Midazolam: kinetics and effects on memory, sensorium, and haemodynamics

Area of Science:

• Pharmacology
• Clinical Pharmacy

Background:

• Midazolam is a water-soluble benzodiazepine used for sedation.
• Understanding its pharmacokinetic and pharmacodynamic properties is crucial for safe and effective clinical use.

Purpose of the Study:

• To compare the pharmacokinetics of oral versus intravenous midazolam.
• To evaluate the effects of midazolam on hemodynamics, sensorium, and memory.

Main Methods:

• Eight healthy volunteers received 15 mg midazolam orally and intravenously in a randomized crossover design.
• Serial blood samples were collected for 12 hours to analyze midazolam levels.
• Hemodynamic parameters, sensorium, and memory (word lists) were assessed post-administration.

Main Results:

• Midazolam demonstrated rapid absorption but incomplete bioavailability (49%) and rapid elimination (t1/2,Z = 1.89 h).
• Intravenous midazolam caused a significant decrease in systolic blood pressure and drowsiness, with sensorium clearing in 2-3 hours.
• Oral midazolam showed similar but less pronounced effects, with peak impairment at 30 minutes.
• Memory acquisition was markedly impaired for at least 90 minutes after intravenous administration, with poorer recovery compared to sensorium scores.

Conclusions:

• Midazolam exhibits rapid absorption, incomplete bioavailability, and rapid elimination.
• Intravenous administration of midazolam can significantly reduce blood pressure and affect consciousness.
• The degree of memory impairment may not correlate directly with the level of consciousness after midazolam administration.