Predicting Food Effects in Oral Drug Absorption with Biorelevant Dissolution–Permeation Testing
A promising oral formulation can perform perfectly in standard dissolution tests—only to fail in clinical trials when it’s taken with food. Unexpected “food effects” like the one described remain one of the most common and costly challenges in oral drug development, often emerging late when changes are expensive and timelines are tight.
For orally administered drugs, the food effect describes how food influences drug absorption. The impact may be positive (enhanced absorption), negative (reduced absorption), or neutral. Understanding these effects during formulation development is critical, as negative food effects may require formulation adjustments or specific dosing recommendations.
Despite their importance, food effects are often not evaluated until clinical studies since conventional in vitro dissolution testing does not reliably predict in vivo absorption. In some cases, increased solubility in fed-state media leads to improved absorption and a positive food effect. In others, drug molecules remain solubilized in micellar structures formed by bile salts and lipids, limiting the free drug concentration available to permeate through the intestinal membrane. When this occurs, apparent improvements in dissolution do not translate to improved absorption and formulators may over- or under-predict the food effect, leading to suboptimal excipient selection, unnecessary reformulation, and the potential for late-stage failures.
This is where combined dissolution–permeation testing offers a meaningful advantage. The application note “Improved Prediction of Food Effect on Oral Drug Absorption” describes how the MicroFLUX and MacroFLUX dissolution-permeation systems are used to predict food effects earlier and with more accuracy than when measuring dissolution alone. By measuring dissolution and permeation simultaneously across a lipid-coated artificial membrane, the systems provide a mechanistic approach that enables a more biorelevant assessment of absorption behavior.
Small-volume studies with MicroFLUX showed that increased dissolution in fed-state media did not always translate to increased absorption, indicating that free drug concentration remained similar under fed and fasted conditions. Without permeation measurements, this increased insolubility could have been misinterpreted as a positive food effect.
Larger-scale testing with MacroFLUX further demonstrated improved predictability, enabling the correct identification of positive versus negative food effects for nine of ten compounds – compared to only five when using dissolution data alone. Notably, standard dissolution testing failed to reveal any negative food effects.
Together, these findings highlight the importance of evaluating both dissolution and permeation together when assessing food effects and underscore the value of incorporating biorelevant testing earlier in oral formulation development. Doing so ultimately helps to reduce the risk of late-stage surprises, improve confidence in formulation strategies, and support the development of oral drug products with more predictable clinical performance.
Download the application note, Improved Prediction of Food Effect on Oral Drug Absorption, for detailed methodology and complete study results.
