Review document of the Spanish Association of Neurogastroenterology and Motility on the management of opioid-induced constipation.

Opioid induced constipation is a rising problem due to the progressive increment in the prescription of opioids. By contrast to functional constipation, opioid-induced constipation is not a functional gut disorder, but a side effect of the use of opioids. Opioids produce constipation due to a decrease in gastrointestinal motility and a reduction in the gastrointestinal secretions. The treatment of OIC focuses on three basic pillars: optimizing opioid drug indication, preventing constipation onset, and treating it if it occurs. As with any other cause of constipation, lifestyle adjustments and laxatives should be the first-line treatment in the pharmacological management of OIC. Osmotic laxatives such as polyethylene glycol (PEG) are the agents of choice. PEG is inert and is neither fermented nor absorbed in the gastrointestinal tract. Furthermore, it has broad clinical applicability due to its favourable safety profile. If first-line treatments fail, peripheral mu receptor antagonists (PAMORA) are the drugs of choice. They reduce the peripheral effects of OIC with minimal potential to diminish analgesia or induce centrally mediated withdrawal syndrome. Different PAMORA are available in the market, both for oral and subcutaneous administration, with demonstrated efficacy for management of OIC in different clinical trials.