Formulation patent applications rarely fail because the science is weak. They fail because the invention is not positioned to survive an obviousness analysis.
The formulation arts are congested. Whether the subject matter relates to emulsions, proteins, cosmetics or delivery technologies, there is almost always a substantial body of prior art nearby. As a result, patentability does not turn on whether your exact formulation exists. Instead, patentability turns on whether your formulation can be rationally inferred.
To sustain an obviousness rejection under 35 U.S.C. §103, the examiner typically points to (i) a similar base composition, (ii) a predictable reason to combine prior teachings, and (iii) a reasonable expectation that the combination would work.
