Antacids

Acid Controlling Agents
Antacids
I. Mechanism of Action
A. promote gastric mucosal defense mechanisms
1. secretion of:
a. mucus: protective barrier against HCl
b. bicarbonate: helps buffer acidic properties of HCL
c. prostaglandins: prevent activation of proton pump
B. antacids DO NOT prevent the overproduction of acid
C. antacids DO neutralize the acid once it is in the stomach (only neutralize, don’t prevent)
D. Work primarily by neutralizing gastric acidity.
E. Reduction of pain associated with acid related disorders
1. raising gastric pH from 1.3 to 1.6 neutralizes 50% of gastric acid
2. raising gastric pH 1 point (1.3 to 2.3) neutralizes 90% of gastric acid
3. reducing acidity, reduces pain
II. Indications
A. indicated for the acute relief of symptoms associated with peptic ulcer, gastritis, gastric hyperacidity, and heartburn.
III. Contraindications
A. known allergy
B. severe renal failure or electrolyte disturbances
IV. Drug profiles
A. OTC formulations available as:
1. capsules and tablets
2. powders
3. chewable tablets
4. suspensions
5. effervescent granules and tablets
V. antacids can be used alone or in combination with:
A. aluminum salts
1. forms: carbonate, hydroxide
2. have constipating effects
3. often used with magnesium to counteract constipation
4. examples:
a. aluminum carbonate (Basaljel)
b. Hydroxide salt (Alterna GEL)
c. Combination products: (alum & magn) Gaviscon, Maalox, Mylanta, DiGel
B. magnesium salts
1. forms: carbonate, hydroxide, oxide, trisilicate
2. commonly cause diarrhea, usually used with other agents to counteract this effect
3. DANGEROUS when used with renal failure. The failing kidney cannot excrete extra magnesium, resulting in accumulation

4. examples:
a. hydroxide salt (magnesium hydroxide) MOM
b. carbonate salt (combination) Gaviscon
c. combination products: (alum & magn) Maalox, mylanta
C. calcium salts
1. may cause constipation
2. their use may result in kidney stones
3. long duration of acid action may cause increased gastric acid secretion (hyperacidity rebound)
4. often advertised as an extra source of calcium (Tums)
D. sodium bicarbonate
1. highly soluble
2. buffers the acidic properties of HCl
3. quick onset, but short duration
4. may cause metabolic alkalosis
5. sodium content may cause problems in patients with HF, HTN, or renal insufficiency
VI. Antacids and antiflatulents
A. used to relieve the painful symptoms associated with gas
B. several agents are used to bind or alter intestinal gas and are often added to antacid combination products
C. simethicone (mylicon)
1. alters elasticity of mucus-coated bubbles, causing them to break
2. used often, but there are limited data to support effectiveness
VII. Antacid side effects, are minimal and depend on the compound used
A. Alum & calcium: constipation
B. magnesium: diarrhea
C. calcium carbonate: produces gas and belching, often combined with simethicone.
VIII. Drug interactions
A. adsorption of other drugs to antacids (**do NOT administer with other drugs)
1. reduces the ability of the other drug to be absorbed into the body
B. chelation
1. chemical binding, or inactivation, of another drug
2. produces insoluble complexes
3. result: reduced drug absorption
C. Increased stomach pH
1. increased absorption of basic drugs
2. decreased absorption of acidic drugs
D. Increased urinary pH (opposite)
1. increased excretion of acidic drugs
2. decreased excretion of basic drugs
IX. Nursing Implications
A. Use with caution with other medications due to the many drug interactions
B. Most medications should be given 2-3 hours after giving an antacid
C. Antacids may cause premature dissolving of enteric-coated medication, resulting in stomach upset
D. Be sure that chewable tablets are chewed thoroughly, and liquid forms are shaken well before giving.
E. Administer with at least 8 oz of H2O to enhance absorption (except for rapid dissolve forms)
F. Caffeine, alcohol, harsh spices, and black pepper may aggravate the underlying GI condition
G. Monitor side effects:
1. nausea, vomiting, abd pain, diarrhea
2. with calcium containing products: constipation and acid rebound
H. Monitor for therapeutic response
1. notify health care provider if symptoms are not relieved
I. Assess for allergies and preexisting conditions that may restrict the use of antacids, such as:
1. fluid imbalances, renal disease, heart failure
2. pregnancy
3. GI obstruction
J. Pts with heart failure or HPN should use low-sodium antacids such as Riopan, Maalox, or Mylanta II.



Which of the following would we give to a:
Renal insufficient patient? Basajel (aluminum salt alone)
A female who require extra calcium? Tums
A 33 y/o male suffering from gastric acidity (a regular person)? Mylanta/Maalox

What is true of sodium bicarbonate?
Should be used sparingly in renal insufficiency.