What is the equivalent dose of lorazepam (Ativan) for a patient taking clonazepam (Klonopin) 2 mg?

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Clonazepam 2 mg to Lorazepam Equivalent Dose

Clonazepam 2 mg is approximately equivalent to lorazepam 2-2.5 mg based on sedative potency.

Benzodiazepine Equivalency

  • The standard conversion ratio is approximately 1:1 to 1:1.25 (clonazepam:lorazepam), meaning 2 mg of clonazepam equals roughly 2-2.5 mg of lorazepam for sedative effects 1.

  • This equivalency is based on comparative sedative potency studies, though it's important to recognize that clonazepam and lorazepam differ significantly in their pharmacokinetic profiles beyond just potency 1.

Critical Pharmacokinetic Differences

While the doses may appear equivalent, these medications behave very differently in clinical practice:

  • Clonazepam has a much longer elimination half-life (30-40 hours) compared to lorazepam, which affects dosing frequency and withdrawal risk 2.

  • Lorazepam has a duration of action of 1-24 hours, which is considerably shorter than clonazepam's sustained effect 3.

  • Clonazepam reaches maximum plasma concentrations within 1-4 hours after oral administration with 90% bioavailability 2.

Important Clinical Considerations When Converting

Do not perform abrupt substitution. When switching between these benzodiazepines:

  • Clonazepam should be tapered gradually by 0.25 mg per week when discontinuing after intermediate-term use to avoid withdrawal symptoms including anxiety, tremor, insomnia, nausea, sweating, tachycardia, headache, and muscle aches 4.

  • Lorazepam withdrawal can cause marked rebound insomnia and significant increases in tension and anxiety, particularly on the third night after discontinuation 5.

  • The longer half-life of clonazepam means withdrawal symptoms may be delayed compared to lorazepam 2, 5.

Common Pitfalls to Avoid

  • Do not assume equivalent dosing means equivalent clinical effect - clonazepam's longer duration may provide more sustained coverage, while lorazepam requires more frequent dosing 3, 1.

  • Be aware that both medications can cause significant side effects including morning sedation, confusion, memory dysfunction, and motor incoordination, with clonazepam potentially causing these effects for longer periods due to its extended half-life 2, 5.

  • In elderly patients, reduce lorazepam doses by 20% or more due to reduced clearance 3.

  • Monitor for respiratory depression risk, especially when combined with other CNS depressants or in patients with underlying respiratory disease 3.

References

Research

Comparison of the actions of diazepam and lorazepam.

British journal of anaesthesia, 1979

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Guideline

Intravenous Lorazepam Dosing and Administration Guidelines

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

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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