[Intramuscular premedication with midazolam in infants and children]

The useful intramuscular premedication dose of midazolam was determined in 100 children divided up in three age groups: one month to three years, 3 to 10 years, 10 to 15 years. All biometric parameters were normal for the age, and comparable between similar age groups. Haemodynamic and respiratory parameters were not altered by the premedication. The reduction in anxiety, as assessed by the child's behaviour, was good or excellent in more than 85% of cases from all age groups; it was proportional to the dose used. The doses that had, for equivalent reductions in anxiety as assessed by the chi-square test, the least hypnotic effect, were: 0.5 mg X kg-1 before three years of age, 0.4 mg X kg-1 for the 3 to 10 yr olds, and 0.25 mg X kg-1 for the 10 to 15 yr olds. This fall in dose with age, quite usual in paediatrics, was not unexpected. The level of consciousness, one hour after surgery, was always normal. No undesirable side-effect was observed. These results, together with its physical, chemical and pharmacodynamic characteristics, make midazolam a choice drug for intramuscular premedication in children, with a foreseeable use in day-care anaesthesia. The unexpected finding of an age-dependent dissociation between the reduction in anxiety and the hypnotic effect is discussed in the light of a study carried out in the adult and recent data from the literature.