The drug discovery and development process is a very lengthy and complex endeavor. This process may take 10-15 years and require a billion dollars in investment. Not to mention, only a few drugs out of thousands of potential leads reach the approval phase. Hence, sponsors continuously focus on utilizing robust techniques such as multiplex cytokine assays and multiplex ELISA assays for reliable results. Besides, emphasizing LC-MS validation and custom Luminex assays further enables the inclusion of the latest technologies. The current article highlights the four critical phases of drug development.
Four phases of drug development
The drug discovery and development process is divided into four fundamental stages: Drug discovery phase, preclinical studies, clinical trials, and regulatory approval. Let’s dive deep and explore each of these stages in detail.
Drug discovery phase
The primary aim of the drug discovery phase is to identify and optimize potential drug candidates. Ideally, these lead candidates must elicit a desirable response against the disease target. The discovery stage involves assessing potential leads through several laboratory assessments, including biochemical assays, in-silico platforms, animal models, and cell cultures. The workflow of drug discovery studies is as follows:
- Target identification
- High Throughput screening
- Assay development
- Lead generation
- In-vivo and in-vitro assays.
In the preclinical stage, the drug candidates passing the initial phase are extensively refined and optimized through animal or other alternative models. The ultimate objective of preclinical studies is to generate sufficient evidence for the safety and efficacy of the drug candidate. These safety and efficacy data are crucial for clinical trials. Only after the US FDA is convinced that the drug is safe and effective for the intended population sponsors can test the drugs on human participants.
Clinical trials consist of 4 phases: Phases I, II, III, and IV. In phase I studies, scientists test the safety and tolerance of the drug candidate in a small pool of healthy participants. Usually, Phase I studies have around 20 to 80 healthy subjects.
Researchers aim to assess safety, efficacy, and tolerance in a larger patient population in the second phase,. In Phase IIa studies, the proof of concept is assessed. While in phase IIb studies, scientists focus on identifying the correct dose. Ideally, this phase consists of 100 to 500 target patients.
In the third phase of clinical trials, scientists test the drug on thousands of target patients. Depending on the data received, the US FDA may approve or disapprove the drug.
Post-completion of clinical studies, sponsors submit their data for review. For a drug product to be marketed to the patient population, the drug must be approved by the concerned regulatory authorities. However, from thousands of early drug candidates, only a few reach the approval stage.
Phase IV studies, also called Post-Marketing surveillance, are performed after the drug product receives market authorization from the US FDA. Such surveillance ensures that any adverse events are monitored and avoided. During this phase, sponsors conduct more comprehensive data regarding the safety and efficacy of the drug product.