What is the equivalent dose of Ativan (lorazepam) to Klonopin (clonazepam) 0.5mg twice daily (bid) in an adult patient with anxiety or seizure disorder?

Benzodiazepine Dose Equivalency: Clonazepam to Lorazepam

Clonazepam 0.5 mg twice daily (total 1 mg/day) is equivalent to lorazepam 1 mg twice daily (total 2 mg/day), using the standard 2:1 conversion ratio where 1 mg clonazepam equals 2 mg lorazepam. 1

Standard Conversion Ratio

• The established conversion ratio is 2:1 between lorazepam and clonazepam, meaning clonazepam 1 mg = lorazepam 2 mg, and therefore clonazepam 0.25 mg = lorazepam 0.5 mg. 1
• This conversion applies most reliably for anxiolysis, sedation, and acute agitation management. 1

Practical Application for Your Dose

• Clonazepam 0.5 mg BID (1 mg total daily) converts to lorazepam 1 mg BID (2 mg total daily). 1
• This maintains equivalent therapeutic effect while accounting for the different potencies of these benzodiazepines. 1

Critical Pharmacokinetic Differences to Consider

Onset and Duration:

• Lorazepam has a faster onset of action with peak effect at 3-5 minutes IV, making it more suitable for acute situations. 1
• Clonazepam has a dramatically longer half-life (30-40 hours) compared to lorazepam, affecting dosing frequency and accumulation risk. 1

Metabolism:

• Lorazepam is directly conjugated and eliminated, undergoing different metabolic pathways than clonazepam. 1
• Clonazepam has 90% bioavailability after oral administration. 1

Important Clinical Caveats

Side Effect Profile Differences:

• Morning sedation, early morning motor incoordination, confusion and memory dysfunction, risk of falls, and potential worsening of sleep apnea are more common with clonazepam due to its longer half-life. 1
• Use clonazepam with particular caution in patients with neurodegenerative disorders, obstructive sleep apnea, or underlying liver disease. 1

Respiratory Depression Risk:

• Both medications can cause respiratory depression, especially when combined with opioids or other CNS depressants, requiring monitoring of oxygen saturation and preparation to provide respiratory support if needed. 1

Patient-Specific Factors:

• Women may require higher doses than men to achieve the same clinical effect. 1
• Patient factors such as age, liver function, and concomitant medications affect metabolism of both drugs. 1

When Converting Between These Medications

If switching from clonazepam to lorazepam, expect patients to notice the shorter duration of action, potentially requiring more frequent dosing or experiencing breakthrough symptoms between doses due to lorazepam's shorter half-life. 1

If switching from lorazepam to clonazepam, taper gradually using 0.25 mg decrements per week to avoid withdrawal symptoms, as clonazepam can be successfully discontinued without major withdrawal if reduced slowly. 2