Ativan to Klonopin Conversion
When converting from Ativan (lorazepam) to Klonopin (clonazepam), use a 1:0.5 ratio—meaning 1 mg of lorazepam is approximately equivalent to 0.5 mg of clonazepam. 1
Conversion Ratio and Dosing
- Standard equivalency: 1 mg lorazepam = 0.5 mg clonazepam 1
- For example, if a patient is taking lorazepam 2 mg daily, the equivalent clonazepam dose would be 1 mg daily 1
- This conversion is based on the relative potency differences between these two benzodiazepines, with lorazepam being approximately twice as potent as clonazepam on a milligram-per-milligram basis 1
Key Pharmacokinetic Differences
Duration of action differs substantially between these medications:
- Lorazepam has a duration of action up to 72 hours in the CNS 2
- Clonazepam has a duration of approximately 24 hours 2
- Both medications have high affinity for benzodiazepine receptors, but their clinical effects differ in onset and duration 2
Practical Switching Strategy
Direct substitution approach:
- Calculate the total daily lorazepam dose 1
- Divide by 2 to determine the equivalent clonazepam dose 1
- Clonazepam's longer half-life allows for less frequent dosing (typically twice daily vs. lorazepam's 3-4 times daily) 1, 3
- The longer duration may reduce interdose anxiety symptoms that can occur with shorter-acting benzodiazepines 4
Special Population Adjustments
Elderly or debilitated patients require dose reduction:
- Start with 0.25-0.5 mg clonazepam daily (maximum 2 mg/24 hours) 1
- These patients have increased sensitivity and fall risk requiring more conservative dosing 5, 1
Critical Monitoring Considerations
- Monitor for respiratory depression, especially if combined with other sedatives 1
- Watch for paradoxical agitation, which occurs in approximately 10% of patients on benzodiazepines 5, 1
- Clonazepam metabolism varies significantly based on CYP3A4 expression, with low expressers requiring substantially lower doses (about half) compared to normal expressers 6
Common Pitfalls to Avoid
- Do not assume 1:1 equivalency—this will result in overdosing, as clonazepam is less potent milligram-per-milligram 1
- Account for the longer half-life of clonazepam when timing doses; patients may not need as frequent administration 3, 2
- Tolerance and dependence develop with regular use of both medications; use the lowest effective dose 1
- If discontinuation is needed after prolonged use (>1-2 weeks), taper gradually by 0.25 mg per week to minimize withdrawal symptoms 1, 3