Cancer patients receiving a particularly strong form of chemotherapy treatment will soon have another weapon against one of the most common and potentially debilitating side effects of their therapy: nausea and vomiting.

The Food and Drug Administration has approved the drug Emend (aprepitant), manufactured by Merck, to help control the nausea and vomiting that can set in 24 to 48 hours after chemotherapy is administered and which can last up to five days.

“It should improve cancer patients’ quality of life, as well as their ability to tolerate these treatments,” FDA commissioner Mark McClellan, MD, PhD, said in a statement.

Nausea and vomiting caused by chemotherapy can be severe, according to Terri Ades, RN, director of quality of life and health promotion strategy at the American Cancer Society. A patient may be unable to hold down any food, or even fluids. In extreme cases, dehydration and weight loss can result.

Patients who experience this side effect may become so distressed they decide to stop the chemotherapy, Ades said.

“We hear it often – the side effects of treatment are worse than the disease,” she said. “That’s why new drugs for controlling nausea and vomiting are important. They make it less likely the patient will consider stopping treatment.”

Drugs developed over the past 20 years have helped control this side effect for many chemotherapy patients, Ades said, but few are very effective against the delayed-onset nausea Emend is designed to treat.

This type of nausea is common with certain strong chemotherapy drugs, including high-dose cisplatin, which are used to treat lung cancer, head and neck cancer, and some other cancers.

Emend is the first medicine approved specifically to treat this delayed-onset nausea, according to the manufacturer.

Patients will take three Emend pills over three days: one pill about an hour before chemotherapy, a second pill the day after chemotherapy, and a third pill the following day. Patients will also be given two other drugs, which have been the standard anti-nausea treatment until now, along with Emend.

Emend works by blocking a chemical substance that transmits nausea and vomiting signals to the brain, according to Merck. Because this mechanism is different from the way other anti-nausea medicines work, the combination of the three drugs provides better protection, the company said.

The FDA based its approval of the drug on two large clinical trials involving more than 1,000 cancer patients. In both studies, half the patients took the standard two-drug anti-nausea therapy, and half took the standard therapy plus Emend.

In each of the studies, Emend kept about 20% more patients nausea-free for up to five days following chemotherapy.

Emend may interact with blood thinners, the FDA said, so people on those medications should be tested regularly to be sure their dosage doesn’t need to be adjusted. Emend may also reduce the effectiveness of birth control pills.

Merck said Emend should be available in pharmacies (by prescription only) by April 14. A regimen of three pills will cost $250.

The costs should be covered by insurance.

Merck said it has a program to help patients who cannot afford Emend; information is available by calling 1-866-EMEND-RX (363-6379).