Drugs acting on the gastrointestinal tract. II Motility and secretions

CC RnCOSTEi 0IP hydrocortisone prednisolone suppositories, enemas, foam) oral prednisolone 

Muscular conuactiotisi ot Lite gut and secretion of acid and cn/ymes are under autonomic control. 11te enteric part of the autonomic nervous system consists of gunglionated plexuses ( ) with complex inter-connections supplying the smooih muscle, mucosa and blood vessels, fhe ganglia t (pstrasytnpatheiic) receive extrinsic excitatory fibres from the vagus and inhibitory sympathetic fibres. Other transmitters in the gut include 5HT. Al P. nitric oxide and neuropeptide-Y. 

Anti-inflammatory corticosteroids and luninosal icy tales (top left) arc used in ulcerative colitis and Crohn s disease. To reduce the need for systemic steroid.s, it is usual to add azathloprine. an immunosup-pressam (Chapter 45). 

Constipation is characteriited by abdominal di scorn t o if, loss of appetite and malaise resullitig from insufficient frequency of defaecation this results in abnormally hard and dry faeces. The frequency and volume of defaecation are best regulated by diet, but drugs may be needed for specifie purposes (e.g. before surgery of the colon or redum colonoscopy). 

Bulk laxatives increase the volume of the intestinal contents, stimulating peristalsis. They include indigestible polysaccharides such as cellulose (bran) and ispaghula. Osmotic laxatives increase hulk in the bowel by retaining water by an osmotic effect. They include salts containing iMorly absorbed tons (e.g. Epsom sait.s) and laetiilo.se, 

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Drugs acting on the gastrointestinal tract. II Motility and secretions... 

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