Prevalence of exposure to pharmacogenetic drugs by the Saudis treated at the health care centers of the Ministry of National Guard.

Background: The drugs impacted by genetic variants are known as pharmacogenetic (PGx) drugs. Patients' responses to these drugs may vary according to the variability in patients' genetic makeup. Hence, exploring the pharmacogenes that affect drug treatment is vital to ensure optimal therapy and patients' safety. This study aimed to describe the usage rate of PGx drugs and the frequency of relevant variants in the Saudi population. Methodology: Prescription patterns over seven years (2015-2021) for Saudi patients on PGx drugs treated at the Ministry of National Guard-Health Affairs (MNG-HA) were investigated. Only registered drugs in the MNG-HA formulary (n = 78) were included. The patients were subgrouped into four age groups: ≤24, 25-44, 45-64, and ≥65 years. Further subgrouping was made according to gender and drugs' therapeutic categories following anatomical therapeutic chemical (ATC) classification.Furthermore, an online searching was carried out to identify the pharmacogenes reported in the literature among healthy Saudis. The search included 45 genes that may affect drug outcomes based on evidence rated by either CPIC (A-B levels) or PharmGKB (1-2 levels). Results: The screened patients were 1,483,905. Patients on PGx drugs accounted for 46.7% (n = 693,077 patients). The analgesic group was the most prescribed drug category (47%), which included ibuprofen (20.5%), celecoxib (6.3%), tramadol (5.8%), and others. Cardiovascular agents were the second-most utilized drug class (24.4%). Omeprazole was the second most commonly used medication (11.1%) but ranked third as a class (gastroenterology). Females used PGx drugs more frequently than males (53.5% versus 46.5%) and a higher usage rate by patients aged 45-64 years (31.3%) was noted. The cytochrome P450 genes (CYP2C9, CYP2C19, and CYP2D6) were estimated to impact responses of 54.3% (n = 1,156,113) of the used drugs (27.2% are possibly affected by CYP2C9, 12.8% by CYP2C19, and 14.3% by CYP2D6). Thirty-five pharmacogenes that characterize Saudi population and their variants' allele frequencies were identified from previous reports. This study presents the largest reported number of genes that may affect drug therapies among Saudis. Conclusion: This study confirmed that a high percentage of Saudi patients use PGx drugs and various genotypes of certain pharmacogenes are inherited by the Saudi population.