What dose of diazepam is equivalent to 0.5mg of Ativan (lorazepam)?

Diazepam Equivalent Dosing to Lorazepam 0.5mg

10mg of diazepam is equivalent to 0.5mg of lorazepam (Ativan). 1

Benzodiazepine Equivalence Ratios

The equivalence between diazepam and lorazepam is based on their relative potency:

• Diazepam 10mg is equivalent to lorazepam 2-2.5mg 1
• Therefore, diazepam 10mg ÷ 5 = lorazepam 0.5mg

Pharmacological Differences Between Diazepam and Lorazepam

Understanding the differences between these medications helps explain why such different doses are required for equivalent effects:

• Potency: Lorazepam is approximately 5 times more potent than diazepam on a milligram-per-milligram basis 1
• Onset of action: Diazepam has a more rapid onset than lorazepam 1
• Duration of action: Lorazepam has a longer duration of action than diazepam 1
• Absorption differences: Diazepam is better absorbed orally than intramuscularly, while lorazepam has consistent absorption via both routes 1

Clinical Considerations When Substituting These Medications

When switching between these benzodiazepines, consider:

• Metabolism: Diazepam has active metabolites with long half-lives, while lorazepam is directly conjugated and eliminated 2
• Risk of accumulation: Diazepam may accumulate with repeated dosing due to its longer half-life and active metabolites 2
• Administration route: If using intramuscular route, lorazepam has more reliable absorption than diazepam 1
• Venous complications: Lorazepam IV administration is associated with fewer venous thrombosis complications than diazepam 1

Common Pitfalls When Converting Between Benzodiazepines

• Underestimating potency differences: Failing to account for the 5:1 potency ratio can lead to under or overdosing 1
• Not considering half-life: Diazepam has a much longer half-life than lorazepam, which affects dosing frequency 2
• Ignoring patient factors: Age, liver function, and concomitant medications can affect metabolism of both drugs 2
• Respiratory depression risk: Both medications can cause respiratory depression, especially when combined with other sedatives or opioids 2