Drug is a chemical substance that alters body processes, which is used in medicine for the prevention, diagnosis and treatment of diseases (Farlex, 2011). Drug discovery is a long-term process that requires financial investment. The drug investigation process lasts approximately 9 to 15 years, during which the number of chemicals that can become drugs is reduced from 10,000 to 1-2 (Saparov, 2011). Even after production, the drug is studied by scientists to modify its structure, administration and effects on the body. Drug discovery consists of several stages that help examine its effectiveness and side effects. The pre-discovery process is the first phase of drug discovery. During the pre-discovery phase chemists and pharmacologists try to understand and identify factors that may play a significant role in the particular disease. After revealing the cause of the disease or understanding it, the target molecule against which the drug will act is chosen. To understand its structure, the target molecule is eliminated, isolated and its various interactions are investigated. Understanding the molecule's interactions can be helpful in finding the treatment for a specific disease. The next step involves demonstrating that the chosen molecule is relevant to the disease and proving that the drug target is associated with the desired change in the behavior of diseased cells (PPD, 2011). The second phase of the discovery process is the discovery of the drug itself. . Its main goal is to find a lead compound. The lead molecule is a promising compound that has the potential to become a drug. There are several ways to find the lead compound, including nature, de novo, high-throughput screening, and biotechnological methods. For many centuries drug......middle of paper......d time. It consists of pre-discovery and discovery, development, clinical trials and manufacturing processes. During each phase potential drugs are modified and side effects are reduced, even after production the drugs are monitored and patients' conditions are periodically reported to the FDA. An investment of money by a pharmaceutical company represents a huge risk as sometimes drugs are very dangerous. Therefore, they cannot be used and the process starts again.References1. Dr. Saparov, A. (2011). Drug discovery. Power point presentation.2. Pharmaceutical Research and Manufacturers of America. (2007). Drug discovery and development. Retrieved from: http://www.phrma.org/sites/default/files/159/rd_brochure_022307.pdf3. Campbell, N. A. and J. B. Reece, 8th edition. (2008). Biology. San Francisco: Pearson Benjamin Cummings.