C H A P T E R 5 8
Drugs affecting gastrointestinal motility
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CHAPTER SUMMARY
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Laxatives are drugs used to stimulate movement
along the GI tract and to aid bowel evacuation.
They may be used to prevent or treat constipation.
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Laxatives can be chemical stimulants, which directly
irritate the local nerve plexus; bulk stimulants, which
increase the size of the food bolus and stimulate
stretch receptors in the wall of the intestine; or
lubricants, which facilitate movement of the bolus
through the intestines.
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Using proper diet and exercise, as well as taking
advantage of the actions of the intestinal reflexes, has
eliminated the need for laxatives in many situations.
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Cathartic dependence can occur with the chronic use
of laxatives, leading to a need for external stimuli for
normal functioning of the GI tract.
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GI stimulants act to increase parasympathetic
stimulation in the GI tract and to increase tone and
general movement throughout the GI system.
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Antidiarrhoeal drugs are used to soothe irritation
to the intestinal wall; block GI muscle activity to
decrease movement; or affect CNS activity to cause
GI spasm and stop movement.
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Drugs used to treat IBS are specific for the
main underlying complaint, either diarrhoea or
constipation, and a person’s selection must be
carefully matched to the effect of the drug.
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ONLINE RESOURCES
An extensive range of additional resources to enhance teaching
and learning and to facilitate understanding of this chapter may
be found online at the text’s accompanying website, located on
thePoint at
These include Watch and
Learn videos, Concepts in Action animations, journal articles,
review questions, case studies, discussion topics and quizzes.
WEB LINKS
Healthcare providers and students may want to consult
the following Internet sources:
Homepage of the Gastroenterological Society of
Australia. Information about a range of gastrointestinal
conditions.
Information on constipation—causes, diagnosis,
research, treatment and prevention across the lifespan.
Information for health professionals about traveller’s
diarrhoea.
Information for the traveller about maintaining good
health.
BIBLIOGRAPHY
Bisanz, A. (2007). Chronic constipation.
American Journal of
Nursing, 107(4)
, 72B–72H.
Farrell, M. & Dempsey, J. (2014).
Smeltzer & Bare’s Textbook of
Medical-Surgical Nursing
(3rd edn). Sydney: Lippincott Williams
& Wilkins.
Gage, H., Goodman, C., Davies, S. L., Norton, C., Fader, M.,
Wells, M., Morris, J. & Williams, P. (2010). Laxative use in care
homes
. Journal of Advanced Nursing, 66,
1266–1272.
Goodman, L .S., Brunton, L. L., Chabner, B. & Knollmann, B. C.
(2011).
Goodman and Gilman’s Pharmacological Basis of
Therapeutics
(12th edn). New York: McGraw-Hill.
McKenna, L. (2012).
Pharmacology Made Incredibly Easy
(1st Australian and New Zealand edn). Sydney: Lippincott
Williams & Wilkins.
McKenna, L. & Mirkov, S. (2014).
McKenna’s Drug Handbook for
Nursing and Midwifery
(7th edn). Sydney: Lippincott Williams
& Wilkins.
Nazarko, L. (2007). Managing diarrhoea in the home to prevent
admission.
British Journal of Community Nursing, 12(11)
,
508–512.
Hyoscine
Hyoscine (
Buscopan
), an anticholinergic agent that was
found to decrease GI spasm, was approved in 2001 as an
adjunctive therapy for the treatment of IBS.
Support and symptomatic relief remain the mainstays
of treating this disorder. Stress management and a
consistent relationship with a healthcare provider may
help to relieve some of the problems associated with this
common, although not entirely understood, disorder.
Mebeverine
Mebeverine (
Colese
,
Colofac
) has become a key drug
in managing IBS. It is an antispasmodic that relaxes
vascular, cardiac and other smooth muscle, including
that in the GI tract. It has some antimuscarinic activity,
although much less than atropine. It needs to be used
with caution in people with underlying cardiac, renal
or liver impairment. Mebeverine is not recommended
for use by women in the first trimester of pregnancy or
during breastfeeding.
Peppermint oil
Peppermint oil (
Mintec
) is readily available over-
the-counter and this preparation has been designed
specifically for managing IBS. Peppermint oil acts as an
antispasmodic, relaxing GI smooth muscle and reducing
gas production that also contributes to discomfort.
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BOX 58.5
Treating irritable bowel syndrome
