After several years' litigation, recently Pfizer regained the patent of Viagra (Sildenafil Citrate Tablets) in China, stopping a dozen Chinese firms from selling cheaper copies. Beijing highest court made the final decision that the patent of Viagra is valid and Chinese enterprises can't produce Sildenafil Citrate until 2014 after the expiration of the patent.
On September 19th 2001, the State Intellectual Property Office (SIPO) awarded Viagra the patent certificate, but 12 Chinese enterprises jointly appealed to the Patent Review Committee of the SIPO to judge the patent invalid. On July 5th 2004, the Patent Review Committee made a decision the patent was invalid, then Pfizer appealed to a Beijing court on September 28th 2004. The Beijing court overturned the decision by Patent Review Committee on July 2006 , but the 12 Chinese enterprises can't accept the decision then appealed to Beijing highest court. In September Beijing highest court made the final decision.
"We see the decision as a promise that China should effectively protect intellectual property," Pfizer said. "The decision should give more confidence to the enterprise which want to invest in China."