The major issue is that we don't really have the licensing framework for a living thing. The "drug" keeps changing. The neat part of phage is that they co-evol

The major issue is that we don't really have the licensing framework for a living thing. The "drug" keeps changing. The neat part of phage is that they co-evolve along with the bacteria they're feeding on, but it means there's no really consistent formulation. It's unique, and it's not fixed. The same problem effects fecal transplant. "The healthy gut flora of a donor" is much harder to approve and regulate than "Famotidine 10mg, Calcium carbonate 800 mg, Magnesium hydroxide 165mg" (the antacids on my desk).