HARTFORD, Conn. – Yale researchers have developed a medication based on a Chinese herbal recipe more than 1,800 years old to counteract the adverse effects of chemotherapy.

The medicine, called PHY906, would relieve the gastrointestinal side effects of a common chemotherapy drug known as CPT-11, but not the drug’s effectiveness in fighting cancer cells. Lead researcher Yung-Chi Cheng, a professor of pharmacology at Yale, calls the medication “a marriage of Western and Eastern approaches to the treatment of cancer.”

CPT-11 is commonly prescribed with other chemotherapy agents. Its side effects cause a number of gastrointestinal ailments and are often treated with several different medications, with mixed results. The PHY906, the researchers say, tackled multiple side effects partly by reducing inflammation and creating new intestinal cells.

The medication was tested on mice that were undergoing chemotherapy. Those that were administered PHY906 showed less weight loss and more anti-tumor activity. Not only did it not compromise the chemotherapy medication’s effectiveness, the researchers said, it enhanced it.

“Herbal medicines, composed of multiple biologically active compounds, are widely claimed to help a variety of diseases,” the researchers write in the paper, which was published Wednesday in the journal Science Translational Medicine. “However, they have not been fully accepted by mainstream medicine because of the complex nature of the formulae, as well as a lack of stringent quality control.”

It is derived from a recipe of four plants called Huang Qin Tang, which was first described in Chinese medical literature about 1,800 years ago. Still used today, it is given to treat such gastrointestinal symptoms as diarrhea, nausea and vomiting.