PLASMA-CONCENTRATIONS OF MIDAZOLAM AFTER .4. NASAL OR RECTAL ADMINISTRATION IN CHILDREN

Midazolam is used frequently for premedication in children, preferably by non-parenteral administration. We have compared plasma concentrations of midazolam after nasal, rectal and i. v. administration in 45 children (aged 2-9 yr; weight 10-30 kg) undergoing minor urological surgery. General anaesthesia consisted of spontaneous respiration of halothane and nitrous oxide in oxygen via a face mask. After administration of atropine and fentanyl iv., children were allocated randomly to receive midazolam 0.2 mg kg-1 by the nasal, rectal or iv. route. In the nasal group, children received 50% of the dose of midazolam in each nostril. In the rectal group, midazolam was given rectally via a cannula. Venous blood samples were obtained before and up to 360 min after administration of the drug. Plasma concentrations of midazolam were measured by gas chromatography and electron capture detection. After nasal and rectal administration, midazolam Cmax was 182 (SD 57) ng ml-1 within 12.6 (5.9) min, and 48 (16) ng ml-1 within 12.1 (6.4) min, respectively. Rectal administration resulted in smaller plasma concentrations. In the nasal group, a plasma concentration of midazolam 100 ng ml-1 occurred at about 6 min. After 45 min, the concentration curves after i. v. and nasal midazolam were similar.