C H A P T E R 5 7
Drugs affecting gastrointestinal secretions
909
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The gastric acid pump or proton pump inhibitors
suppress gastric acid secretion by specifically
inhibiting 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.
■■
Proton pump inhibitors are indicated for the short-
term treatment of active duodenal ulcer or active
benign gastric ulcer; treatment of heartburn or
symptoms of gastro-oesophageal reflux; treatment
of pathological hypersecretory syndromes; and
eradication of
H. pylori
infection as part of
combination therapy
GI
protectant
GI protectants
(Table 57.1) coat any injured area in the
stomach to prevent further injury from acid. Sucralfate
(
Carafate, Ulcyte
) is the only GI protectant currently
available.
Therapeutic actions and indications
Sucralfate forms an ulcer-adherent complex at duodenal
ulcer sites, protecting the sites against acid, pepsin and
bile salts. This action prevents further breakdown of the
area and promotes ulcer healing. The drug also inhibits
pepsin activity in gastric juices, preventing further break-
down of proteins in the stomach, including the protein
wall of the stomach (see Figure 57.1). See Table 57.1 for
indications.
Pharmacokinetics
Sucralfate is rapidly absorbed after oral administration,
metabolised in the liver and excreted in faeces. It crosses
the placenta and may enter breast milk.
Contraindications and cautions
Sucralfate should not be given to any person with known
allergy to the drug or any of its components
to prevent
hypersensitivity reactions
. It should not be given to
individuals with renal failure or undergoing dialysis
because a build-up of aluminium may occur if it is used
with aluminium-containing products.
Caution should
be used in women who are pregnant or breastfeeding
because of the potential adverse effects on the fetus or
neonate
.
Adverse effects
The adverse effects associated with sucralfate are pri-
marily related to its GI effects. Constipation is the
most frequently seen adverse effect. Diarrhoea, nausea,
KEY POINTS
indigestion, gastric discomfort and dry mouth may also
occur. Other adverse effects that have been reported
with this drug include dizziness, sleepiness, vertigo, skin
rash and back pain.
Clinically important drug–drug interactions
If aluminium salts are combined with sucralfate, there is
a risk of high aluminium levels and aluminium toxicity.
Extreme care should be taken if this combination is
used.
In addition, if phenytoin, fluoroquinolone antibiot-
ics (e.g. ciprofloxacin, norfloxacin), or penicillamine is
combined with sucralfate, decreased serum levels and
drug effectiveness may result. In such combinations,
the individual agents should be administered separately,
with at least 2 hours between drugs.
Prototype summary: Sucralfate
Indications:
Short-term treatment and maintenance
treatment of active duodenal ulcer; treatment
of oral and oesophageal ulcers due to radiation,
chemotherapy or sclerotherapy.
Actions:
Forms an ulcer-adherent complex at the
duodenal ulcer site, protecting the ulcer from acid,
bile salts and pepsin, promoting healing of the
ulcer; also inhibits pepsin activity in gastric juices.
Pharmacokinetics:
Route
Onset
Duration
Oral
30 mins
5 hours
T
1/2
:
6 to 20 hours; metabolised in the liver and
excreted in faeces.
Adverse effects:
Sleeplessness, dizziness, vertigo,
insomnia, rash, constipation, diarrhoea, nausea,
indigestion, dry mouth, back pain.
Care considerations for
people receiving a GI protectant
Assessment: History and examination
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■
Assess for
possible contraindications or cautions
:
any history of allergy to sucralfate
to prevent
hypersensitivity reactions
; renal dysfunction
or dialysis,
which can lead to a build-up of
aluminium
; and current status of pregnancy or
breastfeeding.
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■
Perform a physical examination
to establish
baseline data before beginning therapy, to
determine the effectiveness of therapy and to
evaluate for any adverse effects associated with
drug therapy.
