The status of Investigational New Drug (IND) is required by the U.S. Food and Drug Administration (FDA) before clinical studies may be conducted and a new drug can be approved for the market. To acquire the status of IND, researchers must submit an IND application to the FDA with information in several key areas. A core piece of the information required by the FDA in the IND application is pharmacokinetic and toxicology data. The nonclinical studies that are run to acquire the pharmacokinetics and toxicology data requested by the FDA for the IND application are known as IND enabling studies.

In the preclinical phase of drug development one of the sponsor's primary goals, in addition to developing a new chemical entity (NCE) with therapeutic benefits warenting commercialization, is to determine if the NCE is reasonably safe to enter human clinical trials. If an NCE displays no favorable therapeutic benefits then there is no reason to continue preclinical development of the specific NCE. However, if the NCE displays favorable therapeutic benefits, but shows data that the drug candidate might not be safe for human use, this is cause for concern. In the event of unfavorable safety data being submitted in an IND application to the FDA, the drug candidate would likely not be granted the status of Investigational New Drug.

Why Are IND Enabling Studies Needed?

Pharmacokinetics and toxicology data acquired from IND enabling studies are designed to show that the proposed Investigational New Drug will be relatively safe for humans in clinical trials. Without the data from running IND enabling studies the FDA would have no way to evaluate if an NCE is safe enough to enter the clinic.

Pharmacokinetics
IND enabling PK assessments commonly include a set of studies referred to as ADME studies. ADME stands for Absorption, Distribution, Metabolism, and excretion or elimination. These ADME studies look at how a drug moves through the body and can be done in vitro (with cell or tissue-based models) or in vivo (In animals).

Toxicology:
The IND enabling toxicology assessments, for the most part, are toxicity studies directed in two mammalian species. Very frequently toxicology studies for the IND application are run in vivo, however, in vitro data is also frequently submitted to further characterize the safety of the Investigational New Drug candidate.

Conclusions
IND enabling studies are run to obtain key data on NCEs based on recommendations by the United States FDA. This key data falls into the two categories of pharmacokinetic data and toxicology data. This data is designed to show an IND candidate is relatively safe to begin human clinical trials. The IND enabling studies can be done with a variety of in vitro or in vivo methods and often a combination of both is used. Once an IND application is approved, very frequently the drug candidate progresses to human clinical trials.