[Midazolam in anesthesiology]

Abstract

Midazolam (MDZ) (8-chloro-6(2-fluoropheny 1)-1-methyl-4H-imidazol-[1,5a] [1,4]benzodiazepine) is an "annelated" benzodiazepine (BZDs) synthetized in 1976, characterized differently with the "classical" BZDs by a five-membered heterocycle fused on position 1,2 of the diazepine nucleus. This fused imidazol ring modifies the properties inherent in the "classical" BZDs in at the least three aspects: solubility, metabolisation and the stability in aqueous solution. MDZ, having similar properties with the "classical" benzodiazepines, has better local tolerance, faster onset of action, greater plasmatic clearance, shorter half-life elimination (1.7-2.4 hr) with no active metabolites. With a bioavailability of 92% (IV), 82-91% (IM) and 50-52% "per os", the CNS effects of MDZ are similar in all three ways. In anesthesiology we can administer MDZ as an anesthetic premedication ("per os", IM or IV), anesthetic induction and maintenance and IV sedation in locorregional anesthetic procedures or diagnostic and therapeutic explorations. MDZ has a great safety margin, moderate respiratory and cardiovascular effects and lacks of teratogenic or embryotoxic effects.