Health Canada has revised prescribing information for the medication Rituxan after some people taking the drug for non-Hodgkin's lymphoma developed potentially life-threatening bowel obstruction or bowel perforation.

Rituxan is approved for use in Canada to treat non-Hodgkin's lymphoma (a cancer of the lymph nodes) and rheumatoid arthritis.

The drug's manufacturer, Hoffmann-LaRoche, said there have been two cases of bowel obstruction, including one death, and two cases of bowel perforation related to the use of Rituxan in Canada.

Bowel obstruction is a blockage of the small or large intestine and bowel perforation is a hole that develops in the small or large intestine.

A relationship between Rituxan and these events has not been clearly established, Health Canada noted.

"Patients taking Rituxan who experience abdominal pain, especially early in treatment, should contact their physician immediately," the department advised.

Generally, the average time for patients on the medication to develop bowel perforation was six days from the beginning of therapy, based on reports worldwide.

A global database showed 47 cases of bowel obstruction, including nine deaths, and 37 cases of gastrointestinal perforation, including four deaths, in patients taking Rituxan, the company said.

Most of the reports of bowel obstruction and perforation occurred in patients taking the drug for non-Hodgkin's lymphoma. Most patients had other underlying medical conditions and were undergoing other treatments such as chemotherapy, steroids and radiation therapy.

Signs and symptoms of bowel obstruction may include nausea, vomiting, abdominal swelling, abdominal pain, constipation or diarrhea.

Symptoms of gastrointestinal perforation include:

  • Sudden onset of abdominal pain (worsened by movement).
  • Abdominal tenderness.
  • High fever.
  • Chills.
  • Nausea.
  • Vomiting.

 "Bowel obstruction and perforation are serious conditions that require immediate medical attention," Health Canada said in the advisory, dated Nov. 10.

The drug was approved for sale in Canada in 2000.

With files from the Canadian Press