Benzodiazepine Dose Conversion: Clonazepam to Lorazepam
Clonazepam 1mg BID (2mg total daily) converts to approximately 2mg of lorazepam per day, typically dosed as 1mg twice daily. 1
Standard Conversion Ratio
The established conversion ratio is 0.5mg clonazepam = 1mg lorazepam, meaning lorazepam is approximately twice as potent as clonazepam. 1
Step-by-Step Conversion Algorithm
Initial Calculation
- Total daily clonazepam dose: 1mg × 2 = 2mg/day 1
- Multiply by 2 for initial lorazepam equivalent: 2mg × 2 = 4mg/day lorazepam 1
Critical Half-Life Adjustment
- Adjust downward by 50% to account for clonazepam's longer half-life (30-40 hours vs lorazepam's shorter duration): 4mg ÷ 2 = 2mg/day lorazepam 1, 2
- This adjustment is essential because clonazepam's extended half-life provides more sustained coverage 1
Dosing Schedule
- Divide into 2-3 doses per day: 1mg lorazepam every 12 hours (or 0.5-1mg every 8-12 hours) 1, 3
- Start with every 6-8 hour dosing initially, then adjust the interval based on clinical response 1
- The largest dose should be given at bedtime 3
Critical Monitoring Requirements
Monitor closely for:
- Breakthrough anxiety or withdrawal symptoms (indicating underdosing) 1
- Oversedation or respiratory depression (indicating overdosing) 1, 2
- Rebound withdrawal symptoms post-treatment, which occur more commonly with lorazepam than longer-acting benzodiazepines 4
Titration strategy:
- Adjust dose by 10-20% increments based on clinical response 1
- Maximum single dose should not exceed 4-5mg 1, 3
- Maximum total daily dose is 4mg/24 hours in standard adults, 2mg/24 hours in elderly 2, 3
Special Population Adjustments
For elderly or debilitated patients:
- Start with 0.5mg lorazepam twice daily maximum 1, 2
- Reduce to 0.25-0.5mg doses due to increased fall risk and sensitivity 2, 5
Common Pitfalls to Avoid
Do not use the simple 1:2 ratio without the half-life adjustment - this is the most critical error, as it would result in overdosing (4mg/day instead of 2mg/day). 1
Watch for paradoxical agitation - occurs in approximately 10% of patients on benzodiazepines. 2, 5
Avoid abrupt discontinuation - use gradual taper if lorazepam has been used beyond 1-2 weeks to minimize withdrawal risk. 2, 3
Monitor for respiratory depression when combined with other CNS depressants, opioids, or alcohol - ensure respiratory support is available. 1, 2
Be aware of cognitive impairment risk - regular benzodiazepine use leads to tolerance, addiction, depression, and cognitive dysfunction; use the lowest effective dose. 2, 5