# Evidence: gastric pH variability

Parent: — · class: transport and absorption · names merged here: gastric pH variability

3 papers measured or used it, 0 only mentioned it (of 207 kept papers). Papers in year order; each section heading ends with the paper's category / subcategory. Generated by tools/build_evidence.py from registry/concepts.csv and the cards; do not edit.

## 2023 Nguyen — Enteric coating of tablets containing an amorphous solid dispersion of an enteric polymer and a weakly basic drug: A strategy to enhance in vitro release · Dissolution / B. Supersaturation from ASD dissolution

[2023-nguyen-enteric-coating-delamanid-hpmcp-asd-release](../../../cards/2023-nguyen-enteric-coating-delamanid-hpmcp-asd-release/paper.html) · Dissolution / B. Supersaturation from ASD dissolution · used · as: gastric pH variability

| id | kind | content | locator |
|---|---|---|---|
| C12 | claim, prior hypothesis, authors: "It was hypothesized"; "was expected" | An enteric coating would protect the ASD against unfavourable pH conditions where the polymer cannot inhibit crystallization, keep the dissolution benefit at higher pH where the polymer is soluble and a better inhibitor, and so reduce release variability across gastric pH reflecting prandial states [rests on: argument only] | p.2 |
| C19 | claim, assumption, authors: asserted ("it is important") | The 30-60 min gastric stage reflects fasted gastric emptying (15-60 min); food prolongs gastric residence (2-5 h) and makes gastric pH variable, so the integrity of an enteric coating must be evaluated against food, pH and prolonged residence [rests on: R22; cited: refs 1, 8, 11, 18, 28, 40, 45] | p.4 |
| C42 | claim, generalisation, authors: "may be of importance" | Because in vitro tests rarely cover the range of gastric pH, these observations may matter for in vivo behaviour, where gastric pH is highly variable in fasted and fed states [rests on: R2; cited: refs 8, 22, 34] | p.9 |
| R22 | record, cited | gastric physiology values used for test design — refs 1, 3, 8, 11, 18, 25, 28, 29, 40 — gastric emptying time 15-60 min fasted and 2-5 h fed; gastric pH 30 min post-prandial 6-6.5 | p.4 |

## 2023 Nguyen — Impact of Gastric pH Variations on the Release of Amorphous Solid Dispersion Formulations Containing a Weakly Basic Drug and Enteric Polymers · Dissolution / B. Supersaturation from ASD dissolution

[2023-nguyen-gastric-ph-variations-delamanid-enteric-polymer-asd](../../../cards/2023-nguyen-gastric-ph-variations-delamanid-enteric-polymer-asd/paper.html) · Dissolution / B. Supersaturation from ASD dissolution · used · as: gastric pH variability

| id | kind | content | locator |
|---|---|---|---|
| R24 | record, cited | gastric physiology used to set the gastric pH values — refs 40-45, 58, 60, 61 — peak gastric pH ∼6.0-7.0 after a meal, back to fasting levels after 1-4 h; pH 6.4, 5.0 and 3.0 represent early (first 20-75 min), middle (until 160 min) and late (after 160 min) times after a meal; gastric residence 15-60 min fasted and 2-5 h fed | p.1682, p.1688 |
| C5 | claim, recommendation, authors: abstract: "These findings suggest"; discussion: "highlight the need to consider" | Gastric pH variations should be evaluated, and considered, for ASDs containing weakly basic drugs and enteric polymers; in vitro testing is usually standardized and rarely varies gastric pH [rests on: R7, R11] | p.1681, p.1692 |
| C57 | claim, generalisation, authors: "may be important"; "postulated impact on absorption" | For a weakly basic drug with a high crystallization tendency, gastric pH variations (inter- and intra-subject variability, age, prandial state, acid-reducing agents) may be important in vivo for how much drug is absorbed [rests on: R7, R11] | p.1692 |

## 2025 Kaur — Impact of drug-polymer complexation and media properties on the release performance of amorphous solid dispersions containing a weakly basic drug and hydroxypropyl methylcellulose acetate succinate · Dissolution / A. Release mechanism and LoC

[2025-kaur-bdq-hpmcas-complexation-media-asd-release](../../../cards/2025-kaur-bdq-hpmcas-complexation-media-asd-release/paper.html) · Dissolution / A. Release mechanism and LoC · used · as: gastric pH variability

| id | kind | content | locator |
|---|---|---|---|
| P11 | method | two-stage pH-shift powder dissolution | p.4, p.6 |
| R12 | record, measured | BDQ concentration in two-stage pH-shift release (µg/mL; maximum theoretical 100 µg/mL; mean of n = 3) — 5/95 ASDs (P11) — sub-table below; text: first stage below 10% released, highest at pH 1.6 | Fig. 4A, 4C, p.6 |