Correlation of plasma levels of itraconazole with treatment response at 4 weeks in chronic dermatophytosis: Results of a randomized controlled trial.

BACKGROUND
Itraconazole in varying doses and duration is being frequently used for the management of dermatophytosis. There is a scarcity of studies on the bioavailability of various itraconazole brands available in the market.


AIMS AND OBJECTIVES
To determine the plasma concentration of itraconazole of various brands and its correlation with clinical efficacy in chronic dermatophytosis.


MATERIALS AND METHODS
One hundred patients with chronic dermatophytosis with age >18 years were studied at the outpatient clinic of our tertiary care hospital. Plasma itraconazole level was estimated on week 2 and week 4 after randomly dividing the patients into Group A, B, C who received cap itraconazole 100 mg twice a day of innovator, multinational, local generic brands, respectively for 4 weeks. Both efficacy (cure, partial cure or no cure), safety and recurrence were compared between three groups.


RESULTS
At 4 weeks, number of patients classified as 'cured' were 10/26 (38.4%) in Group A, 5/22 in group B (22.7%) and 3/21 (14.2%) in group C (p=0.002). Mycological cure rates at week 4 in group A, B, C were 21 (80.8%), 17 (81.0%), and 5 (26.3%) respectively (p=0.006). Plasma levels of itraconazole were comparable between three groups at week 2 and week 4. No statistically significant correlation was found between itraconazole levels and treatment response in any of the groups at 4 weeks. Incidence of adverse effects and recurrence rates were also similar among three groups.


CONCLUSION
Cure rates for chronic dermatophytosis were poor with all three itraconazole brands at 4 weeks of treatment. Higher cure rates were obtained with innovator drug as compared to multinational and local generic brands at 4 weeks. Plasma levels of three drugs were however similar, indicating that factors other than serum bioavailability are at play in determining response of chronic dermatophyte infections to oral itraconazole.