What Is The Need Of Assay Development And Validation For Drug Discovery?

An assay is an investigative procedure. It makes a qualitative assessment of a compound. What it effectively does is – to study the effect that a compound has on biochemical or cellular targets. In the drug development process, the initial steps are to pinpoint and validate those possible drug targets that are involved in human diseases. These drug targets can be enzymes, receptors, DNA, ion channels, and hormones and factors.

The next step is to create compound screening assays and biological assays. The job of these assays is to detect compounds that perform the desirable activity at the drug targets. Clinical scientists term these compounds as “hit molecules.”

The primary phase of identifying the hit molecules is also known as high throughput screening (HTS).  It’s an aggregation of compounds that contain several prospective hit molecules.  After the initial testing of the hit molecules, scientists deploy further assays to re-test the activities of the hit molecules at the target. Then the cell-based assays test the toxic component of a drug.  Testing is also conducted to check the drug’s safety and efficiency.

During the development process, the prospective drug goes through a series of specifically-designed and assays. These assays are also organized for the compound and drug target. This process goes by the name of assay development.

Assay Development – Critical Factors

The most essential aspect of drug discovery and development is to develop superior assays. The quality of the assays is inversely proportional to the chance of problems occurring later at the R & D stage. Several factors play an important role in assay development, like

Reproducibility – This should exist all across the assay plates and the entire duration of the drug development process.

Relevance – The assay should be able to forecast the state of the specific disease. Some compounds display suitable strength mechanisms. The assay must identify them as well.

Quality – The quality of an HTS assay is measured by the Z’ factor. For permissible usage, the Z’-factor needs to be more than 0.4.

Cost – The assay development cost needs to be within reasonable limits.

Types of Assays in Drug Discovery

There are two primary categories of assays in the drug discovery process – biochemical assays and cell-based assays.

Biochemical Assays

These assays are useful to identify and evaluate the target protein. They also help to ascertain the compounds that conduct the intended activity at the target. These assays are applicable to enzymes and receptor targets.

Cell-based assays

These assays help to identify the protein interactions, protein expressions, and localizations. Through these assays, scientists can determine how toxic and efficient the hit compound is.

Cell-based Assays – New Dimensions

The three-dimensional representation of gene profiles provides a much more authentic view compared to the traditional 2D cell culture. They can also imitate tumors in a better way that helps researchers perform a better drug screening process.

Assay Validation

Method validation is necessary to make sure that the assays are meeting the intended criteria for successful execution during the HTS activity. It acts as a confidence-building-measure on the assay and is also a parameter for more studies on it. The assay validation process also acts as a quality control yardstick.

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