The Royal Marsden Hospital Manual of Clinical Nursing Procedures - Lisa Dougherty [198]
Stimulant laxatives
Laxatives including bisacodyl, danthron and senna stimulate the nerve plexi in the gut wall, increasing peristalsis and promoting the secretion of water and electrolytes in the small and large bowel (Maestri-Banks 1998, Peate 2003, Shepherd 2000). Abdominal cramping may be increased if the stool is hard and a stool softener may be used in combination with this group of drugs (ABPI 1999, Taylor 1997). Long-term use of these laxatives should be avoided, except for patients on long-term opiates, as they may lead to impaired bowel function such as atonic non-functioning (cathartic) colon (ABPI 1999, Hinrichs and Huseboe 2001, Taylor 1997).
Preparations containing danthron are restricted to certain groups of patients, that is, the terminally ill as some studies on rodents have indicated a potential carcinogenic risk (ABPI 1999, Shepherd 2000, Taylor 1997). Danthron preparations should not be used for incontinent patients, especially those with limited mobility, as prolonged skin contact will colour the skin pink or red and superficial sloughing of the discoloured skin will occur (ABPI 1999, Taylor 1997).
Methylnaltrexone
Methylnaltrexone bromide is a parenteral preparation that is a peripherally acting selective antagonist of opioid binding to the mu-receptor, thus reversing peripherally mediated opioid-induced constipation but not centrally mediated analgesic effects (Thomas et al. 2008). The indications for use are opioid-induced constipation in patients with advanced illness receiving palliative care and who are unable to take oral laxatives. It is necessary to exclude bowel obstruction prior to its use and it should be used under the advice of a palliative care team.
Non-pharmacological support
Diet
Dietary manipulation may help to resolve mild constipation, although it is much more likely to help prevent constipation from recurring. Increasing dietary fibre increases stool bulk, which in turn improves peristalsis and stool transit time. This results in a softer stool being delivered to the rectum (Norton 1996b). The government’s strategy on food and health aims to increase the UK average daily fibre intake from the current 13.8 to 18.0 g (this recommended amount is based on the Englyst method; British Nutrition Foundation 2004, DH 1998).
There are two types of fibre: insoluble fibre is contained in foods such as wholegrain bread, brown rice, fruit and vegetables and soluble fibre is contained in foods such as oats, pulses, beans and lentils. It is recommended that fibre should be taken from a variety of both soluble and insoluble foods and eaten at times spread throughout the day (British Nutrition Foundation 2004, Edwards et al. 2003, Food Standards Agency 2006, Teahon 1999). Care should be taken to increase dietary fibre intake gradually as bloating and abdominal discomfort can result from a sudden increase, particularly in the older person and those with slow-transit constipation (Bush 2000, Cummings 1994, Edwards et al. 2003, Norton 1996a). Other sources of dietary laxatives can be encouraged with care; for example, prunes contain diphenylisatin and onions contain indigestible sugars (Norton 1996a).
Dietary changes need to be made in combination with other lifestyle changes. Daily fluid intake should be between 2.0 and 2.5 litres (Day 2001, Taylor 1997, Teahon 1999). Fruit juices such as orange and prune juice can help stimulate bowel activity (Winney 1998) and coffee has been shown to stimulate colonic motor and bowel activity (Addison 1999, Brown et al. 1990). The motor response takes place within minutes of drinking coffee and can last for up to 90 minutes (Addison 2000a).
There is a need for further studies to examine the role of dietary manipulation in the management of constipation, particularly the function of dietary fibre and fluid intake (Addison 2000b).