C H A P T E R 5 7
Drugs affecting gastrointestinal secretions
899
BOX 57.3
Drug therapy across the lifespan
Agents that affect gastrointestinal secretions
CHILDREN
The proton pump inhibitors, although not specifically
indicated for use in children, have been very successfully
used to decrease ulcer formation related to stress or
drug therapy. Dose should be determined by the age and
weight of the child.
Antacids may be used in children who complain of
upset stomach or who are receiving therapy known to
increase acid production; 5 to 15 mL every 1 to 3 hours
is usually an effective dose.
Special caution should be used with any of these
agents to prevent electrolyte disturbances or any
interference with nutrition, which could be especially
detrimental to children.
ADULTS
Adults should be cautioned not to overuse any of these
agents and to check with their healthcare provider if
gastrointestinal discomfort continues after repeated
use of any of these drugs. People should be monitored
for any electrolyte disturbances or interference with
the absorption or action of other drugs. If antacids are
used, they should be spaced 1 to 2 hours before or after
the use of other drugs. In 2005 and again in 2007, some
studies were published that linked prolonged use of
these agents with an increased incidence of colitis and
other gastrointestinal infections. Until further studies are
done, people should be advised to limit the use of these
agents.
PREGNANCY AND BREASTFEEDING
The safety of these drugs during pregnancy and
breastfeeding has not been established, so they should be
used with caution during pregnancy or breastfeeding.
Misoprostol is an abortifacient and should never be
used during pregnancy. Women of childbearing age who
use misoprostol should be advised to use barrier-type
contraceptives. Use of the other agents should be reserved
for those situations in which the benefit to the mother
outweighs the potential risk to the fetus.The drugs may
enter breast milk and also may alter electrolyte levels
or gastric secretions in the neonate. It is advised that
caution be used if one of these drugs is prescribed during
breastfeeding.
OLDER ADULTS
Older adults frequently are prescribed one or more of
these drugs. Older adults are more likely to develop
adverse effects associated with the use of these drugs,
including sedation, confusion, dizziness, urinary retention
and cardiovascular effects. Safety measures may be
needed if these effects occur and interfere with the
person’s mobility and balance. Because of changes that
occur within the GI tract with age, absorption of nutrients
can be affected when any of these drugs is used.The
use of proton pump inhibitors and H
2
blockers in older
adults has been associated with decreased absorption of
vitamin B
12
and the development of pernicious anaemia.
Older adults are also more likely to have renal
and/or hepatic impairment related to underlying medical
conditions, which could interfere with the metabolism and
excretion of these drugs.The dose for older adults should
be started at a lower level than recommended for younger
adults. People should be monitored very closely, and dose
adjustment should be made based on each individual’s
response.
These people also need to be alerted to the potential
for toxic effects when using OTC preparations that may
contain the same ingredients as many of these agents.
They should be advised to check with their healthcare
provider before beginning any OTC drug regimen.
Proton pump inhibitors may be the best choice for
treating gastro-oesophageal reflux disease in older people
because of fewer adverse effects and better therapeutic
response with these drugs.
TABLE 57.1
DRUGS IN FOCUS Drugs used to treat gastro-oesophageal reflux disease and ulcer disease
Drug name
Dosage/route
Usual indications
Histamine-2 antagonists
cimetidine (Tagamet)
200 mg PO t.d.s. at meals and 400 mg at
bedtime, or 800 mg PO at bedtime
Treatment of duodenal ulcer, benign
gastric ulcer, pathological hypersecretory
syndrome, gastro-oesophageal reflux
disease (GORD); prophylaxis of stress
ulcers; relief of symptoms of heartburn,
acid indigestion, sour stomach
Special considerations:
Not for children
<16 years old
famotidine (Pepcidine
Pamacid)
40 mg PO at bedtime
Treatment of duodenal ulcer, benign
gastric ulcer, pathological hypersecretory
syndrome, GORD; relief of symptoms of
heartburn, acid indigestion, sour stomach
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