Drug Discovery

Drug discovery is the branch of science which deals with the design and discovery of drugs. The design of novel drugs is concerned with the various fields like medicine, pharmacology and biotechnology. In the earlier days, discovery of drugs was done by recognizing an ingredient in the traditional medicine. The drug discovery in those days was accidentally made. Today, the discovery of drugs was done by studying about the disease and the infection caused at a physiological and molecular level.

Drug discovery is a process which carries out primarily the recognition of candidates for the drugs, their synthesis, characterizing them, screening them and conducting in Vitro studies to learn about its efficacy. If the chemical compound has passed the tests in all these steps, it will go for developing into a future drug. This drug that is developed will be later used for clinical trials.

There are major breakthroughs that have occurred in the recent past regarding the improvement in the technology used for drug discovery. Though the technology supports this process effectively now, the drug discovery was observed as an expensive, lengthy and inefficient process. The research done for the purpose of the discovery of a new chemical entity spent around US$1.8 billion.

For the drug discovery to go smoothly, it is necessary to know about the various drug targets or disease causing defective proteins. To understand about the targets properly in every disease, it would be convenient if the entire knowledge about the human genome is exposed. As the project on human genome has revealed about every gene and its encoding details, it has become easy for the scientists to remove the barriers in identifying the therapeutic targets. Difficulty in identification of targets has been a problem since some time for initiating the drug discovery process. Human genome project has diminished that limitation.

There are new targets and established targets. Choosing new targets might be difficult for the drug discovery cycle as they do not have the known history and pathway in the biochemical aspect. The genes involved in their synthesis will not be clear. In the case of established targets, it is easy for designing the drug based on it, as the target is already established with enough information.

The designing of drugs can be done by In-Silico methods which take very less time for generation of lead molecule. The lead molecule that is designed can be sent later to the synthesis and it can be tested for its target inhibiting ability. This will prove the ability of the drug to even restrict the disease. The lead molecule can be used for screening purpose by using a technique called "High-throughput screening" or popularly called as HTS.

In this process of HTS, the various chemicals which are similar to the designed lead molecule can be used for matching with the inhibiting properties against the desired target. This is done by using them in in-vitro studies. The chemicals which are found to be having target inhibition properties will be screened. This compound can be made to undergo pharmacophore and structure-activity relationship studies.

If the compound shows enhanced activity against the desired target, decreased activity against the unrelated target, and possess ADME properties it can be selected for further tests. The quality of the compound can be tested using Lipinski's rule of five. Apart from high-throughput screening virtual throughput screening is also done to bring the leads very fast into the picture. Lead generation is also done using combinatorial chemistry. For this procedure many of the natural products from the plants and animals can be used for development of drugs against bacterial infections. Ultimately the discovered drug will be synthesized and sent for clinical trials to be released into the market successfully.