Interindividual differences in response to medication therapy is, alongside environmental factors, greatly dependent on the human genome. Based on that intellection and the discoveries of new molecular diagnostic methods, the rapid development of a new scientific branch occurred called pharmacogenomics. One of the most significant pharmacogenes is CYP2C19 which affects the metabolism of clopidogrel and the first generation of proton pump inhibitors - pantoprazole, lansoprazole and omeprazole. The role of CYP2C19 in clopidogrel metabolism is the transformation of the prodrug into its active form. Because of that, the amount of active drug is higher with increased enzyme activity. On the other hand, decreased enzyme activity increases the risk of thromboembolic incidents because of lower active drug concentrations. The role of CYP2C19 in the metabolism of proton pump inhibitors is the creation of degradation products which are ultimately eliminated from the body. That is why in individuals with lower enzyme activity, accumulation, and toxicity of the drug occur. Also, in individuals with increased enzyme activity, because of the rapid elimination and low plasma concentrations of the drug, the response to medication therapy is depleted. Clopidogrel optimization therapy guidelines have a high level of evidence and recommend genotyping of the patient, while the proton pump inhibitors guidelines have a lower level of evidence, and further research is needed. With a high level of evidence, economic benefits, and better patient outcomes, application of discoveries in pharmacogenomics into clinical practice is taking slow. Some of the main obstacles are the obsolescence of the information system, lack of information on the medical staff, duration of the molecular diagnostic methods, and different legislatures in each country. Despite that, there are good examples of good clinical practice with elaborated solutions by whose application we can turn unsustainable healthcare systems of today into prosperous healthcare systems of the future.