Genzyme says petition against Renagel ‘inaccurate’

CAMBRIDGE, Mass.—A recent petition to the U.S. Food and Drug Administration calling for the withdrawal of Genzyme Corp.’s phosphorus drug Renagel was characterized as “inaccurate” by a Genzyme spokesman Friday.

“This is a deliberate attempt by a competitor to distort the safety profile of Renagel,” Genzyme spokesman Bo Piela told Renal Business Today. “We think [the petition] is grossly inaccurate and is a mischaracterization.”

Dr. Charles Nolan, a nephrologist with the University of Texas Health Sciences Center in San Antonio, filed a petition with the FDA May 4 alleging dialysis patients taking Renagel are at an increased risk of digestive-tract side effects and death.

“If it has this side effect, then it needs to be known,” Nolan told Bloomberg News Thursday. “I am shocked that this data is in the hands of the FDA and they don’t know about it.”

Nolan, who has served as a consultant for Nabi Pharmaceuticals, was not available for immediate contact. Nabi sells PhosLo, a rival drug to Genzyme’s Renagel. According to the petition, Nolan said he was not compensated by Nabi or anyone else for submitting the document.

In the document, Nolan said the FDA’s Adverse Event Reporting System database showed “a disturbing number of reports of intestinal obstructions and perforations associated with the use of Renagel in dialysis patients.”

The AERS is an information database that collects post-marketing safety data from voluntary sources regarding all approved drugs and therapeutic biologic products.

According to data presented in the petition, Renagel had 1,633 adverse events reported between January 2004 and September 2005. That number included 65 gastrointestinal obstructions and 68 GI perforations.

In comparison, Shire Pharmaceutical’s phosphate drug Fosrenol reported 354 adverse events, with three GI obstructions and zero GI perforations. PhosLo reported 21 adverse events with no GI obstructions or perforations, according to Nolan’s petition.

The FDA approved Renagel on Oct. 30, 1998, to reduce the level of phosphorus in end-stage renal disease patients on dialysis. According to the FDA, the drug should not be used in patients with low phosphorus levels or bowel obstruction.

Nolan has called on the FDA to withdraw Renagel’s approval. “If for some reason the [FDA] commissioner decides not to withdraw the approval of Renagel, the FDA should require a ‘black box warning’ about the risk of intestinal obstruction and perforation,” he wrote in the petition.

The petition is being funneled through the appropriate channels at the FDA, but no timetable has been set for further investigation, an FDA spokesman told Renal Business Today. The FDA, however, must respond to the petition within six months.

Piela said Genzyme has been in contact with the FDA and will provide any information needed for an investigation. He added that Renagel has been on the market for eight years and has proven its safety. “Renagel is one of the most thoroughly studied treatments in the market for end-stage renal disease patients.”

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