Candrilli SD, Davis KL, Iyer S. Impact of constipation on opioid use patterns, health care resource utilization, and costs in cancer patients on opioid therapy. J Pain Palliat Care Pharmacother. 2009 Sep 1;23(3):231-41.
Vallano A, Mendoza G, Rodríguez A, Rebordosa C. Seguridad de los analgesicos y de los antiinflamatorios. Farm Hosp. 2004;157:23-31.