Shanghai-listed drugmaker Topsun Science and Technology has agreed to sell some cough and cold medicine assets to Bayer Healthcare, a unit of the second largest drug company in Europe, for US$158 million as rising costs cripple margins. Topsun Science will sell the over-the-counter cough and cold portfolio of Topsun Science and Technology Qidong Gaitianli Pharmaceutical, a subsidiary of the listed firm, to Bayer's unit. The assets include the popular White & Black cold medicine and two other cough syrup brands. Bayer will pay 1.1 billion yuan for the production facilities and sales network of the three brands as well as 192 million yuan contingent payment related to business performance of those assets in future. Topsun Science said although revenue of China's over-the-counter western drug market is growing 16 per cent annually, production and sales costs are rising faster at 20 per cent. It will focus on Chinese medicine and narcosis drugs after the sale. Chinese medicine accounts for only about 25 per cent of China's drug market, said Guotai Junan in a research report in February. However, modern Chinese medicine has a lot of potential to grow, it said. Topsun Science's net profit for the first half this year rose 8.1 per cent to 20.7 million yuan. Shares of the company fell 2.07 per cent, closing at 11.34 yuan. The stock has surged 130 per cent this year.