Hyderabad drug maker challenges patent on Tamiflu

Natco Pharma Ltd, a city-based generic drug maker, has challenged a patent on Tamiflu (Oseltamivir Phosphate) - a drug used in the treatment of bird and swine-flu infections, company officials said today.
    
Tamiflu was developed by Gilead, a California-based Bio-pharmaceutical research firm, which receives royalties on the drug's sale from Roche Holding AG.
    
Natco filed an Abbreviated New Drug Application (ANDA) with US FDA under Para-IV which necessitates the filer to inform the original inventor about the filing, the officials told PTI.
    
Natco, in its filing to US FDA, alleged that Gilead's patent on the drug is invalid and sent a notice to Gilead to that extent.
    
According to US patent laws, Gilead has 45 days time to file a patent infringement suit against the city-based drug firm seeking a 30-month ban on the new drug.
    
Oseltamivir Phosphate royalties from F Hoffmann-La Roche Ltd were $21.9 million in the fourth quarter of 2010, compared to Tamiflu royalties of $194.1 million in the fourth quarter of 2009.
    
Natco said the revenues from Tamiflu clocked global annual sales in the region of $1 billion.
    
The company is the 'first applicant' to file an ANDA for the generic version of Tamiflu and may be entitled to 180 days of generic market exclusivity after approval.
    
The company has tied up with the Luxemburg based Alvogen IPCO S.a.r.l. for marketing and sale of oseltamivir phosphate in the USA.
    
Gilead has the basic patent rights of Oseltamivir