Watson confirms patent challenge for generic Renvela

MORRISTOWN, N.J. Generic drug maker Watson Pharmaceuticals is challenging the patent on a drug for treating kidney disease, Watson said Tuesday.

Watson announced that it had filed an approval application with the Food and Drug Administration for sevelamer carbonate tablets, a treatment for controlling serum phosphorus in patients with chronic kidney disease who are on dialysis. The drug is a generic version of Genzyme Corp.’s Renvela.

The application contained a Paragraph IV certification, a legal assertion under the provisions of the Hatch-Waxman Act of 1984 that the patent covering Renvela is invalid, unenforceable or won’t be infringed when Watson markets its generic version.

In response, Genzyme filed suit against Watson Monday in the U.S. District Court for the District of Maryland to prevent Watson from commercializing its version of the drug. The suit places a stay of final FDA approval for two and a half years or until the two companies resolve the case before the court.