What dose of lorazepam (Ativan) is equivalent to 2.5mg of midazolam (Versed)?

Midazolam to Lorazepam Conversion

2.5mg of midazolam (Versed) is equivalent to 1mg of lorazepam (Ativan). 1

Pharmacological Basis for Conversion

• Lorazepam is more potent than midazolam, with lorazepam being approximately 2-2.5 times more potent than midazolam 1
• Midazolam has a faster onset of action (1-2 minutes IV) compared to lorazepam (15-20 minutes IV) 1
• Midazolam has a shorter elimination half-life (3-11 hours) compared to lorazepam (8-15 hours) 1
• Both medications work through activation of GABA-A neuronal receptors in the brain, providing anxiolytic, amnestic, sedating, and anticonvulsant effects 1

Clinical Dosing Considerations

• Standard IV loading dose of midazolam is 0.01-0.05 mg/kg compared to lorazepam's 0.02-0.04 mg/kg (≤ 2 mg) 1
• Maintenance dosing for midazolam is 0.02-0.1 mg/kg/hr compared to lorazepam's 0.02-0.06 mg/kg q2-6hr or 0.01-0.1 mg/kg/hr 1
• When converting between these medications, consider that midazolam requires more frequent dosing due to its shorter duration of effect (15-80 minutes) 2
• Elderly patients are significantly more sensitive to the sedative effects of both benzodiazepines and require dose reductions 1

Special Considerations

• Patients with hepatic impairment require dose reductions for both medications due to decreased clearance 2, 3
• When either medication is combined with opioids, dose reductions are necessary due to synergistic respiratory depression 2
• Lorazepam has no active metabolites, while some benzodiazepines (though not specifically midazolam) may have active metabolites that can prolong sedation 1
• Midazolam is more lipid-soluble than lorazepam, resulting in quicker onset of sedation 1

Common Pitfalls

• Oversedation occurs more frequently with lorazepam compared to midazolam (14% vs 6% of assessment times) 4
• Both medications can cause respiratory depression and hypotension, especially when administered with other cardiopulmonary depressants 1
• Rapid administration of either medication increases the risk of respiratory depression 3
• Re-sedation may occur as effects wear off, requiring continued monitoring beyond the initial sedation period 3

Clinical Applications

• For acute agitation management, midazolam may be preferred due to its rapid onset 3
• For longer-term sedation, lorazepam may be more cost-effective despite potential for oversedation 4, 5
• The predicted emergence time from sedation after a 72-hour infusion is significantly longer with lorazepam compared to midazolam 6