Chronological age, proton pump inhibitors in older adults, and diabetes in older adults on physicochemical characteristics of contents of the descending duodenum during fasting: An exploratory study.

Median pH in the Reference Group of healthy young adults was 7.83 in the descending duodenum during fasting, consistent with previous observations.

• Reference Group consisted of 17 adults aged 27-43 years free of conditions that confound luminal physicochemical characteristics
• Median [range] pH values were 7.83 [2.36-8.58]
• In all Test Groups (older adults, older adults on PPIs, diabetic older adults, diabetic older adults on PPIs), the median pH was slightly higher than 8
• The wide range in the Reference Group (2.36-8.58) reflects variable interdigestive motility patterns during fasting

Buffer capacity in the Reference Group had a median of 13.76 mmol HCl/L/ΔpH, and values across Test Groups ranged from 6.88 to 17.01 mmol HCl/L/ΔpH.

• Reference Group median [range] buffer capacity was 13.76 [3.36-67.80] mmol HCl/L/ΔpH
• Test Group median buffer capacity values ranged from 6.88 to 17.01 mmol HCl/L/ΔpH
• Test Groups included 34 older adults (65-91 years), 20 older adults on PPIs (68-84 years), 10 diabetic older adults (68-79 years), and 7 diabetic older adults on PPIs (67-82 years)
• Differences in buffer capacity across groups were considered too small to impact oral drug absorption

The predominant bile acids in all groups were glycocholic acid and glycochenodeoxycholic acid, consistent with previous observations in healthy adults.

• Glycocholic acid and glycochenodeoxycholic acid were the predominant bile acids across all five groups (Reference and four Test Groups)
• This pattern is described as 'in line with previous observations in healthy adults'
• Median total bile acid content in the Reference Group was 1.98 mM
• Median total bile acid content in Test Groups was slightly higher, ranging from 2.26 to 3.48 mM

Total bile acid content in the Reference Group was slightly lower than in the Test Groups (1.98 mM vs. 2.26-3.48 mM).

• Reference Group median total bile acid content was 1.98 mM, described as 'in line with previous estimates in young adults'
• Test Group medians ranged from 2.26 to 3.48 mM, all slightly higher than the Reference Group
• The difference was not considered large enough to impact oral drug absorption
• Samples were aspirated from the second part of the duodenum after overnight fasting from food and water

PPIs decreased mean osmolality in older adults compared to older adults not on PPIs (274 vs. 333 mOsmol/kg).

• Mean osmolality in older adults on PPIs (Test Group 2, n=20, aged 68-84 years) was 274 mOsmol/kg
• Mean osmolality in older adults not on PPIs (Test Group 1, n=34, aged 65-91 years) was 333 mOsmol/kg
• This PPI effect on osmolality is described as 'in line with previous observations in adults'
• Chronological ageing alone did not appear to affect osmolality

Chronological ageing alone does not appear to affect osmolality of fasted duodenal contents.

• Osmolality was compared between the Reference Group (adults 27-43 years, n=17) and Test Group 1 (older adults 65-91 years, n=34)
• The paper states 'osmolality does not seem to be affected by chronological ageing'
• The reduction in osmolality was attributed specifically to PPI use, not to age

All test group participants were non-frail and free of additional conditions that could confound luminal physicochemical characteristics, establishing a controlled study population.

• Test Group 1: 34 older adults aged 65-91 years
• Test Group 2: 20 older adults on PPIs aged 68-84 years
• Test Group 3: 10 diabetic older adults aged 68-79 years
• Test Group 4: 7 diabetic older adults on PPIs aged 67-82 years
• All participants underwent overnight fasting from food and water before duodenal content aspiration

The combined effects of chronological age, PPI use in older adults, and Type II diabetes in older adults on fasted duodenal pH, buffer capacity, and bile acid concentrations are too small to impact oral drug absorption.

• The study evaluated pH, buffer capacity, individual bile acid concentrations, and osmolality
• The purpose was to evaluate whether drug disposition in the upper small intestine of these populations is likely to differ from healthy adults
• Despite small numerical differences observed across groups, the authors concluded these differences would not meaningfully affect oral drug absorption
• This was described as an exploratory study