Magnesium Oxide–Induced Change in Gastric pH
Magnesium oxide (MgO) is a relatively poorly soluble antacid, so its neutralizing effect in gastric fluid is often modest and short-lived compared with more rapidly reacting antacids. (hero.epa.gov)
Expected Magnitude of Gastric pH Rise
In simulated gastric fluid titration data, a single tablet of magnesium oxide did not raise gastric pH above 3.0, whereas doubling the dose increased pH to higher (but excessive) levels (reported range 5.3 to 8.6). (hero.epa.gov)
Why the Effect Is Variable
MgO dissolution is pH dependent, with substantially lower solubility at higher pH conditions (which can reduce further acid-neutralizing capacity). [1]
Practical Interpretation for Clinical Use
MgO should be expected to reduce acidity without reliably achieving sustained normal gastric pH. (hero.epa.gov)