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Will generic Viagra transform China?

Chris Ratcliffe | Bloomberg | Getty Images

Viagra's patent in China has expired and some analysts expect cheaper prices will bring a surge of demand for the storied erectile dysfunction (ED) drug.

"China ED drugs market is an appealing cake with large profits," said Dr. Neil Wang, China managing director at Frost & Sullivan, in emailed comments. "The launch of generic alternatives into the market will lead to intense competition."

The size of the potential sales increase in China could be huge. Sales of ED drugs could triple to as much as 5 billion yuan ($810 million) by 2018 from an estimated 1.7 billion yuan in 2013, Citigroup estimated in a recent report.

It estimates Viagra, made by Pfizer, has around a 40-45 percent share of the ED drug market in tier one, two and three cities and it expects the generic version could take more than half of the market. Globally, Pfizer reported around $1.88 billion in Viagra sales in 2013.

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Cost is likely to be the main driver of increased sales, with the current 50-70 yuan per dosage price tag dissuading an estimated 30-40 percent of patients in China from taking ED drugs once they're prescribed, Citigroup said, noting the generic Viagra, also known as sildenafil citrate, will likely be priced at a 30-50 percent discount.

The target audience is fairly large and on the rise at around 10-25 percent of men aged 20 and above in China, Citigroup said, based on its interviews of "thought-leader urologists" and other surveys conducted in major cities in recent years.

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It isn't entirely clear why ED appears to be a growing problem, Citigroup said, but it cited possible reasons as growing work and life pressure, spreading pollution and unhealthy lifestyles including smoking, drinking and a high-fat diet.

"In addition, ED could be an early symptom of several major chronic diseases such as diabetes, hypertension, arteriosclerosis, and depression," it said.

The frequency of ED also increases with age. China's population is quickly going grey, with an estimated around 200 million people over the age of 60 and the number set to rise to over 400 million over the next 20 years -- higher than the population of the U.S. China's total population is estimated at around 1.39 billion.

To be sure, not everyone expects the generic version of the storied blue pill will make much difference to China's ED drug market, short-circuited by the country's rocky relationship with intellectual property.

"The availability of cheap knock-off or grey market products -- essentially the same formula -- is already pretty high," Ben Cavender, an analyst at China Market Research Group, told CNBC. "You can walk into any drugstore and get it for not a lot of money."

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Cavender also expects that most of the "recreational" users -- or those who fall into the "fun to try" rather than health-related categories -- will just continue to use grey-market products.

The cheaper pills also aren't likely to sway social attitudes on the mainland much, Dr. Wang said.

"Compared with Westerners, China's attitude towards sex is more conservative," Dr. Wang said, although he noted a gradual shift on views toward sex education is already underway, driven by growing affluence and exposure to foreign cultures.

China's efforts to nudge its birth-rate higher also aren't likely to get a fillip either, Cavender said. Late last year, China eased its one-child policy, in place since the 1970s, allowing couples to have two children, if one parent is an only child.

But Cavender doesn't believe health concerns have much to do with many couple's lack of interest in a second child.

"They want careers and extra income. They aren't rushing to have a second kid," he said.

Dr. Wang agreed. "The birth rate in China is significantly affected by economic affluence, popularization of education, urbanization and other factors," Wang said.

The first approved pills will likely hit the market by end-year, based on the filing status of an application from Guangzhou Baiyunshan Pharma, Citigroup said.

—By CNBC.Com's Leslie Shaffer; Follow her on Twitter @LeslieShaffer1