Diazepam Equivalent for Alprazolam 4mg
The equivalent dose of diazepam for alprazolam 4mg is approximately 40mg of diazepam, based on a 1:10 potency ratio.
Benzodiazepine Equivalency
The conversion between alprazolam and diazepam is based on established potency ratios from clinical comparison studies:
- Alprazolam is approximately 10 times more potent than diazepam 1, 2
- Studies demonstrate that alprazolam 1.5-3 mg/day produces equivalent anxiolytic effects to diazepam 15-30 mg/day 2
- This establishes a consistent 1:10 conversion ratio (1 mg alprazolam = 10 mg diazepam) 1
Calculation for 4mg Alprazolam
Using the 1:10 potency ratio:
Important Clinical Considerations
Pharmacokinetic Differences
- Alprazolam has a half-life of 12-19 hours with peak levels at 0.7-2.1 hours 3, 1
- Diazepam has a longer half-life and different distribution pattern 4
- These differences mean the clinical effects will not be identical despite equivalent anxiolytic potency 3
Dosing Frequency Adjustments
- Alprazolam's shorter half-life typically requires 3-4 times daily dosing 3
- Diazepam's longer half-life may allow less frequent dosing
- When converting, consider dividing the total daily diazepam dose (40mg) into 2-3 administrations rather than matching alprazolam's dosing schedule 3, 4
Critical Safety Warning
- 4mg of alprazolam is at the upper limit of recommended daily dosing (0.5-4.0 mg/day) 3
- This high dose suggests either tolerance, inadequate treatment, or inappropriate prescribing
- 40mg of diazepam is a substantial dose that carries significant risks of sedation, respiratory depression, and falls, particularly in elderly patients 5
- Concomitant use with other CNS depressants dramatically increases risk 5
Conversion Protocol
When switching between these medications:
- Taper the alprazolam while initiating diazepam rather than abrupt substitution to minimize withdrawal risk 3
- Monitor closely for oversedation, respiratory depression, and cognitive impairment 5
- Consider that 40mg diazepam may produce more prolonged sedation than the patient experienced with alprazolam 4