58
Drugs affecting
gastrointestinal motility
Learning objectives
Upon completion of this chapter, you should be able to:
1.
Describe the underlying processes in diarrhoea and constipation and correlate them with the types of drugs
used to treat these conditions.
2.
Describe the therapeutic actions, indications, pharmacokinetics, contraindications and cautions,
most common adverse reactions and important drug–drug interactions associated with laxatives and
antidiarrhoeal drugs.
3.
Discuss the use of laxatives and antidiarrhoeal agents across the lifespan.
4.
Compare and contrast the prototype laxatives and antidiarrhoeals with other agents in their class and with
other classes of laxatives and antidiarrhoeals.
5.
Outline the care considerations, including important teaching points, for people receiving laxatives and
antidiarrhoeal agents.
Glossary of key terms
antidiarrhoeal drug:
drug that blocks the stimulation of the gastrointestinal (GI) tract, leading to decreased activity and increased
time for absorption of needed nutrients and water
bulk stimulant:
agent that increases in bulk, frequently by osmotic pull of fluid into the faeces; the increased bulk stretches the GI wall,
causing stimulation and increased GI movement
cathartic dependence:
overuse of laxatives that can lead to the need for strong stimuli to initiate movement in the intestines; local
reflexes become resistant to normal stimuli after prolonged use of harsher stimulants, leading to further laxative use
chemical stimulant:
agent that stimulates the normal GI reflexes by chemically irritating the lining of the GI wall, leading to increased
activity in the GI tract
constipation:
slower-than-normal evacuation of the large intestine, which can result in increased water absorption from the faeces
and can lead to impaction
diarrhoea:
more-frequent-than-normal bowel movements, often characterised as fluid-like and watery because not enough time for
absorption is allowed during the passage of food through the intestines
lubricant:
agent that increases the viscosity of the faeces, making it difficult to absorb water from the bolus and easing movement of
the bolus through the intestines
Test your current knowledge of drugs affecting gastrointestinal motility with a PrepU Practice Quiz!
LAXATIVES
Chemical stimulants
bisacodyl
senna
Bulk stimulants
lactulose
psyllium
sodium chloride-sodium
bicarbonate-potassium
chloride solution
Lubricants
docusate
glycerol
liquid paraffin
Other laxatives
methylnaltrexone
ANTIDIARRHOEALS
bovine colostrum
loperamide
opium derivatives
Ulcerative colitis drugs
balsalazide
mesalazine
olsalazine
IRRITABLE BOWEL SYNDROME
DRUGS
hyoscine
mebeverine
peppermint oil
