This interrupted case study is designed to teach students about chirality and the pH scale in the context of medicinal chemistry. Students read about a college student who wakes in the middle of the night with chest pains. Upon examination in the emergency room, she is determined to be suffering from gastroesophageal reflux disorder (GERD). Students learn about the drug esomeprazole (Nexium) and its stereochemical relationship to its precursor, omeprazole (Prilosec). They also learn about the pH scale as they investigate the mechanism of action of these drugs. Students are asked to read about the development and activity of esomeprazole and write a brief essay arguing whether esomeprazole is an improvement over omeprazole. This case may be used in a survey course of general, organic, and biochemistry or can be modified for use in a sophomore-level organic chemistry course, an introductory pharmacology course, an upper-level medicinal chemistry course, or a general biology course.