Intranasal midazolam pharmacokinetics in children during anesthesia — preliminary results

Human variability in CYP3A4 metabolism and CYP3A4-related uncertainty factors for risk assessment

CYP3A4 constitutes the major liver cytochrome P450 isoenzyme and is responsible for the oxidation of more than 50% of all known drugs. Human variability in kinetics for this pathway has been quantified using a database of 15 compounds metabolised extensively (>60%) by this CYP isoform in order to develop CYP3A4-related uncertainty factors for the risk assessment of environmental contaminants handled via this route. Data were analysed from published pharmacokinetic studies (after oral and intravenous dosing) in healthy adults and other subgroups using parameters relating primarily to chronic exposure [metabolic and total clearances, area under the plasma concentration-time curve (AUC)] and acute exposure (Cmax). Interindividual variability in kinetics was greater for the oral route (46%, 12 compounds) than for the intravenous route (32%, 14 compounds). The physiological and molecular basis for the difference between these two routes of exposure is discussed. In relation to the uncertainty factors used for risk assessment, the default kinetic factor of 3.16 would be adequate for adults, whereas a CYP3A4-related factor of 12 would be required to cover up to 99% of neonates, which have lower CYP3A4 activity.

Nasal versus oral midazolam for sedation of anxious children undergoing laceration repair

STUDY OBJECTIVE

To compare the efficacy and safety of a single dose of midazolam, as an oral solution of 0.5 mg/kg, or nasal drops of 0.25 mg/kg, in children undergoing emergency department laceration repair.

DESIGN

Double-blind, double-placebo, randomized trial. Children underwent standard wound care when judged to demonstrate a reduction in anxiety following study medication.

PARTICIPANTS

Fifty-eight patients between 1 and 10 years of age with uncomplicated lacerations judged to be anxious by emergency physicians.

RESULTS

An anxiety score and vital signs were recorded at routine intervals. Groups were comparable with respect to age, laceration characteristics, initial vital signs, and anxiety scores. Both groups demonstrated reductions (mean +/- SD) in anxiety scores over time (P < .05; maximum at 10 minutes; 1.2 +/- 0.9 mm for nasal and 0.8 +/- 1.3 for oral), with no significant differences between groups (repeat-measures ANOVA). Median observer-rated effectiveness using a visual analog scale (maximum effectiveness, 10 mm) was not significantly different between groups: nasal, 7.6 mm and oral, 6.9 (Mann-Whitney U test: minimum detectable difference, 0.7, with alpha = 0.05 and beta = 0.2). Complications were judged to be minor only, and were more frequent in the nasal group (5 of 28, 4 with nasal burning) versus 1 of 26 in the oral group. Time from midazolam to ED discharge was not significantly different between groups: nasal, 54 +/- 15 minutes and oral, 57 +/- 16 minutes.

CONCLUSION

A single dose of oral or nasal midazolam results in reduced anxiety and few complications in selected children undergoing laceration repair in the ED. The oral route was associated with fewer administration problems.