Antacid combinations of magnesium and aluminium salts are superior to single component preparations because:
Mg (OH)2 has a quick onset whereas Al (OH)3 acts for a long time. Mg salts cause osmotic diarrhea whereas Al salts cause constipation.\ Combination of these two agents minimizes the impact on bowel movements.
They have rapid as well as sustained acid neutralizing action
They are less likely to affect gastric emptying
They are less likely to alter bowel movement
All of the above
Gastro-Intestinal Tract