Postinfectious irritable bowel syndrome (PI-IBS) is a common disorder wherein symptoms of IBS begin after an episode of acute gastroenteritis. Published studies have reported incidence of PI-IBS that ranged between 5% and 32%. Its high prevalence and the considerable effects on quality of life make PI-IBS a disease with high social cost. The majority of cases of PI-IBS meet the Rome II criteria for diarrhea-predo1ninant irritable bowel syndrome (IBS-D), with predominantly loose stool passed more frequently than normal and with urgency. The causes and underlying 1nechanis1ns of PI-IBS are still not fully understood, although it is believed that altered gut flora, changed intestinal permeability, activated gut immunity, and functional or structural changes in enteric nervous system are important factors. Recent studies have suggested that increased intestinal permeability could be an important factor in the sequence of events leading to low-grade intestinal inflammation and disturbed bowel function. Intestinal epithelial permeability is regulated by a complex protein system comprising tight junction (TJ) and adherens junction proteins. This increased permeability could be due to alterations of tight junction proteins. In addition, the changes of the ultrastructure of intestinal mucosal epithelial cells may be associated with the pathogenesis of PI-IBS. To date, there are no successful treatments for PI-IBS, and management of PI-IBS primarily aims at relieving the symptoms.
Natural medicine is generally considered safe and with few adverse drug reactions. As a representative natural medicine, traditional Chinese medicine (TCM) is more and more widely used nowadays. HXZQ oral liquid is a Chinese patent medicine composed of 10 kinds of Chinese medical medicines. It was modified based on a traditional formula named Huoxiang Zhengqi powder, which originated from the ancient Chinese pharmacy book "Formularies of the Bureau of the People's Welfare Pharmacies" (Tai ping Huimin Hejiju Fang) in the Song Dynasty of China; it has been mainly used to treat gastrointestinal diseases for more than 1000 years.