904
P A R T 1 1
Drugs acting on the gastrointestinal system
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Agents affecting gastrointestinal secretion include
H
2
antagonists, antacids, proton pump inhibitors,
GI protectants and prostaglandins. Digestive enzymes
replace missing GI enzymes.
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Among the most common complaints addressed in
clinical practice are GI symptoms.
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Increased acid production, decrease in the protective
mucus lining of the stomach, infection with
Helicobacter pylori
bacteria, or a combination of
these is the likely cause of peptic ulcers.
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H
2
antagonists block the release of acid in response
to gastrin or parasympathetic release; adverse effects
can include dizziness, confusion, cardiac arrhythmias
and galactorrhoea.
A
ntacids
Antacids
(Table 57.1) are a group of inorganic chemicals
that neutralise stomach acid. Antacids are available over
the counter, and many people use them to self-treat a
variety of GI symptoms. There is no one perfect antacid
(see Adverse effects). The choice of an antacid depends
on adverse effect and absorption factors. Available
agents are sodium bicarbonate, calcium carbonate, mag-
nesium salts and aluminium salts.
Therapeutic actions and indications
Antacids neutralise stomach acid by direct chemical
reaction (see Figure 57.1). They are recommended for
the symptomatic relief of upset stomach associated
with hyperacidity, as well as the hyperacidity associated
with peptic ulcer, gastritis, peptic oesophagitis, gastric
KEY POINTS
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Inspect the skin for evidence of lesions or rash
to monitor for adverse reactions.
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Evaluate neurological status, including orientation
and affect,
to assess CNS effects of the drug and to
plan for protective measures.
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Assess cardiopulmonary status, including
pulse, blood pressure and electrocardiogram
(if intravenous use is needed),
to evaluate the
cardiac effects of the drug.
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Perform abdominal examination, including
assessment of liver,
to establish a baseline and rule
out underlying medical problems.
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Monitor the results of laboratory tests, including
liver and renal function tests,
to predict changes
in metabolism or excretion of the drug that might
require dose adjustment.
Implementation with rationale
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Administer oral drug with or before meals and
at bedtime (exact timing varies with product)
to ensure therapeutic levels when the drug is most
needed.
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Arrange for decreased dose in cases of hepatic or
renal dysfunction
to prevent serious toxicity.
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Monitor the person continually if giving
intravenous doses
to allow early detection of
potentially serious adverse effects, including
cardiac arrhythmias.
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Assess the person carefully for any potential
drug–drug interactions if given in combination
with other drugs
because of the drug effects on
liver enzyme systems.
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Provide comfort, including analgesics, ready
access to bathroom facilities and assistance with
ambulation,
to minimise possible adverse effects.
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Periodically reorient the person and institute safety
measures if CNS effects occur
to ensure safety and
improve tolerance of the drug and drug effects.
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Arrange for regular follow-up
to evaluate drug
effects and the underlying problem.
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Offer support and encouragement
to help people
cope with the disease and the drug regimen.
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Provide teaching regarding drug name, dosage,
and schedule for administration; importance of
spacing administration appropriately as ordered;
need for readily available access to bathroom;
signs and symptoms of adverse effects and
measures to minimise or prevent them; danger
signs that necessitate notifying the healthcare
provider immediately; safety measures, such as
avoiding driving and asking for assistance when
ambulating, to deal with possible effects of
dizziness, somnolence or confusion; the need for
compliance with therapy to achieve the intended
results; and the importance of periodic monitoring
and evaluation, including laboratory testing,
to determine drug effectiveness and to enhance
knowledge about drug therapy and to promote
compliance.
Evaluation
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Monitor response to the drug (relief of GI
symptoms, ulcer healing, prevention of progression
of ulcer).
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Monitor for adverse effects (dizziness, confusion,
hallucinations, GI alterations, cardiac arrhythmias,
hypotension, gynaecomastia).
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Evaluate the effectiveness of the teaching plan
(person can name drug, dosage, adverse effects to
watch for and specific measures to avoid them).
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Monitor the effectiveness of comfort measures and
compliance with the regimen.
