From the Guidelines
When converting from intravenous (IV) midazolam to oral (PO) diazepam (Valium), use a conversion ratio of approximately 1:2, as midazolam is 1.5–3.5 times more potent than diazepam 1. This means that 1 mg of IV midazolam is roughly equivalent to 2 mg of oral diazepam. For example, if a patient is receiving 2 mg of IV midazolam, they would need approximately 4 mg of oral diazepam. Some key points to consider when making this conversion include:
- The timing of the switch, since midazolam has a shorter half-life compared to diazepam
- Administering the first dose of diazepam as the effect of the last midazolam dose begins to wane
- Monitoring the patient closely after conversion for signs of either oversedation or withdrawal
- Considering factors such as liver function, age, and concomitant medications that may necessitate dose adjustments
- Remembering that both medications are benzodiazepines with potential for dependence, so any long-term use should include a tapering plan, as noted in the context of endoscopic sedation 1. It's also important to note that the major side effects of both medications include respiratory depression, and that dose reduction is required in debilitated or elderly patients 1.
From the FDA Drug Label
Midazolam is a potent sedative agent that requires slow administration and individualization of dosage. Clinical experience has shown midazolam to be 3 to 4 times as potent per mg as diazepam
The conversion from IV midazolam to PO valium (diazepam) should be done with caution.
- Dose conversion: considering midazolam is 3 to 4 times as potent as diazepam, the dose of diazepam should be 3 to 4 times higher than the dose of midazolam.
- Key consideration: the potency difference between the two drugs and the individual patient's response to sedation. 2
From the Research
IV Midazolam to PO Valium Conversion
- The conversion from IV midazolam to PO valium (diazepam) is a common practice in clinical settings, particularly when transitioning patients from intravenous to oral medication regimens 3.
- However, there is limited direct evidence on the specific conversion ratio from IV midazolam to PO valium, as most studies focus on the comparison of midazolam with diazepam in different routes of administration, such as intravenous, intramuscular, or rectal 4, 5, 6.
- A study on the pharmacokinetics and tolerability of nasal versus intravenous midazolam in healthy volunteers found that the bioavailability of intranasal midazolam was 82%, which may be relevant when considering the conversion from IV to oral routes 7.
- In a pediatric intensive care setting, a study evaluated the effectiveness of institutionally established calculations for transitioning continuous IV midazolam to enteral benzodiazepines, including diazepam, and found that the conversion calculations maintained Withdrawal Assessment Tool-Version 1 scores equal to or less than preconversion values 3.
- When comparing the effectiveness of parenteral midazolam and diazepam in treating prehospital seizures, a study found that midazolam was superior to diazepam in stopping seizures without recurrence during the prehospital encounter 6.
Key Considerations
- The choice of conversion ratio from IV midazolam to PO valium should be based on individual patient factors, such as age, weight, and medical history, as well as the specific clinical context 3.
- Close monitoring of patients during the conversion process is essential to ensure that the desired therapeutic effect is achieved while minimizing the risk of adverse events 3.
- Further research is needed to establish evidence-based guidelines for the conversion from IV midazolam to PO valium, taking into account the pharmacokinetic and pharmacodynamic properties of both medications 4, 5, 7, 6.