Pharmacology: Mechanism: Saccharomyces boulardii (S. boulardii) appears to be taken up by the intestinal villi and to adhere to cells in the jejunum, increasing brush border enzyme activity of lactase, alpha-glucosid normal enterocyte maturation. S. boulardii also exerts a protective effect on epithelial cells infected with E. coli by decreasing the level of intracellular infection & reducing the apoptotic effect of E. coli on intestinal epithelium.
S. boulardii has also been shown to increase intestinal secretory IgA production. In addition, prevents Entamoeba histolytica from adhering to human erythrocytes, a model of the first step in amoebic infection in humans. In C. difficile-related diarrhea and pseudomembranous colitis, Clostridium toxins bind to membrane receptors, causing intestinal fluid secretion and increased permeability of intestinal mucosa. S. boulardii contains a protease that neutralizes C. difficile toxins A and B, and also digests membrane receptors that bind to C. difficile toxin in the brush border epithelium of the ileum, thus exerting a protective effect on the gut lining.
Pharmacokinetics: Subsequent to oral administration and transport to the gastrointestinal tract. S. boulardii cells undergo irreversible degradation. In the large intestine, live cells are exposed to saccharolytic enzymes produced by the normal intestinal flora that hydrolyze polysaccharides in the cell wall. These same enzymes act to further degrade dead cells as well. Ultimately, S. boulardii appears in the bowel and feces. S. boulardii does not appear to colonize the intestinal tract, and a single oral dose is rapidly eliminated in the feces. When S.boulardii was monitored in stools of patients given a dose of 1 gram daily, only 1 % of the ingested dose was present and the organism was cleared completely from the stool within 3 days. In studies of patients taking ampicillin, S. boulardii recovery in the stool was increased 2.4 times, indicating when normal intestinal flora is altered, the level of S. boulardii in the intestine is elevated.