Huang Wenfang, a retiree in Shenyang, Liaoning province, said that since last January she hasn't been able to buy domestically made Tapazole in the city.

First diagnosed as a hyperthyroid patient eight years ago, Huang, 64, has been on treatment since then. But the price for a bottle of 100 tablets has increased from 1.7 yuan (28 US cents) to 2.5 yuan, she said. Imported versions cost more than 10 times that.

"I was so upset when I discovered that hospitals and drugstores were all out of the medication. Without it, I can't remain healthy," she said.

Before her treatment, she used to suffer from serious weight loss, anxiety, intolerance to heat, hair loss, muscle aches, weakness and severe fatigue.

"I used to weigh less than 40 kilograms," said Huang, who now weighs about 60 kg.

In recent months, patients from far-flung regions such as Wuxi, Jiangsu province, and Ankang, Shaanxi province, have begun to report shortages of imported Tapazole, according to media reports. Major hospitals in big cities, however, are not reporting any problems with supplies of imported Tapazole.

Xing Xiaoyan, a longtime doctor of endocrinopathy at the Sino-Japan Friendship Hospital in Beijing, said the hospital has never run out of Tapazole, though she admitted that it mainly provides the imported kind.

Mao said the 2009 medical reform may have created supply and demand problems, but that the health authority is working on a long-term solution.

"Under a market economy, all stakeholders need to cooperate and negotiate a balance to prevent similar problems from happening again in a bid to secure the drug supply," he said.