In this study, the relationships between 15 N-NMR and 13 C-NMR chemical shifts of omeprazole, lansoprazole, ilaprazole, pantoprazole, and rabeprazole and their physicochemical and pharmacokinetic properties, namely, pK a , half-life, t max , logP, and protein binding were investigated. This study also presents the first report of 15 N-NMR spectroscopic studies of lansoprazole, pantoprazole, and ilaprazole. It was found that 15 N-NMR chemical shifts of the doubly bonded benzimidazole nitrogen of

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... proton pump inhibitors showed correlation with pK a 2, protein binding and logP, while 15 N-NMR chemical shifts of the pyridine nitrogen correlate with protein binding and t max . Sum of 15 N-NMR chemical shifts and sum of 13 C-NMR chemical shifts, both, exhibit correlation with half-life, logP, and t max . The sum of 13 C chemical shifts of the pyridine moiety exhibits correlation with pK a 1, while the sum of 13 C chemical shifts of the benzimidazole moiety exhibits correlation with half-life. NMR chemical shifts may, hence, be useful as molecular descriptors in the development of Quantitative Structure/Spectral Data Property Relationship models.