Hyderabad: Dr Reddy's Laboratories on Thursday announced the launch of generic version of Allegra --Fexofenadine HCl -- tablets in the US market in an effort to tap USD 452 million Fexofenadine drug market.

The Food & Drug Administration (FDA) approved Dr Reddy's Abbreviated New Drug Application (ANDA) for Fexofenadine HCl tablets on April 12.

The pharmaceutical firm will market the over-the-counter (OTC) product under store brand labels in the US market.

The products are bio equivalent versions of Sanofi-Aventis' Allegra tablets which received Rx-to-OTC switch approval from the FDA on January 24.

In January, the US District Court of New Jersey cleared decks for Dr Reddy's Laboratories, India's second-biggest drug maker, to launch the generic version of Allegra-D 24 in US.

The US Court had also ordered Sanofi-Aventis and Albany Molecular Research, which had earlier obtained an injunction against launching of the drug, to post a security of USD 40 million with the Court towards the possibility that the injunction had been wrongfully granted.

Earlier, based on a request filed by AMRI and Sanofi-Aventis, the US District Court had granted a Preliminary Injunction on the launch of Allegra-D 24 (fexofenadine hydrochloride / pseudoephedrine hydrochloride 180 mg / 240 mg extended release tablet) in June last year.

In September 2009, AMRI filed a patent infringement lawsuit in the court against Dr Reddy's for infringement of one of AMRI's patents, related to the manufacturing process for the active ingredient in Allegra, Allegra-D 12, and Allegra-D 24 Hour.