Objective To elucidate micafungin PK in children with confirmed invasive candidiasis or candidemia.

Methods Patients, age 3 weeks to 15 years (N = 12), received micafungin (100 mg/day if >40 kg in weight and 2 mg/kg/day if <40 kg) for at least 14 days. Plasma concentration-time profiles were determined after the initial dose (Day 1) and on the final day of treatment. PK parameters were estimated for two populations (Group I: <5 years of age and Group II: ⩾5 years).

Results Mean ages of Group I (n = 7) and II (n = 5) were 48 weeks (range 3–208) and 13 years (range 11–15), respectively, with mean weights of 5.2 kg (range 1.7–9.6) and 39.1 kg (range 25.5–46.7), respectively. See table for mean (±SD) PK parameters. Mean half-life (∼10–15 hours) and clearance did not vary over the study duration. Clearance in children <5 years was broadly similar to those ⩾5 years. Furthermore, the Cmax and AUC0-24 for the two populations were broadly similar.

Conclusions While younger children often achieve lower Cmax, have faster clearance, and lower drug exposure than older children, the dosing regimen in this study (2 mg/kg) provided appropriate drug exposure across the two age groups. Furthermore, there was no accumulation of micafungin following daily dosing for 14 or 28 days beyond that expected for a drug with linear PK.