The herbal preparation STW5 (Iberogast®) has potent and region-specific effects on gastric motility

Functional dyspepsia (FD) is amongst the most common functional gastrointestinal disorders. Symptomatic treatment includes the use of herbal preparations whose effects on gastric motility are unclear. The present study aimed at investigating the effects of STW 5 (Iberogast®), a fixed combination of hydroethanolic herbal extracts, on gastric motility in vitro. Muscle strips from guinea-pig gastric fundus, corpus and antrum were set up in organ baths either in circular or longitudinal orientation. Addition of ethanol-free STW 5 to the organ baths (32-512 μg mL^-1) dose-dependently evoked a sustained and reversible relaxation of circular and longitudinal fundus and corpus muscle strips without changes in phasic activity. In contrast, antral muscle strips responded to STW 5 with a significant increase in the contractile force of phasic contractions without changes in tone. All effects were resistant to tetrodotoxin (0.5 μmol L^-1), atropine (1 μmol L^-1), ω-conotoxin GVIA (0.5 μmol L ^-1), capsaicin (1 μmol L^-1) or L-NAME (100 μmol L^-1), suggesting that neither nerves nor nitric oxide pathways were involved. These data demonstrate that STW 5 profoundly alters gastric motility in a region-specific but not layer-specific manner and thus implicates Iberogast® in the treatment of FD patients suffering from motility disorders with impaired fundus accommodation and/or antral hypomotility.