We are developing a proprietary class of “dual” absorption enhancers that inhibit both the P-gp transporter and the CYP enzymes within the gastrointestinal tract. There are many barriers that limit the oral absorption of drugs in humans. The P-gp transporter is a major barrier to absorption of active chemotherapy drugs. However, certain other drugs with P-gp liabilities may also have liabilities for other barriers such as metabolizing enzymes, primarily the cytochrome P450, or CYP, class of enzymes. These CYPs limit oral absorption of certain drugs by metabolizing drugs within the gastrointestinal tract before they can be absorbed. This class of dual absorption enhancers has shown potential to significantly improve the oral bioavailability of certain other drugs in laboratory tests, and may expand the application of our oral absorption platform to drugs where the CYP barrier to oral absorption is also important. These dual absorption enhancers may lead to better performing next- generation oral medicines in our pipeline of clinical products.
The development of these dual absorption enhancers is at the preclinical stage. Proof of concept, providing increased oral bioavailability in preclinical species, has been obtained with several absorption enhancers and candidate drugs. Currently additional filters such as patentability/freedom to operate, physical-chemical characterization, pre-formulation studies, manufacturing analysis and preliminary toxicity testing are being applied to our first group of lead candidates for clinical development.