This is a prospective (study following patients forward in time), open-label (all people know the identity of the intervention), multi-center (conducted in more than one center) observational study to examine the correlation between a sufficient blood concentration of itraconazole and disappearance of a fever (defeverscence) when itraconazole injection is administered for resolving unknown neutropenic fever of participants who are given itraconazole oral solution as a prophylaxis under general treatment conditions. The recommended dose of the drug will be 200 milligram (mg), which will be administered intravenously, twice daily for 2 days (a total of 4 doses) and then 200 mg once daily for 12 days. After the administration for a total of 14 days, itraconazole oral solution 200 mg (which is equivalent to 20 ml) twice daily will be continued for a total of 14 days until clinically significant neutropenia is resolved.
The purpose of this observational study is to investigate whether a sufficient concentration of itraconazole can influence disappearance of a fever (defeverscence) when intravenous (into the vein) itraconazole is administered for resolving unknown neutropenic fever of participants who are given itraconazole oral solution as a prophylaxis under general treatment conditions.