This February CDER issued draft guidance for clinical studies on the effects of food administration on and bioavailability of orally administered drug products. The bioavailability guidance also applies to drug products where systemic exposure measurements are appropriate for bioavailability measurements (such as drugs with transdermal delivery systems). Both guidance are intended for sponsors submitting data for INDs and NDAs of predominantly small-molecule therapeutics, since those are most likely to be orally administered. When issued, the bioavailability guidance will update a previous guidance document issued in 2014; the food effect guidance is brand new.

Bioavailability studies show how much of a drug dose is absorbed and reaches the site of action. This amount is affected by the amount dosed, the fraction of dose absorbed, and the effects of metabolic systems on the circulating drug. Food effect is a component of bioavailability, as the absorption of some drugs is affected by whether or not they are taken on an empty stomach. (Haven’t you always wondered why there are specific instructions on some prescriptions?)

Both guidance give detailed specifics on study design, execution, and data analysis, and cover special topics as appropriate. They are also open to comment; the food effect docket until 26APR2019 and the bioavailability docket until 26MAY2019. Both guidance are quite understandable by non-specialists, and I encourage you to check them out.

Text Copyright © 2019 Katrina Rogers