Therapeutic Reviews Stimulant Laxatives and Opioid-Induced Constipation

Choice of Laxatives The prescription of laxatives is influenced by marketing, fashion, availability and cost, and there is wide variation in their use among clinicians and across countries.1,2 With the availability of polyethylene glycols (macrogols) and the more recently introduced ethylnaltrexone, it is even more important that clinicians understand both the pathophysiology of opioid-induced constipation, and the predominant mechanisms of action of commonly prescribed laxatives.3,4 Based on this understanding, clinicians should develop a simple, logical and cost-effective approach which optimizes the dose of a stimulant laxative and avoids the concurrent prescription of multiple different types of laxatives as far as possible.5e8 Because of its wide availability, low cost and recently published data, the example protocol at the end of this article recommends the initial use of senna alone.9,10 Constipation and Advanced Illness Constipation is common in advanced illness.11,12 The key feature is reduced water in the feces, which results in the passage of hard feces infrequently and with difficulty. Fecal dehydration occurs because of prolonged bowel transit time (allowing more absorption of water by the GI tract), or a reduced ability of the stool to retain water (because of reduced fiber content). Constipation is more common in immobile patients with small appetites and those receiving constipating drugs, particularly opioids.6,13 Opioids cause constipation by increasing ring contractions (segmenting activity), decreasing propulsive intestinal activity, and by enhancing the resorption of fluid and electrolytes.13,14 Whether or not tolerance occurs is unclear; however, opioid-related constipation generally persists in patients with advanced illness and its under-treatment is associated with a reduced quality of life, and may even result in opioid discontinuation. .........ceci est le début de l'article car il n'y a pas de résumé