Drug food interactions can have a significant impact on the safety and efficacy of orally administered drug products. These effects can manifest in different ways.


  • In some cases, co-administration of an orally administered drug with food can increase the systemic exposure of the drug, potentially leading to an increased pharmacologic effect impacting efficacy and/or safety findings. 
  • In other cases, administration of an orally administered drug with food can lower the systemic absorption of a drug, thereby reducing the efficacy.

Hence, assessing the effect of food on the absorption of an orally administered drug contributes to the optimization of the safety and efficacy of the product and helps provide adequate instructions for drug administration in relation to food. Because diets vary with respect to the amount and type of food, and maintaining strict control over the daily content of food can be difficult, developing drug formulations that are not affected by food is strongly encouraged.

However, when developing such formulations is not possible, well-conducted food effect (FE) studies can inform how, when, and why drugs should or should not be administered with food. 

During new drug development, pharmacokinetic studies to assess the effect of food on the systemic exposure of the drug are conducted to determine: 

(1) if, and to what extent, food impacts the systemic exposure of the drug; 

(2) whether food changes the variability of the systemic exposure of the drug; 

(3) if the effect of food is different across meals with different fat or caloric contents.

Understanding the exposure-response relationships of the drug can be informative in assessing the implications of FE studies. 

Additionally, the impact of various clinical dosing scenarios is important to provide adequate instructions for use of the drug. In some cases, the clinical pharmacology characteristics of the drug could suggest that it should be administered only under fasted conditions.

This guidance provides recommendations to sponsors planning to conduct food-effect (FE) studies for orally administered drug products under investigational new drug applications (INDs) to support new drug applications (NDAs) and supplements to these applications for drugs being developed under section 505 of the Federal Food, Drug, and Cosmetic Act (21 U.S.C. 355). 


FDA Guideline | Assessing the Effects of Food on Drugs in INDs and NDAs – Clinical Pharmacology Considerations