Benzodiazepine Dose Conversion: Clonazepam 3mg to Lorazepam
3mg of clonazepam (Klonopin) is approximately equivalent to 6mg of lorazepam (Ativan), using a 1:2 conversion ratio.
Conversion Rationale
The conversion between these benzodiazepines is based on their relative potencies and pharmacokinetic profiles:
- Clonazepam is approximately twice as potent as lorazepam on a milligram-per-milligram basis 1
- Studies comparing sedative effects demonstrate that diazepam 10mg equals lorazepam 2-2.5mg, and clonazepam has similar potency to diazepam, supporting the approximate 1:2 conversion ratio 1
- Using this conversion: 3mg clonazepam × 2 = 6mg lorazepam equivalent dose
Critical Pharmacokinetic Differences
When making this conversion, you must account for substantial differences in drug behavior:
- Clonazepam has a dramatically longer half-life (30-40 hours) compared to lorazepam's shorter duration 2, 3
- Clonazepam provides sustained coverage over 24+ hours, while lorazepam's clinical effects last up to 72 hours but require more frequent dosing 4
- Clonazepam reaches maximum plasma concentrations in 1-4 hours with 90% bioavailability 2
Practical Conversion Strategy
Do not simply substitute 6mg lorazepam as a single daily dose. Instead:
- Divide the equivalent 6mg lorazepam dose into 3-4 divided doses (1.5-2mg three to four times daily) to account for its shorter duration of action 5
- The maximum recommended lorazepam dose is 4mg in 24 hours for routine anxiety management in standard patients 5
- Start with a lower equivalent dose (4-5mg total daily) divided into multiple doses and titrate based on clinical response 3
Safety Considerations and Monitoring
Elderly or debilitated patients require dose reduction:
- Reduce lorazepam doses by 50% in elderly/debilitated patients (maximum 2mg in 24 hours) 5, 3
- For this population, start with 0.25-0.5mg doses 5
Monitor closely for withdrawal and side effects:
- Clonazepam discontinuation can cause immediate symptom relapse 2
- Common side effects after conversion include sedation, confusion, memory dysfunction, and motor incoordination 2, 3
- Women may require different dosing adjustments than men 3
Special population precautions:
- Use with extreme caution in patients with neurodegenerative disorders, obstructive sleep apnea, or liver disease 2, 3
- Dose adjustment necessary in renal impairment 5, 3
- Risk of respiratory depression in COPD patients 5
Common Pitfalls to Avoid
- Never abruptly switch from clonazepam to lorazepam - the long half-life of clonazepam means overlap and gradual transition is safer 3
- Do not give the full equivalent dose as a single daily dose - lorazepam requires divided dosing 5
- Avoid exceeding 4mg lorazepam daily in standard outpatient anxiety management without clear clinical justification 5
- Do not assume 1:1 conversion - this will result in dangerous underdosing 1