The patents are for a key hypertension drug that sells under brand names Benicar and Benicar HCT or Olmitec and is one of its biggest money spinners globally. The first patent for Benicar HCT, a combination drug, was granted in October last year. The second patent for the method to manufacture the same drug was granted last week.

The patent grant means no Indian generics companies, which are experts in reverse-engineering patented drugs, will be able to make cheap generic versions of this drug in India for the next 20 years.

India adopted the product patent system in 2005, banning reverse engineering drugs patented after 1995.

Benicar has patent protection until 2016 in most of the geographies.

The drug belongs to a new group of hypertension drugs that defend blood vessels (arteries and veins) from angiotensin II, a natural substance that can cause high blood pressure.

Pfizer's Norvasc is the largest-selling drug in this category.

Patent experts said the company's third patent application is pending with the patent office. This is for Azor, a combination hypertension drug, for which Daiichi Sankyo received approval in the global markets only in 2007.

The Japanese company had recently sued the Hyderabad-based Matrix, which was taken over by the US based generics major Mylan Inc, for infringing a US patent on Azor.

Gopa Kumar G Nair, managing director, Patent Gurukul, said it seems Daiichi has not moved any patent application for the basic active ingredient, olmesartan medoxomil, and the patents awarded are for the products. So far none of the Indian companies are known to have filed an opposition so the patents are now valid.