WASHINGTON - The FDA's announcement last week of its intention to withdraw the approval of Hoechst Marion Roussel's Seldane (terfenadine) and Seldane D (terfenadine and pseudoephedrine), and a generic version of the antihistamine manufactured by Ivax Corp., in favor of HMR's Allegra (fexofenadine) has raised questions about what the agency will do in the future when other safer versions of approved drugs are approved.

The FDA action also may intensify the jockeying between Sepracor Inc. and HMR, which licensed U.S. rights to fexofenadine from SEPR, over worldwide marketing of the product. SEPR, which owns the use patent for the compound, believes the FDA decision has provided it with new leverage over the pharma company.