Impact of Chronological Age, Proton Pump Inhibitors in Older Adults, and Diabetes in Older Adults on Physicochemical Characteristics of Antral Contents During Fasting: An Exploratory Study

We explored the impact of chronological age, proton pump inhibitors (PPIs) in older adults, and Type II diabetes in older adults on pH, buffer capacity, lipase activity, pepsin activity, individual bile acids, and osmolality in antral contents during fasting to evaluate whether drug product disposition is likely to differ from healthy adults. Antral contents were aspirated from 20 adults (Reference Group, RG), 14 older adults (Test Group 1, TG1), 7 older adults on PPIs (Test Group 2, TG2), and 6 diabetic older adults (Test Group 3, TG3). All subjects were free of additional conditions likely to confound the luminal characteristics of interest and were living with up to mild frailty. Median TG2 pH (7.84) was significantly higher than the median RG pH (1.75). Median buffer capacity across all groups was 10.38-19.85 mmolNaOH/L/ΔpH. Mean lipase activity was 96.72-124.47 Utrib/mL. Mean TG2 pepsin activity (32,500 USPunits/mL) was significantly lower than mean RG pepsin activity (176,669 USPunits/mL). Based on medians, glycochenodeoxycholic was the most abundant bile acid in TG2; glycocholic was the most abundant bile acid in all other groups. Median total bile acid content across all groups was 98.1-896.4 μM. Median osmolality was 257-328 mOsmol/kg. Chronological ageing is unlikely to affect drug disposition during fasting via changes in the physicochemical characteristics of antral contents. Caution should be exercised when fasted older adults are on PPIs and the drug or the drug product is sensitive to gastric pH and/or pepsin activity. Power-based sample-size estimations might allow for clarifying the impact of Type II diabetes on fasting gastric pH.