What is the conversion dose from Serax (oxazepam) to Lorazepam?

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Last updated: June 11, 2025View editorial policy

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From the Guidelines

When converting from Serax (oxazepam) to lorazepam, the equivalent dose ratio is approximately 15 mg of oxazepam to 1 mg of lorazepam, as supported by general medical knowledge and benzodiazepine potency comparisons. This means that a patient taking 30 mg of oxazepam would need approximately 2 mg of lorazepam for an equivalent therapeutic effect.

Key Considerations for Conversion

  • The conversion ratio is based on the relative potencies of the two medications, with lorazepam being more potent than oxazepam.
  • Individual responses to benzodiazepines can vary, so it's crucial to start with the lower equivalent dose and titrate as needed.
  • Both medications are benzodiazepines, but lorazepam has a longer half-life (10-20 hours) compared to oxazepam (5-15 hours), which is essential for dosing and monitoring.
  • According to 1, lorazepam dosing can be adjusted based on patient factors, such as elderly or debilitated status, where the dose is reduced to 0.25-0.5 mg (maximum 2 mg in 24 hours), highlighting the need for careful dose adjustment in vulnerable populations.

Monitoring and Safety

  • Patients should be monitored for withdrawal symptoms if switching from a higher dose of oxazepam to lorazepam, and the conversion should be done gradually under medical supervision.
  • Side effects to watch for include sedation, dizziness, and potential respiratory depression, especially if combined with other central nervous system depressants, as indicated by the general principles of benzodiazepine use and the guidelines for managing symptoms like anxiety or agitation 1.

From the Research

Conversion Dose from Serax (Oxazepam) to Lorazepam

  • The conversion dose from Serax (oxazepam) to lorazepam is not directly stated in the provided studies, but we can look at the typical kinetic values and dosages used in various studies to estimate a possible conversion.
  • A study from 1980 2 compared the efficacy and side effects of lorazepam, oxazepam, and temazepam as sleeping aids in psychogeriatric inpatients. The study used 2 mg of lorazepam and 30 mg of oxazepam, suggesting a possible ratio of 1:15 (lorazepam:oxazepam).
  • However, this ratio may not be applicable in all situations, and the optimal conversion dose may depend on various factors such as the individual patient's response, the specific condition being treated, and the route of administration.
  • Another study from 1981 3 provides information on the pharmacokinetics of oxazepam and lorazepam, including their elimination half-lives, volumes of distribution, and clearances. This information may be useful in estimating a conversion dose, but it would require additional data and calculations to determine a specific conversion ratio.
  • It's also worth noting that the studies provided do not offer a direct comparison of the potency of oxazepam and lorazepam, which would be necessary to determine an accurate conversion dose.

Key Points to Consider

  • The conversion dose from Serax (oxazepam) to lorazepam may vary depending on the individual patient and the specific condition being treated.
  • The typical kinetic values and dosages used in various studies may provide some guidance, but an accurate conversion dose would require additional data and calculations.
  • It's essential to consult with a healthcare professional to determine the optimal conversion dose and to ensure safe and effective treatment.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Clinical pharmacokinetics of oxazepam and lorazepam.

Clinical pharmacokinetics, 1981

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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