COMBINATORIAL CHEMISTRY: A QUANTITATIVE IMPULSE IN THE INVESTIGATION OF NEW DRUGS The Institut Univ. de Ciència i Tecnologia has a program on Combinatorial Chemistry as a key tool to development new drugs. The effectiveness of the combinatorial synthesis with the development of new techniques of screening for a great number of samples (HTS, High Throughput Screening) allows to accelerate the process of the Drug Discovery and revolutionizes the investigation of new pharmaceutical active principles. IUCT has a group of dedicated investigators to explore synthetic combinatorial routes in the pharmaceutical field and which offers a service of R+D to the pharmaceutical companies. In addition, each year organizes a course of 30 hours of duration with the participation of national and international experts in the field of combinatorial chemistry. The process to find substances with some type of diverse biological activity has been one of the most important pharmacy approaches. Originally, the research of active principles was made in products coming from plants, animals, microorganisms… Later, the classic organic synthesis was added as a very powerful tool to develop new drugs or to improve the activity of those coming from natural products. In the 80's, new molecular biology knowledge allowed to relate the chemical structure of the compounds with their biological activity and therefore they provided a theoretical base for the active compound synthesis. In the last decade of the 20th century, combinatorial chemistry has used to develop new syntheses strategies. What contributes to combinatorial chemistry to the process of the Drug Discovery? Mainly, effectiveness. Combinatorial Chemistry allows to obtain hundreds, thousand and even million of products in comparison with the investigation with natural products or the classic organic synthesis that lead to obtain only a few . All these compounds, known as chemical libraries, must be evaluated from the point of view of their biological activity (ej: if it has been tried to develop a antimicrobial drug , we need to evaluate his effectiveness with the microorganism). The parallel development of automatic techniques of screening (HTS, High Throughput Screening), that allows to evaluate the biological activity of a great number of samples, has supposed a great impulse for the combinatorial synthesis of drugs. However, with the combination of the combinatorial synthesis and techniques HTS, can be synthesized hundreds of compounds in few stages and then to evaluate their biological activity very quickly. The number of potential drugs to evaluate in tests in vitro and clinical trials grows exponentially.