Pfizer has taken Ranbaxy Laboratories to court in the US, alleging infringement of its patent on Accupril (generic name: quinapril), an anti-hypertensive with annual sales of $550 million.
Teva of Israel had launched generic quinapril made by Ranbaxy in the US in December 2004.
The Ranbaxy spokesperson was not available for comment, though senior company functionaries confirmed the lawsuit had been filed. Repeated calls to Ranbaxy's US office yielded no response.
A CLSA Asia-Pacific Markets report said Pfizer filed the lawsuit in the district court of New Jersey on January 28, claiming Ranbaxy's quinapril formulation contained an ingredient that led to the infringement of a process patented by it.
It is learnt Pfizer has patented the use of lactose and microcrystalline cellulose for the stabilisation of quinapril.
Otherwise, it can degrade while tableting. In its lawsuit, Pfizer has claimed the quinapril made by Ranbaxy also uses microcrytalline cellulose, which is an infringement of its patent. Ranbaxy is yet to file a reply to the charges.
It is worth noting that Teva had earlier challenged the same process patent, which is valid till 2007. But the patent was upheld. Teva had gone on appeal against the decision. This prompted Teva to launch Ranbaxy's quinapril in the US. It is known to have captured a market of over 40 per cent since then.
Other pharmaceutical companies are also known to have launched their quinapril in the market.
About three years ago, Ranbaxy had also filed a patent application on stablising pharmaceutical compositions of ACE inhibitors like quinapril.
Ranbaxy's patent claims that one of the agents the company would use is microcrystalline cellulose. However, it is not clear if this patent has been granted.
Quinapril is not the only product over which Pfizer and Ranbaxy are locked in a legal battle. Ranbaxy has also challenged patents held by Pfizer on Lipitor, the world's largest selling drug with an annual turnover of $10 billion.
