doi.org/10.36721/PJPS.2020.33.4.SUP.1771-1777.1 Pak. J. Pharm. Sci., Vol.33, No.4(Suppl), July 2020, pp.1771-1777 1771 Pharmacogenetics of sulfonylurea: Presence of CYP2C9*2, CYP2C9*3 and a novel allele, CYP2C9*61, in Type 2 diabetes patients under sulfonylurea therapy Sumaira Deen Muhammad 1,3 , Hazar Khan 1,3 , Mushtaq Hussain 1* , Tehseen Fatima Zeb 1 , Darshan Kumar 2 , Rahimullah Rahi 3 , Mahayrookh Asif 1 and Akhter Ali Balooch 2 1 Bioinformatics and Molecular Medicine Research Group, Dow Research Institute of Biotechnology and Biomedical Sciences, Dow College of Biotechnology, Dow University of Health Sciences, Karachi, Pakistan 2 National Institute of Diabetes and Endocrinology, Dow University of Health Sciences, Karachi, Pakistan 3 Bolan University of Medical and Health Sciences, Quetta, Pakistan Abstract: CYP2C9 is an important member of the cytochrome P450 gene family involved in the metabolism of 15% of the drugs including an oral antidiabetic agent sulfonylurea. This study aims to investigate the frequency of CYP2C9*2 and CYP2C9*3 alleles of the gene in the sulfonylurea treated diabetic subjects in Pakistan. Briefly, total 105 patients were included in the study and segregated as control (24) and test (81) based on the clinical manifestations after taking sulfonylurea. Genomic DNA was extracted from blood of the subjects and amplified using CYP2C9 specific primers for exon 3 and exon 7 and then subjected to DNA sequencing. Alignment of the sequences with the reference sequence shows presence of CYP2C9*3/*3, CYP2C9*1/*3 and CYP2C9*1/*2 genotypes in the test cases but only the latter two were found in the control cases. In addition a novel allele, CYP2C9*61 in the heterozygous state, was also identified frequently in the test cases. Molecular structure comparison also showed variations in the structural features of protein encoded by the allelic variants. To the best of our knowledge, the present data is the first report for CYP2C9 allelic variations in the indigenous diabetic subjects and also report the existence of novel allelic variant of CYP2C9, CYP2C9*61. Keywords: Diabetes mellitus, CYP2C9, pharmacogenetics, sulfonylurea. INTRODUCTION Diabetes mellitus (DM) is a polygenic and multifactorial disease characterized by the persistent hyperglycemia. According to international federation of diabetes (2019), approximately 463 million adults (20-79 years) were living with diabetes. Type 2 Diabetes is “non-insulin- dependent diabetes” previously known as “adult onset diabetes” and it accounts for 90–95% of all diabetes cases. Around, 79% of adults with diabetes were living in low- and middle-income countries and the prevalence of T2DM in Pakistan is 13.7%, a lot higher than had been anticipated (Adnan and Aasim, 2020). Use of modern medicine and life style modification in regard to dietary habits and physical exercise play a fundamental role in the management of T2DM. However, once individual become diabetic, with nearly no exception patient requires pharmacological management. Pharmacological interventions of diabetes are broadly classified as injectable and oral intervention. Amongst the several oral antidiabetic agents, sulfonylurea holds profound importance. Sulfonylurea (SUs) is an oldest oral anti-diabetic drug class used as second line or as add on therapy in T2DM patients (Qian et al., 2018). Drugs included in sulfonylurea class are divided in to four generations. First generation include acetohexamide, chlorpropamide, tolbutamide and tolazamide. Glyburide, glipizide gliclazide, gliclazide MR are the members of second generation whereas glimipride is an example of third generation SUs. Compared to first and second generation, SUs drugs of third generation have improved safety and tolerability profile (Cordiner and Pearson, 2018). JB253, which is under clinical trials, potentially represent fourth generation sulfonylurea (Broichhagen et al., 2014). First-generation SUs are still in use but comprises only 3% of all oral anti hyperglycemic drug prescriptions. However, second- and third-generation SUs are more widely used, accounting for 20% to 30% of all anti diabetic drug consumption (Rados et al., 2014). Mechanistically, after oral absorption, SUs bind to the receptor SUR subunit present on plasma membrane of β- cell. This binding blocks ATP sensitive potassium channels of β-cells thus inhibiting K+ efflux and cause depolarization of membrane. This in turn stimulates influx of Ca2+ ions resulting in the exocytosis of preform insulin (Sola et al., 2015; Lv et al., 2020). SUs are metabolized in the liver by cytochrome P4502C9 (CYP2C9) enzyme and mutations in the enzymes may result in the impaired metabolism and unwanted retention and reduced clearance of the drug. This consequently leads to the development of adverse side effects of SUs which is mainly hypoglycemia (Loganadan et al., 2016). *Corresponding author: e-mail: mushtaq.hussain@duhs.edu.pk