The azole antifungal voriconazole is known to achieve variable therapeutic concentrations, both between and within patients. A recent study conducted by researchers in Japan investigated the variability of the drug under the influence of concurrent corticosteroid treatment.
The study involved 85 samples from 38 immunocompromised patients, reviewed retrospectively. Patients were administered with voriconazole and/or corticosteroid medication orally or intravenously. Corticosteroid treatment was classed as ‘concurrent’ if administered within 3 days of voriconazole administration.
Patients received an average of 59.2 mg of corticosteroid daily. Voriconazole concentrations were inversely correlated with corticosteroid dose (r-.26) and voriconazole concentration was significantly lower in corticosteroid users compared with those who did not receive corticosteroid medication (p=.013).
The authors of the study speculate that voriconazole might be metabolized by an enzyme induced by corticosteroid treatment. Thus clinicians might be best advised to carefully consider voriconazole metabolism prior to concurrent treatment with corticosteroids.