Drugs used to relieve muscle spasms in the intestine or to stimulate the passage of food through the digestive tract
Direct smooth-muscle relaxants
Antispasmodics and motility stimulants regulate the waves of muscular contraction that propel food through the digestive tract. Both these types of drug are used to treat conditions caused by abnormal muscle action in the digestive tract, including irritable bowel syndrome and diverticular disease. In some cases, these drugs may be used to relieve the symptoms of nonulcer dyspepsia. Motility stimulants are also used to treat gastro-oesophageal reflux disease, in which acidic stomach contents are regurgitated into the oesophagus.
Changes in diet, such as altering the amount of fibre eaten, may help to regulate intestinal contractions in people with conditions such as irritable bowel syndrome. Other changes in lifestyle, such as decreasing your alcohol intake and learning how to reduce stress, may also help. Your doctor may initially suggest that you make such changes to see whether they bring about an improvement. However, if self-help measures are not effective, your doctor may recommend that you take antispasmodic drugs or motility stimulants.
What are the types?
Antispasmodic drugs can be classified into two groups: direct smooth-muscle relaxants and anticholinergic drugs. Both types may be used to relieve the abdominal pain that occurs in gastrointestinal conditions such as irritable bowel syndrome and diverticular disease. Motility stimulants are sometimes given to relieve some of the symptoms caused by nonulcer dyspepsia and gastro-oesophageal reflux disease.
Direct smooth-muscle relaxants
These drugs have a direct action on the intestinal wall, which contains smooth muscle. Direct smooth-muscle relaxants work by causing the muscle to relax, thereby relieving painful intestinal cramps. The drugs are taken orally. Some preparations containing low doses of direct smooth-muscle relaxants are available over the counter. Some preparations contain a direct smooth-muscle relaxant combined with a bulk-forming agent. It is important to drink plenty of water if you are taking a direct smooth-muscle relaxant combined with a bulk-forming agent because otherwise an intestinal blockage may occur. In addition, you should not take these drugs before going to bed.
Direct smooth-muscle relaxants occasionally cause headache or nausea. Peppermint oil capsules can irritate the mouth or oesophagus; for this reason, they should always be swallowed whole with plenty of water.
These drugs help to reduce muscle spasm by lessening the transmission of nerve signals to the intestinal wall. They are usually taken orally and are available by prescription and also over the counter.
Side effects of anticholinergic drugs may include headache, constipation, a dry mouth, flushed skin, and blurred vision. These drugs may also cause difficulty in passing urine. Children and elderly people in particular are at risk of developing side effects.
Motility stimulants work primarily by causing the contents of the stomach to empty into the small intestine more rapidly than would otherwise happen. In this way, they help to prevent the occurrence of gastro-oesophageal reflux disease and relieve attacks of nonulcer dyspepsia. Motility stimulants also cause the muscular valve between the stomach and the oesophagus to close with more force. This also helps to prevent gastro-oesophageal reflux disease from occurring.
Motility stimulants are usually taken orally. They are available by prescription only. These drugs may cause a number of different side effects, including diarrhoea and drowsiness. Occasionally, metoclopramide and, very rarely, domperidone may cause uncontrollable muscle spasms, particularly of the face, tongue, mouth, and neck. These muscle spasms are more likely to occur in children and young adults, and are more likely with metoclopramide. For this reason, metoclopramide is not recommended for those under 20 years old. Metoclopramide and domperidone are also used to relieve nausea and vomiting (see Antiemetic drugs).
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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