Bioassays for itraconazole blood levels: an interlaboratory collaborative study

Area of Science:

• Pharmacology
• Clinical Chemistry
• Mycology

Background:

• Accurate measurement of antifungal drug concentrations is crucial for effective treatment.
• Itraconazole and its active metabolite, hydroxy-itraconazole, are key antifungals requiring reliable bioassays.
• Inter-laboratory variability in bioassay results can impact clinical decision-making.

Purpose of the Study:

• To evaluate the correlation between different bioassay methods for quantifying itraconazole and hydroxy-itraconazole in human serum.
• To assess the consistency of antifungal activity measurements across multiple laboratories.
• To determine if various bioassay techniques can reliably indicate the relative antifungal potency of serum samples.

Main Methods:

• Duplicate bioassays were performed on 30 serum samples for itraconazole and hydroxy-itraconazole.
• Five independent laboratories participated, each employing a distinct bioassay methodology.
• Both itraconazole and hydroxy-itraconazole served as analytical standards in the assays.

Main Results:

• Quantitative variations were observed in the bioassay results across the different methods and laboratories.
• Despite variations, a sufficient correlation was found between the results obtained from the various bioassays.
• The bioassays consistently indicated the relative level of antifungal activity present in the tested serum samples.

Conclusions:

• Different bioassay methods demonstrate sufficient correlation for assessing itraconazole and hydroxy-itraconazole levels in serum.
• The chosen bioassay techniques can reliably indicate the relative antifungal activity, despite quantitative differences.
• These findings support the use of various bioassay methods for monitoring antifungal drug efficacy in clinical settings.