Following objections from local drug manufacturers, China's State Intellectual Property Office (SIPO) has revoked the patent for Pfizer's Viagra, a drug that treats male erectile dysfunction, arguing that the original patent application did not reveal sufficient information about the active ingredients.

Paul Mooney describes how the move has generated concern among foreign companies, who are particularly worried that the details released in patent applications can make it easier to produce counterfeit versions of their drugs. Pfizer says 90 per cent of Viagra sold in China is fake.

Following a decision by SIPO's Patent Re-examination Board to revoke its patent on Viagra, Pfizer has filed an appeal to the Beijing First Intermediate People's Court. If the court rules against the company, experts say that more Chinese drug manufacturers may be encouraged to challenge foreign-held patents for the right to sell generic drugs on the domestic market. But Pfizer has hinted that, if adequate intellectual property protection is not in place, it could cut back on future investment in China.

Link to the full news article in The Scientist