Drug Interactions between dihydrocodeine / guaifenesin and sodium polystyrene sulfonate

MONITOR: Coadministration with medications that can cause constipation such as opioids may increase the risk of intestinal injuries associated with the use of sodium polystyrene sulfonate. Cases of intestinal necrosis, which may be fatal, and other serious gastrointestinal adverse events including bleeding, ischemic colitis, and perforation have been reported during treatment with sodium polystyrene sulfonate. Most cases occurred during concomitant use of sorbitol, and risk factors were present in many of the patients including prematurity, history of intestinal disease or surgery, hypovolemia, and renal insufficiency or failure. Data are limited in the medical literature regarding concomitant use of sodium polystyrene sulfonate and opioids. In one case report, intestinal obstruction occurred in an 86-year-old man who received sodium polystyrene sulfonate 15 g orally once daily for 4 days while also being treated with aluminum hydroxide 5 mL four times daily and slow-release morphine 10 mg three times daily. Although the interaction is primarily attributed to concretions of aluminum hydroxide in the intestine, the potential contribution of morphine is unknown.

MANAGEMENT: Because opioids commonly cause constipation, caution is advised when used during treatment with sodium polystyrene sulfonate. The prescribing information recommends avoiding the use of sodium polystyrene sulfonate in patients who are at risk for developing constipation or impaction, including those with a history of impaction, chronic constipation, inflammatory bowel disease, ischemic colitis, vascular intestinal atherosclerosis, previous bowel resection, or bowel obstruction, as well as those who have not had a bowel movement post-surgery. If clinically significant constipation develops, treatment with sodium polystyrene sulfonate should be discontinued until normal bowel motion is resumed. Concomitant administration of sorbitol is not recommended.