Santarus announced that its Phase 3 clinical study to evaluate the safety and efficacy of the investigational drug, rifamycin SV MMX, met the primary endpoint of reducing time to last unformed stool (TLUS) in patients with travelers’ diarrhea.

The Phase 3 clinical study enrolled 264 patients, 65 patients on placebo and 199 patients on rifamycin SV MMX, in an international multicenter, randomized, double-blind, placebo-controlled trial to assess the efficacy and safety of rifamycin SV MMX. The dosing regimen was 400mg (two oral tablets of 200mg each) taken twice daily (800mg total daily dose) of rifamycin SV MMX or placebo for three days in the treatment of patients with travelers’ diarrhea. The primary endpoint of TLUS was defined as the time (hours) between the administration of the first dose of study drug and the time that the last unformed stool was passed before the start of clinical cure. Clinical cure was defined in the study protocol as:

  • The passage of two or fewer soft stools and no watery stools, no fever (>100.4°F or 38°C), and no symptoms of enteric infection (other than mild excess gas/flatulence) during a 24-hour interval in the 120-hour data collection period after the first dose of study drug; or
  • The passage of no stools or only formed stools and no fever during a 48-hour interval in the 120-hour data collection period after the first dose of study drug, with or without other signs of symptoms of enteric infection.

In the intent-to-treat (ITT) population, the median TLUS was 46 hours for rifamycin SV MMX vs. 68 hours for placebo (P=0.0008). Results in the per protocol population (n=240) were similar to the ITT population.

Rifamycin SV acts by binding to the beta-subunit of bacterial DNA-dependent RNA polymerase resulting in inhibition of bacterial RNA synthesis. Rifamycin SV MMX utilizes proprietary MMX colonic delivery technology, which consists of a sequence of lipophilic and amphiphilic matrices dispersed within a hydrophilic matrix. MMX tablets are coated with gastro-resistant polymers that protect the active pharmaceutical ingredient (API) against degradation in the upper gastrointestinal tract and delay the release of the API until the tablet reaches the colon.

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