Olmesartan (Benicar), Olmesartan+Hydrochlorthiazide (Benicar HCT) and Olmesartan+ Amlodipine (AZOR) formulations: Court upheld the validity of Key pat

Innovator company Daiichi Sankyo announced (in a press release Here) that the U.S. District Court in New Jersey has issued a decision in our U.S. patent litigation against Mylan (and its subsidiary Matrix) upholding the validity of our patent covering the Olmesartan (Benicar), Olmesartan+Hydrochlorthiazide (Benicar HCT) and Olmesartan+ Amlodipine (AZOR) formulations. Mylan was the first company to file ANDA application with a Paragraph IV certification against key patent covering Olmesartan and combinations. Subsequently, Innovator sued Mylan in New Jersey district court for the infringement of following key patent:

US5616599 (Expiry: Apr 25, 2016): The claim 13 covers Olmesartan Medoxomil as product (which was at issue during trial)

Mylan tried to invalidate the disputed patent based on obviousness grounds. Mylan alleged that Olmesartan is obvious in the light of Dupont company’s patent US5138069 and US5137902, which have priority over '599 patent.

Olmesartan is a structural analogue of Losartan and differ at two positions of imidazole ring. The 4-position of imidazole ring in losartan has chloro group (lipophilic group) whereas, Olmesartan has hydroxy propyl group (hydrophilic group), and in Losartan 5-position of imidazole ring has hydroxy methyl group, whereas, Olmesartan has carboxy group.

Importantly, the prior art teaches away from using hydrophilic group group at position-4 of imidazole ring, as said change resulted in lower activity. Also, formation of Medoxomil ester at 5-position of imidazole ring was not obvious to skilled person. Additionally, court considered commercial success of Olmesartan.

Based on above factors, court opined that Mylan failed to prove obviousness by clear and convincing evidence against ‘599 patent and concluded that disputed patent is neither invalid nor unenforceable.

Olmesartan medoxomil, an active ingredient in Benicar®, Benicar HCT® and AZOR®, is an angiotensin II receptor antagonist that Daiichi Sankyo independently developed, and is marketed in over 50 countries as an antihypertensive drug which suppresses vasoconstriction by affecting the rennin-angiotensin system to control blood pressure.