What is in FeSSIF?

In response to eating a meal, the upper intestines secrete surfactants (bile salt and phospholipid) to help break the food down. FeSSIF (Fed State Simulated Intestinal Fluid) contains the same types and levels of these surfactants. These are critical, particularly for poorly water-soluble drugs, because they form mixed micelles which can enhance drug solubility and dissolution greatly. This in turn can have a significant effect on how the drug is absorbed. It’s one of the reasons why absorption of lipophilic poorly-soluble drugs is often influenced by food.

FeSSIF has the average pH of fed intestinal fluid and similar osmolarity too. These are important parameters to control when testing drugs or formulations sensitive to pH and salt content. The exact composition of FeSSIF is provided here:

You can make FeSSIF in an instant with our FaSSIF/FeSSIF/FaSSGF powder available here.