Assessment of Gastric pH Changes Induced by Ascorbic Acid Tablets

This study evaluates the use of ascorbic acid, vitamin C, to temporary reduce gastric pH in individuals with omeprazole induced hypochlorhydria. All participants will receive ascorbic acid tablets to measure the change in gastric pH.

Study Overview

• Status: Completed
• Conditions: Hypochlorhydria
• Intervention / Treatment: Drug: Omeprazole 20mg; Dietary supplement: Vitamin C

Detailed Description

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.

• Study Type: Interventional
• Enrollment (Actual): 11
• Phase: Phase 1

Contacts and Locations

Study Locations

• United States
  • Indiana
    • Indianapolis, Indiana, United States, 46202
      • Indiana University School of Medicine

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 30 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Experimental: omeprazole and ascorbic acid	Drug: Omeprazole 20mg; Omeprazole twice daily x 5 days; Dietary supplement: Vitamin C; Ascorbic acid x 1 on day 5

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in gastric pH and duration of gastric pH \status	Gastric pH measurements will be continuously monitored throughout the study using a catheter-based pH monitoring system. Gastric pH versus time data will be collected for five hours.	From time of inpatient appointment to thirteen months after that time point.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Intestinal microbiome profile, intestinal metabolomic profile	To explore the correlation between physiologic responses in gastric pH with features of the intestinal microbiome and microbial metabolites (e.g. metabolome).	From time of initial stool drop-off to thirteen months after that time point.

Collaborators and Investigators

• Sponsor: Indiana University
• Collaborators: Hala Fadda; Butler University

Study record dates

Study Major Dates

• Study Start (Actual): October 1, 2021
• Primary Completion (Actual): June 7, 2023
• Study Completion (Actual): June 7, 2023

Study Registration Dates

• First Submitted: December 12, 2019
• First Submitted That Met QC Criteria: December 12, 2019
• First Posted (Actual): December 16, 2019

Study Record Updates

• Last Update Posted (Estimated): September 22, 2025
• Last Update Submitted That Met QC Criteria: September 16, 2025
• Last Verified: September 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Metabolic Diseases; Digestive System Diseases; Gastrointestinal Diseases; Stomach Diseases; Acid-Base Imbalance; Nutritional and Metabolic Diseases; Achlorhydria; 2-Pyridinylmethylsulfinylbenzimidazoles; Sulfoxides; Sulfur Compounds; Organic Chemicals; Pyridines; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds; Benzimidazoles; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Carbohydrates; Sugar Acids; Acids, Acyclic; Carboxylic Acids; Hydroxy Acids; Ascorbic Acid; Omeprazole
• Other Study ID Numbers: 2006413011

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: Yes