Voriconazole is the first-line antifungal choice in the treatment of
invasive fungal infections (IFIs). Single nucleotide polymorphisms (SNPs) in drug-metabolizing and transporter genes may affect
voriconazole pharmacokinetics. This study aimed to determine the frequency of the
CYP2C19 rs4244285, rs4986893, rs72552267, and rs12248560,
CYP3A4 rs4646437, ABCB1 rs1045642, and
FMO3 rs2266782 alleles and determine the association between these genetic variants and
voriconazole concentrations in Thai patients with
invasive fungal infections. The study comprised 177 Thai patients with IFIs in whom seven SNPs in
CYP2C19,
CYP3A4, ABCB1, and
FMO3 were genotyped using TaqMan real-time polymerase chain reaction (RT-PCR) 5´ nuclease assays, and
voriconazole plasma concentrations were measured by high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Of the 177 patients included, 31 were <12 years and 146 were ≥12 years. The
CYP2C19 allele frequencies were 0.29 for *2, 0.060 for *3, 0.003 for *6, and 0.008 for *17. The allele frequency of
CYP3A4 (rs4646437) was 0.26, ABCB1 (rs1045642) was 0.36, and
FMO3 (rs2266782) was 0.16. The median
voriconazole dose/weight was significantly lower in patients aged ≥12 years when compared to the patients aged <12 years (P < .001). Patients aged <12 years with
CYP2C19*1/*2 exhibited significantly higher median
voriconazole plasma concentrations than those with the
CYP2C19*1/*1 (P = .038). However, there were no significant differences in median
voriconazole plasma concentrations among the
CYP2C19 genotypes in the patients aged ≥12 years. There was a lack of association observed among the
CYP3A4, ABCB1, and
FMO3 genotypes on the plasma
voriconazole concentrations in both groups of patients. Our findings indicate that
voriconazole plasma concentrations are affected by the
CYP2C19*2 allele in patients aged <12 years but not in patients aged ≥12 years.