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Chapter 50
Acid-Controlling Drugs
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Acid-Related Pathophysiology

The stomach secretes:

Hydrochloric acid (HCl)
 Bicarbonate
 Pepsinogen
 Intrinsic factor
 Mucus
 Prostaglandins
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Glands of the Stomach



Cardiac
Pyloric
Gastric

The cells of the gastric gland are the largest in
number and of primary importance when discussing
acid control
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Cells of the Gastric Gland





Parietal
Chief
Mucous
Endocrine
Enterochromaffin
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Cells of the Gastric Gland (cont’d)

Parietal cells


Produce and secrete HCl
Primary site of action for many of the drugs used to
treat acid-related disorders
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Parietal Cell Stimulation and
Secretion
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Cells of the Gastric Gland

Chief cells

Secrete pepsinogen, a proenzyme
 Pepsinogen becomes pepsin when activated by
exposure to acid
 Pepsin breaks down proteins (proteolytic)
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Cells of the Gastric Gland (cont’d)

Mucous cells



Mucus-secreting cells (surface epithelial cells)
Provide a protective mucus coat
Protect against self-digestion by HCl and digestive
enzymes
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Hydrochloric Acid




Secreted by parietal cells when stimulated by
food, caffeine, chocolate, and alcohol
Maintains stomach at pH of 1 to 4
Acidity aids in the proper digestion of food and
defenses against microbial infection via the GI
tract
Secretion also stimulated by:


Large fatty meals
Emotional stress
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Acid-Related Diseases

Peptic ulcer disease (PUD)


Gastric or duodenal ulcers that involve digestion of
the GI mucosa by the enzyme pepsin
Helicobacter pylori (H. pylori)


Bacterium found in GI tract of 90% of patients with
duodenal ulcers and 70% of those with gastric ulcers
First-line therapy includes a 10- to 14-day course of a
proton pump inhibitor and antibiotics
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Acid-Related Diseases (cont’d)

Stress-related mucosal damage



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GI lesions are a common finding in ICU patients,
especially within the first 24 hours after admission
Factors include decreased blood flow, mucosal
ischemia, hypoperfusion, and reperfusion injury
Nasogastric (NG) tubes and ventilators predispose
patients to GI bleeding
A histamine receptor–blocking drug or a proton pump
inhibitor are given for prevention
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Types of Acid-Controlling Drugs



Antacids
H2 antagonists
Proton pump inhibitors
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Antacids



Basic compounds used to neutralize stomach
acid
Salts of aluminum, magnesium, calcium, and/or
sodium
Many antacid preparations also contain the
antiflatulent (antigas) drug simethicone
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Antacids: Mechanism of Action



Do not prevent the overproduction of acid but
instead help to neutralize acid secretions
Promote gastric mucosal defensive mechanisms
Stimulate secretion of:



Mucus: protective barrier against HCl
Bicarbonate: helps buffer acidic properties of HCl
Prostaglandins: prevent activation of proton pump
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Antacids: Drug Effects

Reduction of pain associated with acid-related
disorders

Raising gastric pH 1 point (1.3 to 2.3) neutralizes 90%
of the gastric acid
 Reducing acidity reduces pain as a result of:
• Base-mediated inhibition of the protein-digesting ability of
pepsin
• Increase in the resistance of the stomach lining to irritation
• Increase in the tone of the cardiac sphincter
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Antacids (cont’d)

Over-the-counter formulations available as:

Capsules and tablets
 Powders
 Chewable tablets
 Suspensions
 Effervescent granules and tablets
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Antacids (cont’d)

Used alone or in combination

Aluminum salts
 Magnesium salts
 Calcium salts
 Sodium bicarbonate
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Antacids: Aluminum Salts




Have constipating effects
Often used with magnesium to counteract
constipation
Often recommended for patients with renal
disease (more easily excreted)
Examples

Aluminum carbonate: Basaljel
 Hydroxide salt: AlternaGEL
 Combination products (aluminum and magnesium):
Gaviscon, Maalox, Mylanta, Di-Gel
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Antacids: Magnesium Salts


Commonly cause diarrhea; usually used with
other drugs to counteract this effect
Dangerous when used with renal failure—the
failing kidney cannot excrete extra magnesium,
resulting in accumulation
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Antacids: Magnesium
Salts (cont’d)

Examples



Hydroxide salt: magnesium hydroxide (Milk of
Magnesia)
Carbonate salt: Gaviscon (also a combination
product)
Combination products such as Maalox, Mylanta
(aluminum and magnesium)
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Antacids: Calcium Salts





Many forms, but carbonate is most common
May cause constipation, kidney stones
Also not recommended for patients with renal
disease—may accumulate to toxic levels
Long duration of acid action—may cause
increased gastric acid secretion (hyperacidity
rebound)
Often advertised as an extra source of dietary
calcium

Example: Tums (calcium carbonate)
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Antacids: Sodium Bicarbonate


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

Highly soluble
Buffers the acidic properties of HCl
Quick onset, but short duration
May cause metabolic alkalosis
Sodium content may cause problems in patients
with heart failure, hypertension, or renal
insufficiency
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Classroom Response Question
A patient who has chronic renal failure wants to
self-treat with an antacid for occasional heartburn.
Which medication is the best choice for this
patient?
A. A magnesium-containing antacid
B. A calcium-containing antacid
C. An aluminum-containing antacid
D. Because of renal problems, the patient should
not take antacids for this problem.
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Antacids and Antiflatulents


Antiflatulents: used to relieve the painful
symptoms associated with gas
Several drugs are used to bind or alter intestinal
gas and are often added to antacid combination
products

simethicone
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Antacids: Adverse Effects

Minimal and depend on the compound used



Aluminum and calcium
• Constipation
Magnesium
• Diarrhea
Calcium carbonate
• Produces gas and belching; often combined with simethicone
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Antacids: Drug Interactions

Adsorption of other drugs to antacids


Reduces the ability of the other drug to be absorbed
into the body
Chelation



Chemical binding, or inactivation, of another drug
Produces insoluble complexes
Result: reduced drug absorption
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Antacids: Drug Interactions (cont’d)

Increased stomach pH



Increased absorption of basic drugs
Decreased absorption of acidic drugs
Increased urinary pH


Increased excretion of acidic drugs
Decreased excretion of basic drugs
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Histamine 2 (H2) Receptor
Antagonists

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
Reduce acid secretion
All available over the counter in lower dosage
forms
Most popular drugs for treatment of acid-related
disorders




cimetidine (Tagamet)
nizatidine (Axid)
famotidine (Pepcid)
ranitidine (Zantac)
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H2 Antagonists:
Mechanism of Action




Competitively block the H2 receptor of acidproducing parietal cells
Reduced hydrogen ion secretion from the
parietal cells
Increase in the pH of the stomach
Relief of many of the symptoms associated with
hyperacidity-related conditions
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H2 Antagonists: Drug Effect
and Indications

Drug effect


Suppressed acid secretion in the stomach
Indications

Gastroesophageal reflux disease (GERD)
 Peptic ulcer disease (PUD)
 Erosive esophagitis
 Adjunct therapy to control upper GI bleeding
 Zollinger-Ellison syndrome
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H2 Antagonists: Adverse Effects




Overall, very few adverse effects
Central nervous system adverse effects in
elderly patients include confusion and
disorientation
Cimetidine may induce impotence and
gynecomastia
Thrombocytopenia has been reported with
ranitidine and famotidine
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H2 Antagonists: Drug Interactions

cimetidine (Tagamet)


Binds with P-450 microsomal oxidase system in the
liver, resulting in inhibited oxidation of many drugs
and increased drug levels
All H2 antagonists may inhibit the absorption of drugs
that require an acidic GI environment for absorption
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H2 Antagonists: Drug Interactions
(cont’d)


Smoking has been shown to decrease the
effectiveness of H2 blockers
For optimal results, H2 receptor antagonists are
taken 1 to 2 hours before antacids
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Classroom Response Question
When working with an elderly patient who has
been admitted for a possible gastrointestinal bleed,
the nurse identifies which drug as having the
potential to cause confusion and disorientation?
A.
B.
C.
D.
An antacid
A proton pump inhibitor
An H2 antagonist
A mucosal protectant
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Proton Pump Inhibitors (PPIs)



The parietal cells release positive hydrogen ions
(protons) during HCl production
This process is called the proton pump
H2 blockers and antihistamines do not stop the
action of this pump
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Proton Pump Inhibitors





lansoprazole (Prevacid)
omeprazole (Prilosec)
rabeprazole (AcipHex)
pantoprazole (Protonix)
esomeprazole (Nexium)
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Proton Pump Inhibitors:
Mechanism of Action



Irreversibly bind to H+/K+ ATPase enzyme
This bond prevents the movement of hydrogen
ions from the parietal cell into the stomach
Results in achlorhydria—ALL gastric acid
secretion is temporarily blocked

To return to normal acid secretion, the parietal cell
must synthesize new H+/K+ ATPase
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Proton Pump Inhibitors:
Indications



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GERD
Erosive esophagitis
Short-term treatment of active duodenal and
benign gastric ulcers
Zollinger-Ellison syndrome
Nonsteroidal antiinflammatory drug (NSAID)–
induced ulcers
Stress ulcer prophylaxis
Treatment of Helicobacter pylori–induced ulcers

Given with an antibiotic
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Proton Pump Inhibitors:
Adverse Effects





PPIs are generally well tolerated
Possible predisposition to GI tract infections
(Clostridium difficile)
Osteoporosis and risk of wrist, hip, and spine
fractures in long-term users
Pneumonia
Depletion of magnesium
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Miscellaneous Acid-Controlling
Drugs



sucralfate (Carafate)
misoprostol (Cytotec)
simethicone (Mylicon)
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Sucralfate (Carafate)




Cytoprotective drug
Used for stress ulcers, peptic ulcer disease
Attracted to and binds to the base of ulcers and
erosions, forming a protective barrier over these
areas
Protects these areas from pepsin, which
normally breaks down proteins (making ulcers
worse)
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Sucralfate (Carafate) (cont’d)





Little absorption from the gut
May cause constipation, nausea, and dry mouth
May impair absorption of other drugs—give
other drugs at least 2 hours before sucralfate
Do not administer with other medications
Binds with phosphate; may be used in chronic
renal failure to reduce phosphate levels
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Misoprostol (Cytotec)


Prostaglandin E analog
Prostaglandins have cytoprotective activity

Protect gastric mucosa from injury by enhancing local
production of mucus or bicarbonate
 Promote local cell regeneration
 Help to maintain mucosal blood flow
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Misoprostol (Cytotec) (cont’d)


Used for prevention of NSAID-induced gastric
ulcers
Doses that are therapeutic enough to treat
duodenal ulcers often produce abdominal
cramps, diarrhea
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Simethicone




Antiflatulent drug
Used to reduce the discomforts of gastric or
intestinal gas (flatulence)
Alters elasticity of mucus-coated gas bubbles,
breaking them into smaller ones
Result is decreased gas pain and increased
expulsion via mouth or rectum
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Classroom Response Question
Simethicone (Mylicon) is often combined with
calcium carbonate antacids because:
A. an increased antacid effect will result when these
drugs are given in combination.
B. simethicone helps to reduce the gas that is caused
by the calcium antacids.
C. simethicone reduces the diarrhea that is caused by
the calcium.
D. simethicone improves the taste of the calcium
tablets, which must be chewed.
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Nursing Implications: Antacids

Assess for allergies and preexisting conditions
that may restrict the use of antacids, such as:

Fluid imbalances
 Renal disease
 GI obstruction
 Heart failure (HF)
 Pregnancy

Patients with heart failure or hypertension
should not use antacids with high sodium
content
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Nursing Implications: Antacids
(cont’d)



Use with caution with other medications because
of the many drug interactions
Most medications should be administered 1 to 2
hours after an antacid
Antacids may cause premature dissolving of
enteric-coated medications, resulting in stomach
upset
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Nursing Implications: Antacids
(cont’d)


Be sure that chewable tablets are chewed
thoroughly, and liquid forms are shaken well
before giving
Administer with at least 8 ounces of water to
enhance absorption (except for “rapid-dissolve”
forms)
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Nursing Implications: Antacids
(cont’d)


Long-term self-medication with antacids may
mask symptoms of serious underlying diseases,
such as malignancy or bleeding ulcers
If symptoms remain ongoing, patient should
seek medical evaluation
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Nursing Implications: Antacids
(cont’d)

Monitor for adverse effects



Nausea, vomiting, abdominal pain, diarrhea
With calcium-containing products: constipation, acid
rebound
Monitor for therapeutic response

Notify health care provider if symptoms are not
relieved
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Nursing Implications: H2
Antagonists




Assess for allergies and impaired renal or liver
function
Use with caution in patients who are confused,
disoriented, or elderly
Take 1 to 2 hours before antacids
For intravenous doses, follow administration
guidelines
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Nursing Implications: Proton Pump
Inhibitors



Assess for allergies and history of liver disease
Not all are available for parenteral administration
May increase serum levels of diazepam and
phenytoin; may increase chance for bleeding
with warfarin
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Nursing Implications: Proton Pump
Inhibitors (cont’d)


The granules of pantoprazole capsules may be
given via nasogastric (NG) tubes, but the NG
tube must be at least 16 gauge or the tube may
become clogged
Capsule contents may be opened and mixed
with apple juice, but do not chew or crush
delayed-release granules
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Classroom Response Question
When providing education regarding the use of
proton pump inhibitors, which statement will the
nurse include?
A. “Take the medication along with the first meal of
the day.”
B. “Take the medication on an empty stomach, 30 to
60 minutes before eating.”
C. “Take the medication when you have symptoms of
heartburn.”
D. “Take the medication at bedtime with a snack.”
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