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Pharmacokinetic interactions between midazolam and propofol: an infusion study
1Department of Anaesthesia and Intensive Care, Chinese University of Hong Kong.
British Journal of Anaesthesia
|January 1, 1994
Summary
The combination of midazolam and propofol for intravenous sedation does not appear to enhance sedation by increasing free plasma drug concentrations. Further research is needed to understand the synergistic effects of these anesthetic agents.
Area of Science:
- Anesthesiology
- Pharmacology
- Clinical Pharmacy
Background:
- Midazolam and propofol are commonly used for intravenous sedation.
- Synergistic interactions between these drugs are clinically observed.
- The mechanism behind this synergism requires elucidation.
Purpose of the Study:
- To investigate if the synergistic effect of combined midazolam and propofol is due to increased free plasma concentrations.
- To quantify changes in free plasma levels of midazolam and propofol when co-administered.
Main Methods:
- A pharmacokinetic study involving six patients receiving propofol followed by midazolam, and six patients receiving midazolam followed by propofol.
- Constant plasma concentrations of each drug were maintained using model-controlled syringe pumps.
- Free drug concentrations were measured in venous blood samples before and after the administration of the second drug.
Main Results:
- Co-administration of propofol did not significantly alter the free plasma concentration of midazolam (P = 0.32).
- Co-administration of midazolam did not significantly alter the free plasma concentration of propofol (P = 0.94).
- Neither drug's free plasma concentration changed significantly upon addition of the other.
Conclusions:
- The synergistic interaction between midazolam and propofol in i.v. sedation is not solely explained by an increase in the free plasma concentration of either drug.
- The underlying mechanism for the observed synergism remains to be identified.