Twelve Chinese pharmaceutical firms have launched an appeal against a court ruling protecting US drug giant Pfizer's patent rights to Viagra.

In a last-ditch effort to protect their investment in Viagra-type drugs, the firms yesterday lodged their appeal with the Beijing Higher People's Court.

They're calling for a reversal of the June 2 court ruling that upheld Pfizer's patent rights for its drug Viagra used in the treatment of impotency.

But the State Intellectual Property Office (SIPO), which was ordered on June 2 to withdraw its decision to invalidate the patent right of Viagra's active ingredient Sildenafil, didn't appeal by yesterday and missed the deadline.

On June 2 the Beijing No.1 Intermediate People's Court ruled in favor of Pzifer after reviewing the case for more than a year and a half.

Yesterday, while expressing his disappointment at not having SIPO's support in the appeal, Wang Wei, a lawyer representing the 12 companies, said: "We must try our best to protect our interests no matter whether or not SIPO will appeal."

The 12 companies from Jilin, Shanghai, Anhui, Jiangsu, Guangdong, Chongqing, Sichuan and Tianjin claim to have invested over 100 million yuan (US$12 million) in less expensive forms of the famous blue pill.

Pfizer filed a patent application in May 1994 for the use of Sildenafil in China.

SIPO granted the patent after seven years of examination but the 12 Chinese companies challenged the validity of that decision.

As a result SIPO's review board invalidated the patent in July 2004 on the grounds of "insufficient disclosure" of the treatment but the decision never took effect as Pfizer launched an immediate legal challenge.

Pfizer's legal action against SIPO reached court in October 2004. The case generated widespread interest although it was not the only case in which the SIPO patent review board, a government body, was in court for its decisions relating to intellectual property rights.

Industry insiders have pointed out that the huge potential profits of impotency drugs and clashes between domestic and overseas pharmaceutical companies were the real reasons for the dispute.

Chinese anti-impotency drugs, marketed under various names, are supposed to sell at less than 50 yuan (US$6.25) per pill, much cheaper than Viagra that costs around 100 yuan (US$12.5) per doze in China.

It is estimated that about 80 million Chinese men suffer from impotency problems. If Pfizer wins the patent dispute the Chinese drug makers will lose their investment completely. Sources with Pfizer would not comment on the appeal yesterday.

(China Daily June 20, 2006)