Pharmacokinetics and the sedative effect of midazolam

The pharmacokinetics and their relation to the pharmacodynamic properties of midazolam, the first water-soluble benzodiazepine derivative, are reviewed. Pharmacokinetically, midazolam is a unique derivative among the benzodiazepines. After both oral and parenteral routes of administration, it has a fast absorption rate, and differing from older derivatives it is very rapidly excreted with a half-life of only about 2 h. A reasonably good correlation has been found with the plasma levels and clinical effects, indicating a fast but short clinical response. Midazolam appears to be a useful short-acting hypnotic having almost no residual effects the following morning. In anesthesiology both oral and parenteral drug forms can be used for premedication. In addition, it is a new alternative for inducing anesthesia when a slow induction time is chosen or its advantageous properties: good cardiovascular stability, transient and mild respiratory depression, low frequency of venous irritation, production of anterograde amnesia, and short duration of action (last-mentioned property in comparison with other benzodiazepines).