The invention provides methods of treating and preventing asthma, laryngitis, symptomatic gastroesophageal reflux disease, pregnancy-induced gastroesophageal reflux disease, noncardiac chest pains, coughing, apnea, dyspepsia, inflammatory bowel disease, irritable bowel syndrome, gastritis, stress ulcers, bleeding peptic ulcers, acute gastrointestinal bleeding, infectious enteritis, collagenous colitis, lymphocytic colitis, chronic diarrhea in immunocompromised patients, esophageal ulcers in immunocompromised patients, idiopathic gastric acid hypersecretion, gastroparesis, gastrointestinal motility disorders, Zollinger-Ellison syndrome, short bowel syndrome, emesis, regurgitation, early satiety, chronic sore throat, abdominal pain, abdominal bloating, nausea, sour stomach, diarrhea, constipation, bacterial infections, refractory ulcers, gastrointestinal disorders induced by NSAIDs, Barrett's esophagus, gastrointestinal disorders caused by steroids, gastrointestinal disorders induced by cholinergic compounds, and fungal or viral-induced ulcers in the gastrointestinal tract by administering a therapeutically effective amount of at least one of the pyridine derivatives of the invention to a patient in need thereof. The invention also provides on demand relief of symptoms associated with gastroesophageal reflux disease (GERD), and provides relief from symptoms caused by the consumption of excessive amounts of food and/or alcohol by administering a therapeutically effective amount of at least one of the pyridine derivatives of the invention to a patient in need thereof. The invention also provides methods for treating parasitic infections, such as malaria, by administering a therapeutically effective amount of at least one of the pyridine derivatives of the invention to a patient in need thereof. In preferred embodiments, the pyridine derivative of the invention is rabeprazole, a pharmaceutically acceptable salt thereof, or a stereoisomer thereof.