McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 5 8 Drugs affecting gastrointestinal motility

constipation, and a person’s selection must be carefully matched to the effect of the drug.

■■ BOX 58.5  Treating irritable bowel syndrome

CHAPTER SUMMARY ■■ 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. ■■ 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. ■■ 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. ■■ Cathartic dependence can occur with the chronic use of laxatives, leading to a need for external stimuli for normal functioning of the GI tract. ■■ GI stimulants act to increase parasympathetic stimulation in the GI tract and to increase tone and general movement throughout the GI system. ■■ 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. ■■ Drugs used to treat IBS are specific for the main underlying complaint, either diarrhoea or 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.

Knowing your strengths and weaknesses helps you to study more effectively. Take a PrepU Practice Quiz to find out how you measure up! 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 http://thepoint.lww.com. These include Watch and Learn videos, Concepts in Action animations, journal articles, review questions, case studies, discussion topics and quizzes. Healthcare providers and students may want to consult the following Internet sources: www.gesa.org.au Homepage of the Gastroenterological Society of Australia. Information about a range of gastrointestinal conditions. www.nlm.nih.gov/medlineplus/constipation.html Information on constipation—causes, diagnosis, research, treatment and prevention across the lifespan. www.racgp.org.au/afp/200504/200504kass.pdf Information for health professionals about traveller’s diarrhoea. www.smartraveller.gov.au/tips/travelwell.html Information for the traveller about maintaining good health. 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. WEB LINKS BIBLIOGRAPHY