Recovery and elimination of the biotherapeutic agent, Saccharomyces boulardii, in healthy human volunteers.

Saccharomyces boulardii (Sb) is a nonpathogenic yeast used to treat intestinal illnesses such as pseudomembranous colitis and antibiotic associated diarrhea. The behavior of this biotherapeutic agent in humans was determined (1) in investigating the effect of dose on the steady-state level and recovery and (2) in quantitating the effect of ampicillin on the recovery and elimination profile. As the Sb dose increased, the mean steady-state concentration of Sb increased significantly. The percentage recovery was dose independent. When a single Sb dose was administered 24 hr after beginning a course of ampicillin, there was a significant increase (P < 0.01) in both the area under the concentration versus time curve and the maximum fecal concentration compared to values obtained without ampicillin. Ampicillin increased steady-state recovery of the drug about twofold (P < 0.05) and steady-state levels about 2.4 times (P < 0.01). These studies have shown that there is a relationship between the dose and the amount of Sb recovered and that perturbation of the GI flora by ampicillin increases steady-state levels of Sb.