BENZODIAZEPINE

CLASSIFICATION:

Long Acting

• Flurazepam 50-100 t1/2(hrs)
• Diazepam 30-60 t1/2(hrs)
• Nitrazepam 30 t1/2(hrs)
• Flunitrazepam 15-25 t1/2(hrs)

Short-Acting 

• Temazepam with t1/2 8-12 hrs
• Benzodiazepine without anticonvulsant property.
• Triazolam with t1/2 2-3 hrs
• Midazolam 2 t1/2(hrs)
• Alprazolam 

MOA:

PHARMACOKINETICS:

Short-acting BZDs:

• Eg: Midazolam – IV or IM as an induction agent.
  • Rapid onset of action.
  • Quick drug clearance.
  • Causes anterograde amnesia, tachyphylaxis during high dose infusions.
  • Decreased cardiovascular effects as compared to propofol 
• Temazepam or oxazepam – Revives insomnia. 
  • At lower doses, relieves acute symptoms of anxiety, such as panic attacks & phobias.

Long-acting BZDs: 

• Slower onset of action following oral administration —-> Hence prolonged pharmacological action.
• Sedation.
• Prevents increased muscle tone of tetanus infection. 
• Metabolized in liver by dealkylation and hydroxylation.
• Excreted in urine as glucuronide conjugates.

ACTIONS:

• Antianxiety

Sedation: 

• Increasing dosage produce sleep & hence considerable as hypnotic. 
• I.V administration used extensively to produce conscious sedation during unpleasant procedures. 
• Eg: Diazepam & midazolam.
• Cardiovascular stability – IV diazepam 
• Midazolam potentiates propofol in co-induction technique.

Anticonvulsants: 

• Clonazepam & diazepam – Effective in status epilepticus.

Muscle relaxation: 

• Reduce muscle tone.

 Amnesia: 

• IV benzodiazepines produces antegrade amnesia. 
• Midazolam – Very intense for 20-30 minutes
• Lorazepam – Longer amnesia – 6 hr.

DRUGS:

• Inverse agonist of benzodiazepine receptor – Beta carboline.
• Benzodiazepine antagonist – Flumazenil

USES:

• As hypnotic –
  • Daytime sedation (Alprazolam)
• As anxiolytic.
• Antidepressant  (Alprazolam)
• As anticonvulsants, especially emergency control of status epilepticus  
  • To avoid future recurrence of seizure attacks Oral Diazepam 6 hourly is given.
• As centrally acting muscle relaxant.
• For anesthetic medication and IV anesthesia 
• Alcohol withdrawal in dependent subjects 
• Mostly given along with analgesics (NSAIDs|). 
• DOC in elderly & with liver disease.
  • Lorazepam, Oxazepam & Temazepam
• Spasmolytics.
• Anti-ulcer.

ADVERSE EFFECT:

• Dizziness, lassitude, vertigo, disorientation, amnesia, increased reaction time with motor incoordination, impairment of mental coordination occur. 
• Weakness, blurring of vision, dry mouth and urinary incontinence.

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