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P A R T 1 1
Drugs acting on the gastrointestinal system
■■
Antacids are used to chemically react with and
neutralise acid in the stomach. They can provide
rapid relief from increased acid levels. They are
known to cause GI alterations such as diarrhoea or
constipation and can alter the absorption of many
drugs.
■■
Acid rebound occurs when the stomach produces
more gastrin and more acid in response to lowered
acid levels in the stomach, which commonly occurs
with the use of antacids. Balancing the reduction of
the stomach acid without increasing acid production
is a clinical challenge.
P
roton pump
inhibitors
Proton pump inhibitors
(Table 57.1) suppress the secre-
tion of hydrochloric acid into the lumen of the stomach.
Five proton pump inhibitors are presently available:
omeprazole (
Losec
), esomeprazole (
Nexium
), lansopra-
zole (
Zopral, Zoton
), pantoprazole (
Ozpan, Pantoloc
)
and rabeprazole (
Pariet, Prabez
).
Therapeutic actions and indications
The gastric acid pump or proton pump inhibitors
suppress gastric acid secretion by specifically inhibit-
ing the hydrogen–potassium adenosine triphosphatase
(H
+
, K
+
-ATPase) enzyme system on the secretory surface
of the gastric parietal cells. This action blocks the final
step of acid production, lowering the acid levels in the
stomach (see Figure 57.1). They are recommended for
the short-term treatment of active duodenal ulcers,
GORD, erosive oesophagitis and benign active gastric
ulcer; for the long-term treatment of pathological hyper-
secretory conditions; as maintenance therapy for healing
KEY POINTS
status of pregnancy or breastfeeding
due to
possible effects on the fetus or newborn.
■
■
Perform a physical examination
to establish
baseline data before beginning therapy, determine
the effectiveness of the therapy, and evaluate for
any potential adverse effects associated with drug
therapy.
■
■
Inspect the abdomen. Auscultate bowel sounds
to ensure GI motility.
■
■
Assess mucous membrane status
to evaluate
potential problems with absorption and hydration.
■
■
Monitor laboratory test results, including serum
electrolyte levels and renal function tests,
to
monitor for adverse effects of the drug and
potential alterations in excretion that may
necessitate dose adjustment.
Implementation with rationale
■
■
Administer the drug apart from any other oral
medications approximately 1 hour before or
2 hours after
to ensure adequate absorption of the
other medications.
■
■
Have the person chew tablets thoroughly and
follow with water
to ensure that therapeutic levels
reach the stomach to decrease acid.
■
■
Obtain specimens for periodic monitoring of serum
electrolytes
to evaluate drug effects.
■
■
Assess the person for any signs of acid–base or
electrolyte imbalance
to ensure early detection and
prompt intervention.
■
■
Monitor the person for diarrhoea or constipation
to institute a bowel program before severe effects
occur.
■
■
Monitor the person’s nutritional status if diarrhoea
is severe or constipation leads to decreased food
intake
to ensure adequate fluid and nutritional
intake to promote healing and GI stability.
■
■
Offer support and encouragement
to help the
person cope with the disease and the drug regimen.
■
■
Provide thorough teaching, including the drug
name and prescribed dosage; schedule for
administration; signs and symptoms of adverse
effects and measures to minimise or prevent them;
warning signs that may indicate possible problems
and the need to notify the healthcare provider
immediately; the importance of maintaining fluid
and nutritional intake if diarrhoea or constipation
occurs; possible bowel training programs to deal
with constipation or diarrhoea if severe; cautions
related to prolonged chronic use of drug and
increased risk for acid rebound; the importance
of checking with the healthcare provider before
using any OTC medications; differences associated
with the various OTC antacid formulations; and
the need for periodic monitoring and evaluation
to enhance knowledge about drug therapy and to
promote compliance.
Evaluation
■
■
Monitor response to the drug (relief of GI
symptoms caused by hyperacidity).
■
■
Monitor for adverse effects (GI effects, imbalances
in serum electrolytes and acid–base status).
■
■
Evaluate the effectiveness of the teaching plan
(person can name the drug and dosage, as well
as describe adverse effects to watch for, specific
measures to avoid them and measures to take to
increase the effectiveness of the drug).
■
■
Monitor the effectiveness of comfort measures and
compliance with the regimen.
