Clinical Pharmacokinetics

, Volume 6, Issue 2, pp 89–105 | Cite as

Clinical Pharmacokinetics of Oxazepam and Lorazepam

  • David J. Greenblatt


Oxazepam and lorazepam are 3-hydroxy benzodiazepine derivatives used as sedatives and anxiolytics. The major metabolic pathway for both compounds involves conjugation to glucuronic acid at the 3-position, followed by urinary excretion of the inactive glucuronide metabolite.

Oxazepam has been administered to humans by the oral route only. Usual ranges for kinetic parameters are: elimination half-life, 5 to 15 hours; volume of distribution, 0.6 to 2.0L/kg; clearance, 0.9 to 2.0ml/min/kg. Age and liver disease have a minimal influence on oxazepam kinetics, but renal disease is associated with a prolonged half-life and increased volume of distribution.

Typical kinetic values for lorazepam are: elimination half-life, 8 to 25 hours; volume of distribution, 1.0 to 1.3L/kg; clearance, 0.7 to 1.2ml/min/kg. Lorazepam clearance is somewhat reduced in old age, but liver disease has a minimal effect on clearance. Oral and intramuscular lorazepam are rapidly absorbed, with systemic availability averaging 90 % or more.

Both oxazepam and lorazepam are extensively bound to plasma protein, but the free fraction for lorazepam (8 to 12%) is greater than that for oxazepam (2 to 4%).


Cimetidine Clinical Pharmacokinetic Oxazepam Disulfiram Acute Viral Hepatitis 


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Copyright information

© ADIS Press Australasia Pty Ltd. 1981

Authors and Affiliations

  • David J. Greenblatt
    • 1
  1. 1.Division of Clinical Pharmacology, Departments of Psychiatry and MedicineTufts University School of Medicine and New England Medical Center HospitalUSA

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