CYP2C19 and gastroesophageal reflux disease: Despite the extensive literature on the impact of CYP2C19 genotypes on omeprazole pharmacokinetics, studies investigating the clinical efficacy of omeprazole with CYP2C19 rapid metabolizers (RMs) (*1/*17) and UMs (*17/*17) remain limited and were mostly carried out in non-GERD samples (Arévalo Galvis et al., 2019; Chwiesko et al., 2016; Molina-Infante et al., 2015).