Fluconazole plasma concentration measurement by liquid chromatography for drug monitoring of burn patients

Abstract

Fluconazole (2-(2,4-difluorophenyl)-1,3-bis(1H-1,2,4-triazol-1-yl)-2-propanol) is a triazole antifungal agent that has been available since 1990. Fluconazole is a broad-spectrum triazole antifungal agent that has emerged as a suitable alternative to amphotericin B in the treatment of a wide variety of superficial and systemic fungal infections.1 Triazole drugs act by inhibiting the enzyme 14-α-demethylase, which belongs to the microsomal CYP system; triazoles also act by blocking the biosynthesis of ergosterol, resulting in the accumulation of 14-α-methyl sterols and producing a fungistatic action. In general, fluconazole is well tolerated, with side effects including nausea, headache, skin rash, vomiting, abdominal pain, and diarrhea occurring during long-term therapy.2 Excellent bioavailability has been reported after oral dosing, and a linear pharmacokinetics has been demonstrated at a dose of 200–800 mg daily. The elimination half-life of fluconazole ranges from 27 to 37 hours, the apparent volume of distribution ranges from 0.5 to 0.7 L/kg, and approximately 80% of unchanged drug is excreted in the urine.3–6 Fluconazole is now used prophylactically in the management of various immune-compromised patient subsets1. High morbidity and mortality in patients with severe thermal injury were associated with fungal sepsis; thus, a study of the efficacy of this drug to prevent fungal sepsis in burn patients is necessary. It is well-known that patients with thermal injuries show many changes in the pharmacokinetics of several drugs, but data on the clinical efficacy of fluconazole related to its kinetics are very limited.7,8 Since changes in the pharmacokinetics of fluconazole are still unknown, it is imperative to investigate burn patients’ drug levels with a controlled clinical protocol. Analytical methods using microbiological, spectrophotometric, and chromatographic techniques have all been shown to determine fluconazole in biological samples. High-performance liquid chromatography (HPLC) is preferred due to its selectivity and the specificity of the assay. Methods for the determination of fluconazole in biological samples by HPLC-UV have been described previously.9–16 The objective of the present study was to develop a simple analytical method to determine fluconazole for plasma drug monitoring in patients with extensive thermal injury. An additional focus is its application to future pharmacokinetic studies. The method was validated as per FDA guidelines.17