Therefore, magnesium salts are often combined with aluminum salts in antacids to balance their effects. Magnesium laxatives are indicated for acute bowel evacuation before diagnostic evaluation, for treatment of severe constipation from chronic opioid or laxative abuse, or for occasional use in healthy adults. Onset of laxative effect is observed within 30 minutes to 3 hours. Magnesium s mechanism of action is as an oral saline laxative and cathartic primarily by its osmotic effect in the colon. Magnesium increases gastric motility by stimulation of cholecystikinin, thus increasing fluid and electrolyte retention in the intestinal lumen.
Sulfate salts are the most potent.
Fruit juice or a carbonated drink can be mixed with it to hide the bitter taste. Bicitra is available as an oral solution. A 240-mL dose is equivalent to 4 g of magnesium hydroxide. With any of the laxative formulations, a large volume of water may be lost with passing the stool, so drinking a full glass of water after each dose is recommended. Magnesium salts are effective laxatives for acute bowel evacuation resulting in a dose-dependent increase in bowel movements and stool water.