Background: The non absorbable antibiotic rifamycin SV newly formulated as modified colonic release MMX®
tablets was preliminarily investigated. Methods: In a multi-centre, double-blind, double-dummy, randomised, parallelgroup
study, efficacy and safety of the 200 mg tablets were investigated vs. rifaximin 200 mg tablets in infectious diarrhoea.
Results: 22 rifamycin SV recipients (47.8%) were successes, whilst 24 (52.5%) discontinued. In the reference
group 27 (50.9%) were successes, whilst 26 (49.1%) discontinued. The median time to last unformed stool was 67.5 h after
rifamycin SV and 65.5 h after rifaximin. Conclusions: The efficacy of the new tablets was not significantly different
from that of rifaximin administered 4 times a day for 3 days. The treatments did not differ in rate or frequency of therapeutic
success. Isolates of Campylobacter jejuni and lari, Escherichia coli, Anaerobiospirillum, Salmonella enteritidis and
Shigella flexneri found at pre-treatment were not retrievable after rifamycin SV.