Assessment of Gastric pH Changes Induced by Ascorbic Acid Tablets

Elevation of gastric pH in patients with hypochlorhydria can reduce the solubility of weakly basic drugs. This may lead to poor and unpredictable systemic exposure for poorly soluble drugs. For example, extent of absorption of the kinase inhibitors, dasatinib (Sprycel) and erlotinib (Tarceva), is reduced by up to 61% and 46% respectively in patients on acid-reducing agents (ARAs). This pilot study is to evaluate the use of ascorbic acid, vitamin C, to temporary reduce gastric pH in individuals with omeprazole induced hypochlorhdyria. Using pH/impedance testing, we are seeking to determine the magnitude and duration of pH change upon administration of 1000 mg of ascorbic acid in healthy subjects with proton-pump inhibitor induced hypochlorhydria. The results from this study will be used to evaluate the use of ascorbic acid as a drug-drug interaction mitigation strategy.

Inclusion criteria

• Healthy, young males age 18-30 years with no prior history of gastrointestinal disease or symptoms.

Exclusion criteria

• Hypochlorhydria (baseline use antacids, antisecretory medications, or surface agents including proton-pump inhibitors, H2 blockers, or sucralfate).
• Current or previous history of gastrointestinal disease including gastroesophageal reflux disease, Barrett's esophagus, peptic ulcer disease, dyspepsia, gastroparesis, bacterial overgrowth, microscopic colitis, gastric intestinal metaplasia or metaplastic atrophic gastritis, gastric neuroendocrine tumors, helicobacter pylori infection, inflammatory bowel disease (Crohn's disease or ulcerative colitis), celiac disease, visceral cancer, chronic infectious disease, immunodeficiency, uncontrolled thyroid disease, history of liver disease).
• History of gastric bypass or other abdominal surgeries excluding cholecystectomy or appendectomy > 6 months prior to study initiation.
• Radiation therapy to the abdomen.
• Pregnant females.
• Ingestion of any prescription, over-the-counter, or herbal medications which may affect study interpretation.
• Currently a smoker
• Antibiotic use within the last 3 months