The preclinical stage includes the discovery and optimization of lead compounds, the establishment of targets and models. Both can be used as the starting point for drug development: 1. Lead compounds are obtained through screening models, the lead compounds are optimized, and then the model is used for evaluation; 2. Medicinal chemistry can also be optimized from the lead compounds for design and synthesis. After the target product is evaluated with a model.
The model here is not just a cell model, but also an animal model (not including humans). The evaluation indicators are not only pharmacodynamics, but also pharmacokinetics, safety, etc. The shortcomings obtained after evaluation can become The goal of optimization (pharmaceutics can also be seen as an optimization method). In short, the pre-clinical work is carried out with continuous cooperation in these aspects until a drug that is effective and safe on mammals is obtained. At this time, all the information is sorted out and an application is submitted to the FDA. After approval, you can enter the clinic. Phase of the experiment.
The clinical phase is mainly divided into phases I, II, and III: 20~80 healthy people are selected for the phase I experiment, and the safe dose range of the test drug, pharmacokinetic data; the phase II experiment selects 100~300 patients to participate, right The efficacy of the drug was evaluated, and the famous Chongqing hepatitis B vaccine fell down here; the phase III experiment requires the participation of 1,000 to 3,000 patients to evaluate the efficacy, toxic and side effects and other indicators.
Well, if all of these are passed, you can take out more than 100,000 or 200,000 pages of drug declaration materials and submit it to the FDA for review. If the FDA passes, the drug can be marketed, but it is not over yet, and the drug needs to be IV. Phase clinical, further evaluation.
As everyone has said, the development of a drug takes an average of 12 years, including about 3.5 years in the preclinical phase, 1, 2, and 3 years for phase I, II, and III clinical trials, and 2.5 years for follow-up approval. If 5,000 compounds enter preclinical trials, only 5 of them can enter the clinical stage, and at most 1 can be marketed. The cost of drug research increases rapidly with the deepening of the research phase. Usually, the cost of a new drug research and development is about 5 billion US dollars.