A drug-making couple might become China's richest people after their company's initial public offering (IPO), the biggest in China's A-share market history, launched Thursday in Shenzhen. [Hurun China rich list 2009]

The shares of Shenzhen Hepalink Pharmaceutical Co. Ltd. priced at 73 times its 2009 earnings, or 148 yuan (21.67 U.S. dollars) per share, the most expensive IPO price on record for a Chinese stock.

The shares of Hepalink opened at 166 yuan (24.30 U.S. dollars) per share Thursday, up 18 yuan or 12.16 percent from the IPO price.

The founders, Li Li and his wife Li Tan, hold 288.04 million shares of the company, meaning their stake is worth 42.63 billion yuan (6.24 billion U.S. dollars) at the IPO price.

They set up the company in 1998.

The company produces heparin, a tissue extracted from intestines, lungs and livers of animals like pigs. It is used in open-heart surgery, dialysis, and for patients confined to bed to prevent blood clotting.

Wang Chuanfu, chairman of battery and electric car manufacturer BYD, was crowned China's richest person on the Hurun Rich List in late 2009, with an estimated worth of 35 billion yuan (5.12 billion U.S. dollars).