A double-blind, randomized, placebo-controlled trial studying the effects of Saccharomyces boulardii on the gastrointestinal tolerability, safety, and pharmacokinetics of miglustat

BACKGROUND Gastrointestinal (GI) disturbances such as diarrhea and flatulence are the most frequent adverse effects associated with miglustat therapy in type 1 Gaucher disease (GD1) and Niemann-Pick disease type C (NP-C), and the most common recorded reason for stopping treatment during clinical trials and in clinical practice settings. Miglustat-related GI disturbances are thought to arise from the inhibition of intestinal disaccharidases, mainly sucrase isomaltase. We report the effects of a co-administered dietary probiotic, S. boulardii, on the GI tolerability of miglustat in healthy adult subjects. METHODS In a double-blind, placebo-controlled, two-period, two-treatment cross-over trial, healthy adult male and female subjects were randomly allocated to treatment sequences, A-B and B-A (treatment A - miglustat 100 mg t.i.d. + placebo; treatment B - miglustat 100 mg t.i.d. + S. boulardii [500 mg, b.i.d.]). GI tolerability data were collected in patient diaries. The primary endpoint was the total number of 'diarrhea days' (≥3 loose stools within a 24-h period meeting Bristol Stool Scores [BSS] 6-7) based on WHO criteria. Secondary endpoints comprised numerous other diarrhea and GI tolerability indices. RESULTS Twenty-one subjects received randomized therapy in each treatment sequence (total N = 42), and overall, 37 (88 %) subjects completed the study. The total number of diarrhea days was <1.5 for both treatment sequences, and approximately 60 % of subjects did not experience diarrhea during either treatment period. The mean (SD) number of diarrhea days was lower with miglustat + S. boulardii (0.8 [2.4] days) than with miglustat + placebo (1.3 [2.4] days), but the paired treatment difference was not statistically significant (-0.5 [2.4] days; p = 0.159). However, a significant treatment difference (-0.7 [1.9]; p < 0.05) was identified after post hoc exclusion of a clear outlier who had a very high number of diarrhea days (n = 13) and inconsistent GI tolerability reporting. The incidence of the GI AEs was higher with miglustat + placebo (82 %) than with miglustat + S. boulardii (73 %). There were no between-treatment differences in miglustat pharmacokinetics. CONCLUSIONS Although the primary endpoint was not met, the results of the post-hoc analysis suggest that co-administration of miglustat with S. boulardii might improve GI tolerability.