Pharm

Benzodiazepine

search

Benzodiazepine, Sedative-Hypnotic, Benzodiazepine Metabolism

  • See Also
  1. Benzodiazepine Overdose
  • Indications
  • Outpatient
  1. Sedation in surgical, Medical and Psychiatric procedures
  2. Seizure disorder
  3. Alcohol Withdrawal and withdrawal from other drugs
  4. Anxiety Disorder
    1. Consider limiting to short-term stabilization until SSRI or SNRI (e.g. Venlafaxine) takes effect
    2. Adjunct to Cognitive Behavioral Therapy and other Anxiety Management
  5. Insomnia
    1. Consider alternative agents and methods (Trazodone, Melatonin, CBT-I, Sleep Hygiene)
    2. Consider Benzodiazepine Receptor Agonist instead (e.g. Ambien)
  6. Muscle spasm
    1. Consider alternative agents and methods (e.g. Flexeril, NSAIDs, back Exercises, physical therapy)
  • Contraindications
  1. Myasthenia Gravis
  2. Acute narrow-angle Glaucoma
  3. Substance Abuse (relative contraindication)
  • Mechanism
  1. Potentiates activity of gamma-aminobutyric acid (GABA)
  2. GABA is an inhibitory neurotransmitter in the CNS
    1. Muscle relaxant
    2. Anticonvulsant
    3. Anxiolytic
    4. Anti-aggressiveness
    5. Sedation
  • Precautions
  1. Benzodiazepines have significant risks
    1. Double the risk of Motor Vehicle Accidents, and falls (and Hip Fractures) in the elderly
    2. Double the risk of COPD exacerbations
  2. Benzodiazepine misuse and abuse is common
    1. Hospital admissions for Benzodiazepine Abuse have increased three-fold since the early 2000s
    2. Alprazolam is among the most addictive Benzodiazepines (responsible for 10% of drug-misuse related visits to the ED)
  3. Avoid combining Benzodiazepines if possible
    1. Risk of falls, memory problems, excessive sedation
    2. In some cases, occasional as needed dosing of a short acting Benzodiazepine in a user of a long acting Benzodiazepine may be appropriate
      1. Frequent as needed dosing should prompt re-evaluation with consideration of increasing the long-acting Benzodiazepine dose
    3. Non-Benzodiazepine sedatives (e.g. Ambien) can have additive effects with Benzodiazepines
  4. References
    1. (2014) Presc Lett 21(8): 45
    2. Zigman (2012) J Psychopharmacol 26: 1507-11 [PubMed]
  • Advantages
  1. Rapid onset of action
    1. Anxiolytic effect within 1-2 days
  2. Tolerance develops rapidly to adverse effects
  3. Tolerance does not develop for Anxiolytic effect
  4. Few Drug Interactions
  5. Good safety profile
  • Preparations
  1. Long Acting Benzodiazepines
    1. Chlordiazepoxide (Librium)
    2. Diazepam (Valium, Valrelease)
    3. Flurazepam (Dalmane)
    4. Chlorazepate (Tranxene)
    5. Clonazepam (Klonopin)
    6. Quazepam (Doral)
    7. Halazepam (Paxipam)
  2. Medium Acting Benzodiazepines
    1. Lorazepam (Ativan)
    2. Temazepam (Restoril)
  3. Short acting Benzodiazepines
    1. Oxazepam (Serax)
    2. Alprazolam (Xanax)
    3. Triazolam (Halcion)
    4. Estazolam (Prosom)
    5. Midazolam (Versed)
  • Absorption
  1. Preparations with most rapid absorption
    1. Diazepam (Valium)
    2. Clorazepate
    3. Alprazolam (Xanax) taken sublingually
  2. Preparations with slowest absorption
    1. Oxazepam (Serax)
    2. Co-administration of Benzodiazepine with medication
      1. Maalox
      2. Gelusil
  • Metabolism
  1. Renal Excretion
  2. Hepatic Metabolism
    1. Microsomal oxidation
    2. Conjugation by glucuronyl transferases
  3. Metabolic pathways
    1. Clonazepam metabolizes to 7-aminoclonazepam
    2. Alprazolam metabolizes to Alpha-hydroxyalprazolam
    3. Chlordiazepoxide metabolizes to Oxazepam (via Norchlordiazepoxide, Demoxepam, Nordiazepam)
    4. Medazepam metabolizes to Oxazepam (via Nordiazepam) and Diazepam
    5. Diazepam metabolizes to Oxazepam (via Nordiazepam) and Temazepam
    6. Temazepam metabolizes to Oxazepam
    7. Agents that metabolize to Oxazepam via nordiazepam
      1. Diazepam
      2. Demoxepam
      3. Halazepam
      4. Chlorazepate
      5. Prezapam
  4. References
    1. Valentine (1996) J Anal Toxicol 20(6): 416-24 +PMID:8889678
  • Dosing
  • Strategies
  1. Initiate treatment with low dose Benzodiazepine
    1. Prevent symptoms completely by using a regular regimen
    2. Escalate dose slowly, no more often than every 2 weeks
    3. Maintain lowest effective dose for several months
    4. Start with 50% of typical dose in at risk cohorts
      1. Elderly
      2. Hepatic dysfunction
      3. Renal dysfunction
  2. Tapering dose
    1. Periodically attempt to lower dose or ideally, titrate off completely
    2. Indications for prolonged taper periods (2-4 weeks per dose step-down)
      1. Higher Benzodiazepine doses
      2. Longer duration of Benzodiazepine use
      3. Short-acting Benzodiazepines (e.g. Alprazolam, Lorazepam)
    3. Example taper protocol
      1. Decrease dose by 25% for 1 week (2-4 weeks if prolonged taper indicated) THEN
      2. Decrease dose by 25% for 1 week (or 2-4 weeks if prolonged taper indicated) THEN
      3. Decrease dose by 10% per 1 week (or 2-4 weeks if prolonged taper indicated) until off
    4. Change to longer half-life drug if symptom breakthrough
      1. Example: Switch from Xanax to Klonopin
  • Dosing
  • Equivalent to Valium 60 mg (for withdrawal)
  1. High Potency Benzodiazepines
    1. Alprazolam (Xanax) 6 mg
    2. Clonazepam (Klonopin) 24 mg
    3. Lorazepam (Ativan) 12 mg
  2. Low Potency Benzodiazepines
    1. Chlordiazepoxide (Limbitrol) 150 mg
    2. Flurazepam (Dalmane) 90 mg
    3. Halazepam (Paxipam) 240 mg
    4. Oxazepam (Serax) 60 mg
    5. Temazepam (Restoril) 60 mg
  1. Pregnancy Category: D
  2. Lactation: Not allowed
  • Adverse Effects
  1. Drug Dependence
    1. Risk Benzodiazepine Withdrawal (Seizures may occur, especially if underlying Seizure disorder)
  2. Sedation
  3. Nausea
  4. Blood dyscrasia
  5. Anterograde amnesia
  6. Cognitive Impairment
  7. Respiratory depression
  8. Hyponatremia or Syndrome of Inappropriate Antidiuretic Hormone (SIADH)
  • Monitoring
  • Consider in patients on longterm therapy
  1. Complete Blood Count
  2. Liver Function Tests
  • References
  1. Tasman (1997) Psychiatry, Saunders, p. 1641-6 [PubMed]
  2. Katzung (1989) Pharmacology, Lange, p. 264-7 [PubMed]