Diazepam IV Equivalence to Lorazepam 1mg IV
The equivalent dose of diazepam IV to lorazepam 1mg IV is 5mg diazepam IV. This 5:1 ratio is supported by clinical evidence and pharmacological properties of these benzodiazepines 1.
Pharmacological Comparison
Potency and Onset
- Lorazepam is approximately 5 times more potent than diazepam on a mg-per-mg basis
- Diazepam has a faster onset of action (1-2 minutes) compared to lorazepam (1-5 minutes)
- Lorazepam has a longer duration of action (60-120 minutes) compared to diazepam (15-60 minutes) 2
Clinical Equivalence Evidence
- Studies have established that diazepam 10mg is equivalent to lorazepam 2-2.5mg for sedative effects 1
- This supports the 5:1 ratio (diazepam:lorazepam) for clinical dosing
Clinical Applications
Status Epilepticus Management
- For status epilepticus, IV lorazepam 0.1mg/kg (max 4mg) is equivalent to IV diazepam 0.2-0.3mg/kg (max 10mg) 3
- Lorazepam may be preferred over diazepam for status epilepticus due to:
- Longer duration of anticonvulsant activity
- Less redistribution
- Higher efficacy for seizure cessation (RR 1.24; 95% CI 1.03-1.49) 4
Sedation for Procedures
- For procedural sedation, the 5:1 ratio is also applicable:
- Lorazepam 1mg IV ≈ Diazepam 5mg IV
- Lorazepam 2mg IV ≈ Diazepam 10mg IV 3
Important Clinical Considerations
Dose Adjustments
- Elderly patients: Reduce dose by 20% or more in patients over 60 years 2
- Hepatic/renal impairment: Both medications require dose reduction, but lorazepam may be preferred in renal impairment 3
Safety Monitoring
- Monitor respiratory status, level of sedation, and vital signs with either medication
- Respiratory depression risk increases when combined with opioids
- Have flumazenil available for reversal of severe respiratory depression 2
Administration Differences
- Diazepam causes more venous irritation than lorazepam 1
- Lorazepam has better IM absorption compared to diazepam, which has erratic IM absorption 3
Pitfalls to Avoid
Underdosing: Inadequate dosing of benzodiazepines in status epilepticus is associated with progression to refractory status epilepticus 5
Rapid administration: Administering either medication too quickly increases risk of respiratory depression and hypotension
Failure to account for duration: While diazepam acts more quickly, its anticonvulsant effect is shorter, potentially requiring additional doses or follow-up with longer-acting anticonvulsants 3
Ignoring drug interactions: Both medications have synergistic effects with other CNS depressants, particularly opioids 2
The 5:1 ratio (diazepam:lorazepam) provides a reliable clinical guideline for dosing equivalence when converting between these two benzodiazepines for most adult patients.