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Drug discovery is the search for the next breakthrough medicine that will ultimately improve a patient’s quality of life. Early drug discovery in particular, is an exciting but complex journey, requiring thousands or even millions of compounds to be screened in the hope of finding that needle in a haystack.

But, to have any chance of finding this all-important medicine, the bioassays you use to assess the activity or potency of your compounds needs to be designed with care. Below we share some of the key principles of bioassay design that can help you construct the best bioassay for your needs.

Two important approaches to early drug discovery

Whether you’re developing a bioassay to test five, five thousand, or five million compounds or biologics, you want to be certain that you’re getting reliable results every time. This means your bioassay must be both consistent and reproducible to ensure you are testing each compound with the same degree of scientific rigour.

Two of the most relevant approaches are:

1. Target-based drug discovery (TDD): requires knowledge and understanding of the target and its mechanism of action in the disease
2. Phenotype-based drug discovery (PDD): takes a holistic approach to examining the outcome of a complex biological system when influenced by compounds or biologics


We provide context to help you choose which of these approaches is best for your research in our free eBook, where we also reveal the key questions you must address along your journey to drug discovery success.

What are the key principles for designing successful bioassays?

Now that you have decided on the best approach to your bioassay design, the next step is to consider some key questions about its suitability to assessing your target, as well as its practical application:

1. How does the compound interact with the target? How will this affect the disease mechanism? It is essential to understand what is going on at the molecular level, so you can decide how to measure the compound’s effect
2. What does the literature say about your target and bioassay type? There’s no point in re-inventing the wheel! Detailed reviews of the known types of bioassays are available and can help you choose which one is most suitable to your target type
3. Have you defined what type of biological response your assay will detect? Inhibitory (antagonist), stimulatory (agonist) or modulatory responses will each require different bioassays
4. Are all reagents required for your bioassay commercially available, or will you need to make some (or all) inhouse? Consider the amount you will need for the lifetime of the project and the time and cost involved in producing your own reagents
5. Do you have access to a pharmacological tool compound or standard? This will enable you to develop your bioassay within a defined activity range

What are the next stages in bioassay development?

So far, we’ve answered some big questions in bioassay design and development, which will take you a long way along the path to success. But injecting these key principles into your future bioassays is only one step on this complex journey – there are many more considerations to take into account. For example, are your reagents stable in the context of your bioassay development? And what plate types and formats will best suit your bioassay requirements?

We delve into all of these considerations and more in our free eBook. Here you can read about the technical and practical considerations that are essential to build effective bioassays, helping you build the best bioassay for your needs.