Zelnorm Receives Label Change
On April 28, 2004, the FDA announced the addition of newrisk information to the health professional labeling for Zelnorm(tegaserod maleate; Novartis Pharmaceuticals, East Hanover,NJ). This information includes a warning about diarrhea and aprecaution regarding ischemic colitis.
The overall occurrence of diarrhea observed in clinical trialswas 9% in the tegaserod group, compared with 4% in the controlgroup. Diarrhea usually occurred early in treatment andresolved with continued therapy; only 1.6% of patients in clinicaltrials discontinued therapy because of diarrhea.Yet, a smallpercentage of patients (0.04%) experienced serious consequencesof diarrhea, including hypovolemia, hypotension, andsyncope, which very rarely led to hospitalization. Therapyshould be discontinued if these events are observed.
Recent epidemiologic studies indicate that ischemic colitis, arare condition in which blood flow to the colon is insufficient tomeet its metabolic needs, occurs at a higher rate in patients withirritable bowel syndrome than in the general population. Postmarketingsurveillance of patients who take tegaserod, however,has yielded rare reports of ischemic colitis. No cases ofischemic colitis were observed with tegaserod in any of the clinicaltrials, which involved more than 7000 patients; there is noevidence of a causal relationship between tegaserod use andischemic colitis. Therapy should be discontinued and appropriatediagnostic tests conducted in patients who experience newor worsening abdominal pain or blood in the stool.