What is the equivalent dose of lorazepam (Ativan) when converting from clonazepam (Klonopin)?

Clonazepam to Lorazepam Dose Conversion

The standard conversion ratio is 0.5 mg clonazepam = 1 mg lorazepam (1:2 ratio), meaning lorazepam is approximately twice as potent as clonazepam. 1

Conversion Algorithm

Step 1: Calculate Equivalent Dose

• Multiply the total daily clonazepam dose by 2 to determine the equivalent lorazepam dose 1
• Example: Clonazepam 1 mg/day = Lorazepam 2 mg/day

Step 2: Adjust for Half-Life Differences

• Clonazepam has a 30-40 hour half-life versus lorazepam's 12 hour half-life 2, 3
• When converting from continuous IV midazolam (similar pharmacokinetics to clonazepam) to lorazepam, guidelines account for the sixfold longer half-life by dividing the 24-hour midazolam dose by 12 1
• For clonazepam to lorazepam conversion, divide the calculated equivalent lorazepam dose by 2-3 to account for the longer half-life of clonazepam 1

Step 3: Dosing Schedule

• Divide the total daily lorazepam dose into 2-4 divided doses (every 6-12 hours) 1
• Lorazepam reaches peak concentrations approximately 2 hours after oral administration 3
• Start with every 6-8 hour dosing initially, then adjust interval based on clinical response 1

Practical Conversion Examples

Example 1: Standard Conversion

• Clonazepam 0.5 mg twice daily (1 mg/day total)
• Initial lorazepam equivalent: 1 mg × 2 = 2 mg/day
• Adjusted for half-life: 2 mg ÷ 2 = 1 mg/day lorazepam
• Dosing: 0.5 mg lorazepam every 12 hours 1

Example 2: Higher Dose Conversion

• Clonazepam 2 mg/day
• Initial equivalent: 2 mg × 2 = 4 mg/day lorazepam
• Adjusted: 4 mg ÷ 2 = 2 mg/day lorazepam
• Dosing: 0.5-1 mg lorazepam every 6-8 hours 1

Critical Monitoring and Titration

First 48-72 Hours

• Monitor closely for breakthrough symptoms or oversedation 1
• Titrate dose by 10-20% based on clinical response 1
• Watch for withdrawal symptoms including anxiety, tremor, insomnia, tachycardia, and sweating 4

Ongoing Management

• Lorazepam reaches steady-state within 2-3 days 3
• Adjust dosing interval gradually: every 6h → every 8h → every 12h as tolerated 1
• Maximum single dose should not exceed 4-5 mg 1

Special Population Adjustments

Elderly or Debilitated Patients

• Start with 50% of the calculated equivalent dose 2, 5
• Initial dosing: 0.5-1 mg lorazepam twice daily maximum 1, 2, 5
• Increased sensitivity and fall risk require more conservative dosing 5

Hepatic Impairment

• Consider starting with lower equivalent doses (e.g., 0.5 mg lorazepam for 1 mg clonazepam) 2
• Lorazepam undergoes glucuronidation (not oxidative metabolism), making it safer in liver disease 3

Renal Impairment

• Dose adjustment may be necessary 2
• Monitor for accumulation of inactive glucuronide metabolites 3

Common Pitfalls to Avoid

Oversedation Risk

• Do not use the simple 1:2 ratio without adjusting for half-life differences 1
• Clonazepam's longer half-life means patients may have significant drug on board during conversion 2, 4

Withdrawal Symptoms

• Abrupt switching can precipitate benzodiazepine withdrawal 4
• Symptoms may be delayed due to clonazepam's long half-life 1
• Use gradual cross-titration over 1-2 weeks for patients on chronic therapy 4

Paradoxical Reactions

• Approximately 10% of patients experience paradoxical agitation with benzodiazepines 1, 5
• Monitor for increased anxiety, agitation, or confusion 1, 5

Respiratory Depression

• Monitor oxygen saturation, especially when combined with other CNS depressants 1, 5
• Have flumazenil available for reversal if needed, though it may precipitate seizures 1

Drug Interactions

• Reduce dose by 50% if combined with other CNS depressants 2
• Use caution with opioids, alcohol, or other sedatives 2
• Be aware of potential serotonin syndrome risk with SSRIs 1