Codeine phosphate (tablets) is the cheapest, effective antidiarrhoeal. It is only suitable for short-term use because of the risk of CNS side-effects and dependence.
Loperamide (capsules, syrup) may be used as an adjunct to rehydration in acute diarrhoea and for chronic diarrhoea in adults. It is less likely to cause central side-effects than codeine but is more expensive. It is unlikely to cause dependence.
PRESCRIBING POINTS FOR ANTIDIARRHOEAL DRUGS
- Antibiotics should not be given for acute diarrhoea with the exception of metronidazole where giardia infection is confirmed.
- Diarrhoea may require fluid and electrolyte replacement. This is particularly important in infants and in frail or elderly patients. For oral rehydration preparations.
- Patients with chronic diarrhoea need individualised treatment including dietary manipulation as well as drug treatment and maintenance of a liberal fluid intake. This will depend on underlying diagnosis.
- Antidiarrhoeal drugs which reduce gastro-intestinal motility should not be used in children.
- Antidiarrhoeal drugs should not be given to patients with acute colitis as they may cause toxic megacolon.
- Bulk-forming drugs, such as ispaghula are useful in controlling faecal consistency in ileostomy and colostomy patients, and in controlling diarrhoea associated with diverticular disease.
- Co-phenotrope (proprietary name, Lomotil®) is not recommended. The combination of diphenoxylate hydrochloride and atropine frequently causes side-effects. Overdosage is particularly dangerous in children.