Magnesium hydroxide:(Milk of magnesia)

 - Non-absorbable antacid has rapid onset of neutralization increasing pH up to 8-9.

Magnesium oxide and magnesium trisilicate:

  • neutralize acid slowly and have slow onset of action, and long duration. Magnesium trisilicate also coats base of ulcer by Sico2 (Physical action).

  • *They increase gut motility and produce diarrhea.