Phytotherapy for functional dyspepsia: a review of the clinical evidence for the herbal preparation STW 5.

Functional gastrointestinal disorders such as functional (or non-ulcer) dyspepsia are characterized by a broad spectrum of symptoms referred to the upper abdomen without a detectable cause utilizing routine diagnostic measures. It is now believed that disordered gut function (including abnormalities like disturbances of motility such as postprandial fundic relaxation, gastric emptying and disturbed visceral sensory function) play a key role for the manifestation of these disorders. The underlying pathophysiology is not yet fully understood. However, the available data suggest that a number of factors may contribute to the manifestation of symptoms. These factors include environmental factors such as acute infections as trigger event, psychological stressors that may precede acute exacerbations and a genetic predisposition. Considering the large number of mechanisms, a treatment targeting a single mechanism is unlikely to be effective in all patients. Indeed, chemically defined treatments usually gain a 10-15% superiority over placebo. In recent years placebo-controlled studies have demonstrated superiority of a commercial multicomponent herbal preparation, STW 5, with the trade name Iberogast, for the treatment of patients with functional dyspepsia and irritable bowel syndrome. This phytopharmacon is a combination of nine plant extracts each with a number of different active constituents. Pharmacological studies have shown different effects of the single plant extracts on the (molecular) mechanisms which are discussed as underlying the manifestation of symptoms. Various well-controlled clinical trials have independently confirmed clinical efficacy and safety. The clinically efficacy of this multicomponent herbal preparation questions the current trend of highly targeted drug molecules that usually target one single receptor population while it has not been shown that a single receptor group plays a pivotal role for the control of symptoms. Herbal medicines are obtained from various plants and contain complex extracts with a large number of different active substances. While there are only limited head-to-head comparisons with conventional chemically defined medications, the combination of extracts with various gastrointestinal active ingredients appears to be advantageous for a heterogeneous condition such as functional dyspepsia.