Planta Med 2006; 72 - S_058
DOI: 10.1055/s-2006-949791

Pro-secretory effects in the human small and large intestine as a mechanism of action of STW 5 (Iberogast®) in irritable bowel syndrome (IBS)

O Kelber 3, D Krüger 1, F Zeller 2, SN Okpanyi 3, T Frieling 4, M Schemann 1
  • 1Human Biology, TU Munich, Hochfeldweg 2, 85350 Freising, Germany
  • 2Department Surgery, Clinic Freising, Mainburger Straße 29, 85356 Freising, Germany
  • 3Scientific Department, Steigerwald Arzneimittelwerk GmbH, Havelstr. 5, 64295 Darmstadt, Germany
  • 4Medical Clinic II, Clinic Krefeld, Lutherplatz 40, 47805 Krefeld, Germany

Phytotherapy is a successful approach to treat functional gastro-intestinal diseases. The indications of the fixed herbal combination STW 5, consisting of hydroethanolic extracts from Iberis amara, chamomile flower, peppermint leaves, caraway fruit, liquorice root, melissa leaves, angelica root, greater celandine herbs, and milk thistle fruit, include functional dyspepsia and irritable bowel syndrome (IBS). Clinical data show the efficacy in these indications [1–3].

We therefore investigated the effect of STW 5 on secretory activity of mucosa/submucosa preparations from human ileum and colon using the Using chamber technique. Experiments were performed on normal tissue from surgical specimens (59 preparations from 29 patients, age: 69.8±11.1), using an ethanol-free lyphilisate of the drug. Serosal application of STW 5 (256µg/mL-1024µg/mL) concentration dependently increased the short circuit current. Mucosal application had no effect. The response was similar in small and large intestine and the data were therefore pooled. The increase was 9.7±2.9µA/cm2 for 256µg/mL, 22±7.9µA/cm2 for 512µg/mL and 29±8.1µA/cm2 for 1024µg/mL (p<0.05 at all concentrations). The STW 5 evoked secretory effect was bumetanide (100µM) sensitive and therefore due to increased chloride secretion. Blockade of nerves by tetrodotoxin (1µM) and electrical field stimulation of nerves did not influence the effect, indicating a direct epithelial action of the drug.

Our results indicate that STW 5 has a significant pro-secretory effect in the human intestine in vitro. It does not interfere with neurally mediated secretion but appears to stimulate chloride secretion at the level of the epithelial cell. Decreased secretion is discussed as a relevant factor in the aetiology of IBS, in particular in its constipation-predominant form. So this mechanism of action may be of special relevance in the clinical effect of STW 5 (Iberogast®) in patients with IBS.

References: 1. Gundermann, K.J. et al. (2003), Advances in Therapy 20: 2–7. 2. Von Arnim, U. et al. (2004), Gut 53: A284. 3. Madisch, A. et al. (2004), Aliment. Pharmacol. Ther. 19: 271–279.