BACKGROUND: Invasive fungal infections cause excessive morbidity and mortality in premature neonates and severely ill infants.METHODS: Safety and efficacy outcomes of micafungin were compared between prematurely and non-prematurely born infants <2 years of age. Data were obtained from all completed phase I-III clinical trials with micafungin that had enrolled infants (<2 years of age) that were listed in the Astellas Clinical Study Database. Demographics, adverse events, hepatic function tests and treatment success data were extracted and validated by the Astellas biostatistical group for all micafungin-treated patients, <2 years of age, using the unique patient identifier.RESULTS: One-hundred and sixteen patients included in 9 clinical trials, 48% premature [birth weight (BW) <2500 g and/or gestational age <37 weeks], 52% non-premature, received ≥ 1 dose of micafungin. Among premature patients, 14.5% were low BW (1500-2499 g), 36.4% very low BW (1000-1499 g) and 49.1% extremely low BW (<1000 g). Ninety patients (78%) completed the studies; 13 [11% (4 premature)] died. Significantly more non-premature than premature patients discontinued treatment (P = 0.003). Treatment-related adverse events were recorded in 23% of patients with no difference between groups. More extremely low BW (n = 4, 15%) and very low BW (n = 8, 40%) infants experienced treatment-related adverse events than low BW (n = 0) and there was no relation to micafungin dose or duration. For a subgroup of 30 patients with invasive candidiasis, treatment success was achieved in 73% in both premature and non-premature groups. Prophylaxis was successful in 4/5 non-premature hematopoietic stem cell transplant patients.CONCLUSION: Micafungin has a safe profile in premature and non-premature infants with substantial efficacy.