Its more likely the fda recognizes that very high number of people are on PPI's and prophylactic use in hospitalized patients still a common practice. 004 will regularly meet with ppi and cephalosporin abt combo prescribed to patients. Ppi's also increase risk of CDI, in some studies up to 65%. FDA started issuing warnings in 2013. Ppi's decrease gastric bactericidal activity by up to 50% and basically neutralize gastric juices that kill c-dif. Combine increased risk of ppi use with increased risk of cephalosporin abts and its easy to see why fda want this info. Syn-004 wont be much good to anyone if it cant function in concert with ppi's.
Increased gastric ph from ppi use likely not a concern. Much preclin done on 004 with human chyme. Wide Ph range tested, up to 6.8. Even that high, it degraded, maintained activity and stability for 6 hours. This was same for entire range. Given reliability of this type of chyme study, where they replicate exposure to hcl then to gastric secretions of varied duodenal environs (and much more), it would be highly unlikely if human trial results differed. The company studied human chyme/004 at ph much higher than ppi would cause.
Its in the duodenum that IV cefrtriaxone and other ceph abt's are released,coming in thru bile duct. This is important part of why SYN is so focused on 004 degredation in this area. It matters if it degrades in stomach. We want it to start breaking down in duod, activating as the abt is reaching duod thru ducts, both being pushed together via peristaltic waves to jejunum on. Intraintestinal longevity is really important. Those 6 hours are needed, and a breakdown in the high acid environ of the stomach would harm outcome. We'd basically have the old version, that couldn't stay active long enough to be viable.
Also, if you look at inclusion and exclusion of 004 studies so far, it looks very unlikely that a patient suffering from gastroparesis would be accepted.
