Antacid

Antacid
An antacid is any substance, generally a base or basic salt, which neutralizes stomach acidity.
Mechanism of action
Antacids perform a neutralization reaction, i.e. the buffer gastric acid, raising the pH to reduce acidity in the stomach. When gastric hydrochloric acid reaches the nerves in the gastrointestinal mucosa, they signal pain to the central nervous system. This happens when these nerves are exposed, as in peptic ulcers. The gastric acid may also reach ulcers in the esophagus or the duodenum.
Side effects
Excess calcium from supplements, fortified food and high-calcium diets, can cause the milk-alkali syndrome, which has serious toxicity and can be fatal. In 1915, Bertram Sippy introduced the "Sippy regimen" of hourly ingestion of milk and cream, the gradual addition of eggs and cooked cereal, for 10 days, combined with alkaline powders, which provided symptomatic relief for peptic ulcer disease. Over the next several decades, the Sippy regimen resulted in renal failure, alkalosis, and hypercalcaemia[clarification needed], mostly in men with peptic ulcer disease. These adverse effects were reversed when the regimen stopped, but it was fatal in some patients with protracted vomiting. Milk alkali syndrome declined in men after effective treatments were developed for peptic ulcer disease. But during the past 15 years, it has been reported in women taking calcium supplements above the recommended range of 1200 to 1500 mg daily, for prevention and treatment of osteoporosis, and is exacerbated by dehydration. Calcium has been added to over-the-counter products, which contributes to inadvertent excessive intake. The New England Journal of Medicine reported a typical case of a woman who arrived in the emergency department vomiting and in altered mental status, writhing in pain. She had consumed large quantities of chewable antacid tablets containing calcium carbonate. She gradually recovered.[1]
Compounds containing calcium may also increase calcium output in the urine, which might be associated with kidney stones.[2] Calcium salts may cause constipation.
Other adverse effects from antacids include:
• Carbonate: regular high doses may cause alkalosis, which in turn may result in altered excretion of other drugs, and kidney stones. A chemical reaction between the carbonate and hydrochloric acid may produce carbon dioxide gas. This causes gastric distension which may not be well tolerated. Carbon dioxide formation can also lead to headaches and decreased muscle flexibility.
• Aluminum hydroxide: may lead to the formation of insoluble aluminium-phosphate-complexes, with a risk for hypophosphatemia and osteomalacia. Although aluminium has a low gastrointestinal absorption, accumulation may occur in the presence of renal insufficiency. Aluminium-containing drugs may cause constipation.
• Magnesium hydroxide: has laxative properties. Magnesium may accumulate in patients with renal failure leading to hypermagnesemia, with cardiovascular and neurological complications. See Milk of magnesia.
• Sodium: increased intake of sodium may be deleterious for arterial hypertension, heart failure and many renal diseases.
Side effects from antacids vary depending on individual and other medications they may be taking at the time. Those who experience side effects most commonly suffer from changes in bowel functions, such as diarrhea, constipation, or flatulence.
Although reactions to any drug may vary from person to person, generally those medications that contain aluminum or calcium are the likeliest to cause constipation, those that contain magnesium are the likeliest to cause diarrhea. Some products combine these ingredients, which essentially cancels them out, to forestall unpleasant side effects.
Some famous antacid brands
• Alka-Seltzer – NaHCO3 and/or KHCO3
• Andrews Antacid – CaCO3 MgCO3
• Brioschi - CHNaO3 (only FDA approved All-Natural)
• Equate – Al(OH)3 and Mg(OH)2
• Gaviscon – Al(OH)3
• Maalox (liquid) – Al(OH)3 and Mg(OH)2
• Maalox (tablet) – CaCO3
• Milk of Magnesia – Mg(OH)2
• Pepto-Bismol – C7H5BiO4
• Pepto-Bismol Children’s – CaCO3
• Rolaids – CaCO3 and Mg(OH)2
• Tums – CaCO3
• Mylanta - contains Al(OH)3
• Eno
• Gelusil (tablet,syrup)
• Alusil MPS (tablet)