This study aims to estimate the pharmacokinetics (PK) of posaconazole (POS, MK-5592) intravenous (IV) and powder for oral suspension (PFS) formulations in pediatric participants \<2 years of age with invasive fungal infection (IFI).
Panel A: is undergoing treatment for possible, probable, or proven IFI known or suspected to be cause by fungal pathogens against which POS has demonstrated activity (which can include candidiasis)
Panel B: has an investigator-assessed diagnosis of possible, probable, or proven IFI known or suspected to be cause by fungal pathogens against which POS has demonstrated activity (and cannot include candidiasis)
Has a central line (eg, central venous catheter, peripherally-inserted central catheter) in place or planned to be in place before beginning IV study intervention.
Has a body weight of ≥500 g
Has received POS within 30 days before Day 1
Has cystic fibrosis, pulmonary sarcoidosis, aspergilloma, or allergic bronchopulmonary aspergillosis
Has a known hereditary problem of galactose intolerance, Lapp lactase deficiency, or glucose-galactose malabsorption
Has known or suspected active COVID-19 infection