Dr Reddy’s Laboratories has suffered a setback with the news that a US court has blocked sales of the Indian drugmaker’s generic version of Sanofi-Aventis’ antihistamine Allegra.

Shares in the Hyderabad-based company fell after the US District Court of New Jersey granted a preliminary injunction brought by Sanofi and partner Albany Molecular Research related to Dr Reddy’s Abbreviated New Drug Application to market its version of Allegra D24 (fexofenadine/pseudoephedrine) extended-release tablets. In September last year, Albany Molecular sued, alleging infringement of patents related to the manufacturing process of the drug, which Sanofi holds the patents on.

Dr Reddy’s says it “strongly disagrees with the court’s decision and intends to appeal”. The Business Standard newspaper noted that analysts were expecting Dr Reddy’s to pocket $150 million in revenues in three years from its copycat version of Allegra D24 in the USA and the company was planning an 'at-risk' launch in the first quarter of 2011, since a patent litigation is also pending in the US court. The Indian firm’s generic was approved in March by the US Food and Drug Administration.

The newspaper notes that the patent for the main compound of Allegra expired in 2001, but with its various formulations, it has patent protection lasting up to 2014. Sanofi had also sued another Indian drugmaker, Wockhardt, in March, but Teva Pharmaceutical Industries has been selling its version of Allegra since the first quarter.

At the end of last year, Sanofi announced that it will seek to convert Allegra in the USA to an over-the-counter product.