Nonsystemic antacid

Magnesium oxide is an effective nonsystemic antacid, ie, it is converted to the hydroxide. It does not neutralize gastric acid excessively nor does it hberate carbon dioxide. The light form is preferable to the heavy for adininistration in Hquids because it is suspended more readily. One gram of magnesium oxide neutralizes 87 mL of 0.1 NUCl in 10 min, and 305 mL in 2 h. 

Magnesium trisihcate is a nonsystemic antacid and an adsorbent. It has a slow onset of activity and is a relatively weak antacid. It may cause diarrhea in large doses owing to soluble magnesium salts. One gram of magnesium trisihcate neutralizes 10 mL of 0.1 NUCl in 10 min, and 15 mL in 2 h. 

Mechanism of Action. The drug is usually absorbed by the oral route upto 90-100%. However, its absorption is predominantly diminished to a small extent milk and food intake and appreciably by the presence of iron preparations and nonsystemic antacids . It is protein-bound in plasma between a range of 70-75%. The volume of distribution v/ stands at 0.14 - 0.7 mL. The plasma half-life ranges between 11-17 hours. It gets excreted unchanged in urine upto 10% however, its biological half-life is usually prolonged chiefly in the incidence of renal failure. 

Nonsystemic antacids are composed of alkaline salts such as aluminum (aluminum hydroxide, aluminum carbonate) and magnesium (magnesium hydroxide, magnesium carbonate, magnesium trisilicate, and magnesium phosphate). A small degree of systemic absorption occurs with these drugs—mainly with aluminum. 

Magnesium trisilicate occurs in nature as the minerals meerschaum, parasepiolite, and sepiolite. It has been used as a nonsystemic antacid and as an adsorbent. It is claimed to exert a protective action in the stomach by... 

Calcium carbonate is classified as a nonsystemic antacid in that it does not tend to cause a systemic alkalosis, a condition in which the alkalinity of body fluids and tissues becomes abnormally high. However, long term therapy with large doses taken with milk or other somces of phosphate will... 

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