Zhang, Xitian v. Shijiazhuang Ouyi Pharmaceutical Co., Ltd.

China (2007)

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Zhang, Xitian v. Shijiazhuang Ouyi Pharmaceutical Co., Ltd.

Beijing Higher People’s Court
China (2007)

RW

Facts

Prior art established that a chiral auxiliary known as DMSO could be used to separate amlodipine isomers from a chemical mixture. Xitian Zhang (plaintiff) obtained a Chinese patent for a separation process based on a related chiral auxiliary called DMSO-d6. Although DMSO-d6 was more expensive than DMSO, Zhang claimed that his DMSO-d6-based process produced better optical purity and yield than the DMSO-based process. Shijiazhuang Ouyi Pharmaceutical Company, Ltd. (Ouyi) (defendant) convinced China’s patent reexamination committee to revoke the patent. Ouyi produced evidence that the chemical similarities between DMSO and DMSO-d6 would lead anyone familiar with the prior art to conclude that DMSO-d6 could be used as an amlodipine separator. Ouyi’s evidence also included DMSO and DMSO-d6 test data, obtained under comparable laboratory conditions, which showed that the purity and yield produced using DMSO-d6 were only marginally better than what was obtainable using DMSO. After losing a preliminary appeal of the patent revocation, Zhang appealed to the Beijing Higher People’s Court.

Rule of Law

Issue

Holding and Reasoning ()

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