Zelmac (known in the US as Zelnorm), a new drug for treating constipation predominant Irritable Bowel Syndrome (IBS) was put on the market in Mexico last week.

     The new medication was recently turned down for approval by the US Food and Drug Administration (FDA). It was expected to be approved for use in women only, and is the first drug developed specifically for treatment of constipating IBS.

     About 16 to 21 percent of Mexican citizens suffer from IBS. Zelmac is taken twice a day and treats symptoms of constipation, pain, and bloating.

     Zelmac works by activating the serotonin 4 receptor. The serotonin 4 receptor is responsible for motility, and how fast stool travels through the colon. In constipating IBS, colon motility is slowed, causing stool to build up in the colon. By activating the receptor, motility is increased, which prevents constipation.

     In a study of 1,500 women with IBS, those treated with Zelmac reported "significant improvement". The most common side affects where diarrhea and headache.