Adults and teenagers: 40 to 125 mg four times a day, after meals and at bedtime or the dose may be 150 mg three times a day, after meals. No more than 500 mg should be taken in twenty-four hours.
Friday, November 5, 2010
Dose
Chemical action:
Simethicone is an anti-foaming agent that decreases the surface tension of gas bubbles, causing them to combine into larger bubbles in the stomach that can be passed more easily by burping (release of gas from the digestive tract mainly form esophagus and stomach through the mouth) Simethicone does not reduce the quantity of gas in the digestive tract, it only increases the rate at which it exits the body, but does not prevent gas formation in the intestine. However, simethicone can relieve pain caused by gas in the intestines by decreasing foaming which then allows for passing of flatus. Simethicone is not absorbed by the body into the bloodstream, and is therefore considered relatively safe, with sources reporting the worst side effects as bloating, constipation, diarrhea, gas and heartburn. Simethicone solutions of differing concentration also have industrial applications for reducing foaming in certain chemical processes Simethicone is an anti-foaming agent that decreases the surface tension of gas bubbles, causing them to combine into larger bubbles in the stomach that can be passed more easily by burping. Simethicone does not reduce the quantity of gas in the digestive tract, it only increases the rate at which it exits the body, but does not prevent gas formation in the intestine[1]. However, simethicone can relieve pain caused by gas in the intestines by decreasing foaming which then allows for passing of flatus. Simethicone is not absorbed by the body into the bloodstream, and is therefore considered relatively safe, with sources reporting the worst side effects as bloating, constipation, diarrhea, gas and heartburn. Simethicone solutions of differing concentration also have industrial applications for reducing foaming in certain chemical processes
Drug names
Examples of antacids -
c) Aluminum hydroxide with magnesium hydroxide
d) Aluminum carbonate gel
g) Hydrotalcite [Mg6Al2(CO3)(OH)16 · 4(H2O)]
Problems with reduced stomach acidity
Reduced stomach acidity may result in an impaired ability to digest and absorb certain nutrients, such as iron and the B vitamins. Since the low pH of the stomach normally kills ingested bacteria, antacids increase the vulnerability to infection. It could also result in reduced bioavailability of some drugs. For example, the bioavailability of ketoconazole (antifungal) is reduced at high intragastric pH (low acid content).
Other adverse effects from antacids include:
1. 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.
2. 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.
3. Magnesium hydroxide: has laxative properties. Magnesium may accumulate in patients with renal failure leading to hypermagnesemia, with cardiovascular and neurological complications.
4. Sodium: increased intake of sodium may be deleterious for arterial hypertension, heart failure and many renal diseases.
Interactions
Altered pH or complex formation may alter the bioavailability of other drugs, such as tetracycline. Urinary excretion of certain drugs may also be affected.
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.
- It also causes renal failure, alkalosis, and hypercalemia, mostly in men with peptic ulcer disease.
Compounds containing calcium may also increase calcium output in the urine, which might be associated with kidney stones. Calcium salts may cause constipation.
Problems associated with antacid therapy:
1. The normal pH range of the stomach is 1-2, after the administration of antacid preparation it raises the pH range at 4-5 which greatly reduces pepsin’s proteolytic action. But if the ph of the stomach falls in this range, it turns to secrete additional HCl and finally acid rebound occurs.
Ø Antacid containing Al(OH)3 - Mg(OH)2 (30-60ml) and NaHCO3 (4-8gm) → failed to stimulate gastric secretion.
Ø Antacid containing Al(OH)3 - Mg(OH)2 (30-60ml) and CaCO3 (4-8gm) → induced gastric secretion.
2. If the antacid preparations are sufficiently water soluble then they are readily forms absorbable ions, this may turns systemic alkalosis.
3. Antacid therapy is not suitable for Na-restricted patients, where it causes hyper-natremia significantly.
4. It may produces local effect on GIT such antacid containing Ca and al-salts after being converted to soluble salts tend to be constipating. While antacid containing Mg-salts tend to produce laxative effects.
Antacids are taken by mouth to relieve –
Peptic ulcers may require H2-receptor antagonists or proton pump inhibitors. The utility of many combinations of antacids is not clear, although the combination of magnesium and aluminium salts may prevent alteration of bowel habits.
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