opening
  • Acts throughout the brain, but the distribution of different GABA-A receptor isoforms varies across the CNS

Pharmacokinetics

• Bioavailability > 80%
• Peak concentrations in 1-4 hours
• 86% protein bound
• Lipid soluble and crosses blood brain barrier effectively
• Extensively metabolised in liver to inactive metabolites
• Half life 12-56 hours

Clinical uses

• One of the most potent anticonvulsant agents known:
  • Absence seizures
  • Myoclonic seizures
  • Infantile spasms
• Sedative-hypnotic
• Anxiolytic

Adverse effects

• Sedation, especially on initiation of therapy
• Toxicity and adverse effects are similar to diazepam

Further Reading

• Nickson C. Status Epilepticus. LITFL