Frequency and impact of DHODH, ABCG2 and CYP2C19 SNPs on the therapeutic efficacy, tolerability and toxicity of leflunomide.

Leflunomide is one of the commonly used drugs in treatment of rheumatoid arthritis (RA), which on administration is converted into its active metabolite teriflunomide. Our aim is to evaluate the frequencies of dihydrooroate dehydrogenase (DHODH) (rs3213422), ABCG2 (rs2231142) and CYP2C19 (rs4244285) allele distribution among patients receiving leflunomide for RA and their possible impact on leflunomide performance in disease control. Patients (>18 years) who fulfilled the 2010 ACR classification criteria for RA receiving leflunomide (20 mg/day) were included in the study.