Drug discovery is the process by which new candidate medications are discovered in fields of medicine and pharmacology. Drugs were discovered by identifying the active ingredient from traditional remedies or by serendipitous discovery as with pencillin. More recently, chemical libraries of synthetic small molecules, natural products or extracts were screened in intact cells or whole organisms to identify substances that had a desirable therapeutic effect in a process known as classical pharmacology. After sequencing of the human genome allowed rapid cloning and synthesis of large quantities of purified proteins, it has become common practice to use high throughput screening of large compound libraries against isolated biological targets which are hypothesized to be disease-modifying in a process known as reverse pharmacology. Hits from these screens are then tested in cells and then in animals for efficacy. Phases of Drug Discovery and Development There are five critical steps in the U.S. drug development process, including many phases and stages within each of them. The five steps include-

1. Discovery and Development

2. Preclinical Research

3. Clinical Development

4. FDA Review

1. Discovery and Development

The first step in drug development is drug discovery. When new insights and technologies become available, discovery is possible to find new treatments for diseases.

This can begin with thousands of different compounds to start with, which will be narrowed down over time. Once the most promising compounds are determined, the development phase can begin. During development, many details need to be taken into consideration. This includes learning more about what the dosage amount of a drug should be, how effective it is, and potential side-effects, to name a few. Today drug discovery involves screening hits, medicinal chemistry, and optimization of hits to reduce potential drug side effects (increasing affinity and selectivity), efficacy or potency, metabolic stability (half-life), and oral bioavailability are also improved in this step of drug development process. The drug discovery process ends one lead compound is found for a drug candidate, and the process of drug development starts.

2. Pre-Clinical Research

Once a lead compound is found, drug development begins with preclinical research to determine the efficacy and safety of the drug. Preclinical trials test the new drug on non-human subjects for efficacy, toxicity, and pharmacokinetic information. These trials are conducted by scientists in vitro and in vivo with unrestricted dosages. Researchers determine the following characteristics of the drug- • Absorption, distribution, metabolization, and excretion information • Potential benefits and mechanisms of action • Best dosage, and administration route • Side effects or adverse events • Effect on gender, race, or ethnicity groups • Interaction with other treatments • Effectiveness compared to similar drugs

3.Clinical Research

Once preclinical research is complete, researchers move on to clinical drug development including clinical trials and volunteer studies to fine tune the drug for human use.

Phase 1 study includes healthy volunteer study, where the drug is tested on humans. Less than 100 volunteers will help researchers to assess the safety and pharmacokinetics, absorption, metabolic, and elimination effects on the body, as well as any side effects for safe dosage forms.

Phase 2 and phase 3 studies include studies in patient population where the standard drug previously used as treatment or placebo is tested on 100-500 patients. Analysis of optimal dose strength helps create schedules while adverse events and risks are recorded.

Phase 3 involves 1000-1500 patients enabling medication labeling and instructions for proper drug use. This phase requires collaboration, organization, IEC or IRB coordination and regulation in anticipation of full scale production following drug approval.

4. FDA Review

After preclinical and clinical research has shown that a drug is both safe and effective, the developer can submit their research to the FDA. Of course, getting FDA approval of a new drug is key to getting it on the market, so the FDA review is an integral part of developing a drug. To have their medication reviewed, a developer needs to submit a New Drug Application that provides detailed information about their medicine. This application includes all of the developer’s findings from the prior stages. The FDA has six to 10 months to complete the review. Before approving a new drug, the FDA may have additional questions or require more studies. 

Even after the FDA approves a drug, they continue to monitor its safety. To ensure that the drug is safe on the market, they watch over how the drug is being advertised and if any issues arise. Should problems come up with a drug, the FDA can step in.