Benzodiazepine Dose Equivalence: Lorazepam to Diazepam
1 mg of lorazepam is equivalent to 5 mg of diazepam. Therefore, for a 5 mg dose of diazepam, the equivalent dose of lorazepam would be 1 mg 1.
Pharmacological Basis for Equivalence
Benzodiazepines vary in their potency, duration of action, and pharmacokinetic properties. When determining equivalence between different benzodiazepines, these factors must be considered:
Potency Comparison
- Lorazepam is approximately 5 times more potent than diazepam 1
- This established equivalence ratio of 1:5 (lorazepam:diazepam) has been consistently documented in clinical studies
Pharmacokinetic Differences
Onset of Action:
- Diazepam has a more rapid onset of action compared to lorazepam
- Clinical effects begin more quickly with diazepam than lorazepam 1
Duration of Action:
- Lorazepam has a longer duration of effect than diazepam at equivalent doses
- Clinical effects and amnesia last longer following lorazepam administration 1
Route of Administration Considerations:
- Diazepam is better absorbed orally than intramuscularly
- Lorazepam has more consistent absorption across different routes of administration 1
Clinical Applications of Equivalence
The 1:5 equivalence ratio between lorazepam and diazepam is applied in various clinical scenarios:
Anxiety Management
- For sedation/anxiolysis, lorazepam 0.05-0.10 mg/kg IV (maximum single dose: 5 mg) is used 2
- This corresponds to diazepam doses of approximately 0.25-0.5 mg/kg IV
Seizure Management
- For status epilepticus, lorazepam 0.1-0.3 mg/kg IV (maximum: 10 mg per dose) is recommended 2
- Comparative studies have shown that lorazepam 4 mg is roughly equivalent to diazepam 10 mg in seizure control efficacy 3
Special Populations
- Elderly or frail patients should receive lower doses (e.g., 0.25-0.5 mg lorazepam) 2
- Patients with respiratory conditions like COPD require reduced doses due to risk of respiratory depression 2
Important Clinical Considerations
Safety Monitoring
- Monitor for respiratory depression, especially when combining with opioids or other CNS depressants 2
- Be prepared to provide respiratory support regardless of administration route
- Flumazenil may be administered to reverse life-threatening respiratory depression, though it may precipitate seizures in dependent patients 2
Practical Application
When converting between these medications:
- 5 mg diazepam = 1 mg lorazepam
- 10 mg diazepam = 2 mg lorazepam
- 20 mg diazepam = 4 mg lorazepam
Potential for Dependence
Both medications have similar abuse liability profiles in individuals with histories of recreational benzodiazepine use 4, though their pharmacokinetic differences may influence their clinical utility in different scenarios.