(Bloomberg) -- Zhong Huijuan quit her job teaching chemistry to teenagers and got into the drug business.

The career switch has paid off handsomely.

Her Hansoh Pharmaceutical Group Co., China’s largest maker of psychotropic drugs, is poised to go public Friday in Hong Kong with a market value of $10.4 billion. Zhong holds a 68% stake, giving her a $7.9 billion fortune, according to the Bloomberg Billionaires Index.

Zhong, 58, isn’t even the richest person in the family. Her husband Sun Piaoyang, 60, is worth $9.3 billion, thanks to the success of his Jiangsu Hengrui Medicine Co., a maker of anti-tumor drugs whose stock has returned about 16,300% since it went public in Shanghai almost two decades ago.

They’re poised to be among the world’s richest pharma families, with a combined fortune that rivals the Sacklers, who made a fortune selling opioids, and the Bertarellis of Switzerland.

Health-care spending in China has surged to 5.9 trillion yuan ($853 billion) last year from 3.5 trillion yuan in 2014, and is projected to top 9.4 trillion yuan in 2023, Hansoh said in a prospectus for the offering.

Cen Junda, a long-time investor of the Lianyungang, Jiangsu-based company, is also a billionaire with a stake valued at about $1.7 billion.

Iris Luo, a spokeswoman for Hansoh, declined to comment on their fortunes.

The IPO will make Zhong China’s third-richest woman, after two real estate moguls: Country Garden Holdings Co. co-Chairman Yang Huiyan, and Longfor Group Holdings Chairman Wu Yajun, who are worth $21.4 billion and $10 billion, respectively.

Zhong graduated with an undergraduate degree in chemistry from Jiangsu Normal University in July 1982 and taught chemistry at Yan’an middle school in Lianyungang in the early 1990s, according to the website of All-China Women’s Foundation. She founded Hansoh in 1995.

The company, which researches and produces drugs for six major therapeutic areas, reported 1.9 billion yuan in profit in 2018, an 18% increase from a year earlier, the prospectus shows. The drugmaker gets almost half of its revenue from cancer treatments.

“We believe its R&D will focus on making generics as soon as possible to take the first-mover advantage, a strategy many leading pharma companies applied in the past,” said Zhang Jialin, a Hong Kong-based analyst at ICBC International Research.

Hansoh’s cornerstone investors include Singapore’s sovereign wealth fund, GIC Pte, and Hillhouse Capital, Asia’s biggest private equity buyer, helping to draw more market interest in Friday’s IPO. The company said on Thursday that the retail portion of the offering was 12 times covered. Hengrui’s earlier success also may help bolster investor confidence in Hansoh.

“The synergies between Hengrui and Hansoh, particularly in R&D and distribution, will bring the latter advantages over industry competitors,” said Mia He, a Bloomberg Intelligence analyst.