senna, docusate sodium)
■ Bulk forming laxatives (ispaghula husk) ■ Faecal so eners (docusate sodium).
ere are many similarities between the classes
in terms of metabolism and side-e ects. In general, laxatives, regardless of class, are not appreciably absorbed from the gastrointestinal tract except senna, which is absorbed and excreted by the liver, and therefore only one dose per day is required.
Side e ects
Common side e ects include abdominal distension and pain, borborygmi, nausea and vomiting, atulence and diarrhoea. Laxative dependence has not been seen in children. Laxatives should not be used in the presence of intestinal in ammation, perforation or obstruction. Again, laxatives are largely free of drug interactions, although there may be transient reduced absorption of other medications because of increased gut motility.
NICE (2010) recommends treatment that is centred around the use of stimulant and osmotic laxatives, but it is useful to look at all the classes.
Osmotic laxatives
ese exert their action by drawing the water from the body via the digestive tract into the bowel and makes the stool wet. is increases the bulk of the stool as well as so ening it. Increased stool bulk triggers colon motility and passage of the stool. Dehydration can
be a problem and adequate uid intake is important. Electrolyte imbalance is also possible, with sodium and potassium being drawn into the gut with the water.
Macrogol preparations are recommended by
NICE (2010) as the rst line of treatment. Macrogol preparations are a slightly di erent class: iso-osmotic laxatives retain water in the bowel rather than drawing it from the body, so there is no net movement of
water to or from the digestive tract. All formulations available in the UK include added potassium and sodium to minimize the movement of electrolytes across the digestive tract. Movicol Paediatric Plain
is the only licensed preparation that can be used in children under 12 years of age (NICE, 2010). Previous studies have shown that it can be used safely and e ectively in children under 2 years, although it is
not licensed for this age group (Malakounides and Clayden, 2008).
Side-e ects of macrogols are no di erent from those expected. ere is an additional contra- indication against its use in patients with severe in ammatory bowel disease, such as Crohn’s disease.
e most common osmotic laxative in children is lactulose. However, lactulose has been shown to be less e ective than macrogols (Voskeiyl, 2004) and takes at least 48 hours to have an e ect. Its advantage is that it is licensed from 1 month of age. Again,