Diazepam Equivalent to 1 mg Lorazepam BID
The equivalent dose of diazepam to 1 mg lorazepam BID is 5 mg diazepam BID, based on the established potency ratio where 10 mg diazepam equals 2-2.5 mg lorazepam. 1
Conversion Ratio
- Lorazepam is approximately 2-2.5 times more potent than diazepam, meaning 1 mg lorazepam is equivalent to approximately 4-5 mg diazepam 1
- For practical clinical dosing, 10 mg diazepam equals 2-2.5 mg lorazepam, which translates to a 1:5 ratio (1 mg lorazepam = 5 mg diazepam) 1
- Therefore, 1 mg lorazepam BID converts to 5 mg diazepam BID 1
Critical Pharmacokinetic Differences to Consider
While the doses are equivalent in potency, these medications behave very differently in the body:
Onset and Duration
- Diazepam has a much faster onset (2-5 minutes IV, peaks at 2-3 minutes) compared to lorazepam (15-20 minutes IV with an 8-15 minute latent period) 2, 3
- Diazepam's clinical effect diminishes rapidly despite its long half-life, while lorazepam's effects increase and persist longer at 15-30 minutes 2, 3
- Diazepam's duration of action is 20-120 hours due to active metabolites, compared to lorazepam's 8-15 hours 2
Metabolism and Safety Profile
- Diazepam produces active metabolites that accumulate in renal failure, prolonging sedation unpredictably 2
- Lorazepam undergoes glucuronide conjugation without active metabolites, making it safer in hepatic and renal dysfunction 2
- This is why lorazepam is specifically recommended for patients with liver failure, renal failure, advanced age, or serious medical comorbidities 4
Dosing Adjustments for Special Populations
Elderly or Debilitated Patients
- Reduce diazepam dose by 50% or more (start with 2.5 mg instead of 5 mg BID) 2
- Reduce lorazepam dose by 20% or more (start with 0.8 mg instead of 1 mg BID) 2
- Elderly patients are significantly more sensitive to benzodiazepine sedative effects and have decreased clearance 5
Hepatic or Renal Dysfunction
- Lorazepam is preferred over diazepam in these patients due to lack of active metabolites 2
- Diazepam should be avoided or used with extreme caution in hepatic or renal failure due to unpredictable accumulation 2, 5
Common Clinical Pitfalls
- Do not assume equivalent dosing means equivalent clinical effect timing: diazepam acts faster but wears off quicker despite its long half-life 2, 3
- When combined with opioids, both medications require dose reduction due to synergistic respiratory depression 2
- Monitor for respiratory depression, especially with rapid administration or concurrent CNS depressants 5
- Avoid switching to diazepam in patients with hepatic or renal impairment who are stable on lorazepam 2
Specific Clinical Context Recommendations
For Alcohol Withdrawal Syndrome
- Long-acting benzodiazepines like diazepam are recommended for seizure prevention 4
- However, lorazepam is specifically recommended for patients with severe AWS, advanced age, liver failure, respiratory failure, or obesity 4
- Lorazepam dosing for AWS is 6-12 mg/day (typically divided into 1-4 mg every 4-8 hours), then tapered 4
For Status Epilepticus
- Lorazepam is more effective than diazepam for acute seizure control, with 76% efficacy versus 51% for diazepam with a single dose 6
- Lorazepam causes less respiratory depression (3% versus 15% with diazepam) 6
- Diazepam should be followed immediately by a long-acting anticonvulsant because seizures often recur within 15-20 minutes due to rapid redistribution 4