• Posaconazole trough levels [ Time Frame: Day 10; 20; 30 ] [ Designated as safety issue: No ]
  

• adverse events monitoring [ Time Frame: entire study ] [ Designated as safety issue: Yes ]
  

At this moment itraconazole is the drug of first choice in the prophylaxis of fungal infections in children with CGD. Breakthrough fungal infections while on itra-conazole prophylaxis are described in literature indicating the need for a drug with a broader antifungal spectrum. PSZ might provide in this need. PSZ may also have a clinical safety and tolerability advantage over other antifungal agents. Because PSZ is metabolized through phase II glucuronidation it is less common to be subject to drug interactions. PSZ is known to be a CYP3A4 inhibitor, but does not inhibit other CYP enzymes, therefore it may exhibit fewer drug interactions as compared with other azole antifungal agents.

Treatment of children is still off-label use. No data have been published to date on the exposure of PSZ in children under the age of 8 or in children with CGD. There is an urgent need to study the use of PSZ in these young children. Furthermore, the current regimen for antifungal prophylaxis requires a three times daily administration of PSZ. For this specific purpose less complex dosing schedules are warranted thus defining the need to examine a twice daily schedule.

As the tolerability and pharmacokinetics are unknown in patients under the age of 8 years and only limited data are available for age groups 8 to 16 years, we propose a feasibility study of a twice daily regimen of PSZ prophylaxis in CGD patients. With this information available we can suggest a dosage for future prophylaxis in this patient group.