which is not easily absorbed by the lining of the stomach. The accompanying anion, for
example, a hydroxide or carbonate ion, helps neutralize the extra acid concentration in
the stomach. The cations from the antacid react with anions in a portion of the small
intestine called the jejunum, where the pH is basic, and the compound thus formed may
produce additional antacid effects in the small intestine.
2-21. SODIUM BICARBONATE
a. Action and Uses. Sodium bicarbonate, a systemic antacid, may be used to
combat systemic acidosis or render the urine alkaline. As a gastric antacid, it has
several disadvantages: its duration of action is short; its reaction with hydrochloric acid
produces carbon dioxide, which may cause stomach pains or exacerbate an ulcer, and
it will produce systemic alkalosis.
b. Usual Dose. The usual dose is 300 mg to 2 grams, 1 to 4 times daily.
c. Supply. Sodium bicarbonate is supplied as 600-mg tablets and as a powder.
It is also available as a tablet combined with charcoal and peppermint.
2-22. ALUMINUM HYDROXIDE GEL
a. Action and Uses. Aluminum hydroxide (Amphojel) is not an adsorbent, but it
does act chemically to neutralize gastric acidity. It is a nonsystemic antacid.
b. Administration. The drug is usually given orally 1 hour after meals or when
needed. The average single dose of tablets is 0.6 gm (2 tablets). The tablets are
chewed thoroughly before being swallowed. The usual dose of the liquid is 5 to 15 ml.
The bottle is shaken thoroughly before the drug is poured.
c. Untoward Effects. Constipation occurs in some people who take aluminum
compounds. However, there are no systemic effects, since the drug is not absorbed
from the gastrointestinal tract.
d. Cautions and Contraindications. The liquid preparation should be kept
e. Supply. The drug is supplied as a liquid suspension (320mg/5ml) in one-pint
bottles and as 300 mg and 600 mg flavored tablets.
2-23. ALUMINUM HYDROXIDE GEL AND MAGNESIUM HYDROXIDE
a. Action and Uses. Magnesium hydroxide is an antacid that acts both by
chemically reacting with stomach acid and by adsorbing it. This preparation is used to
treat hyperacidity and ulcers of the stomach. The drug is not adsorbed from the
intestinal tract. A preparation of magnesium hydroxide combined with aluminum