THE USE OF FREE SOFTWARES IN PRACTICAL CLASS ABOUT THE MOLECULAR FILTERS OF ORAL BIOAVAILABILITY OF DRUGS. The study of the physical chemical properties to predict the oral bioavailability of drugs is a widely tool used by researches on the Pharmaceutical and Medicinal Chemistry field. Even though it is a deeply studied subject, it is a complex task to teach to pharmacy students. Lipinski stablished that molecular weight, lipophilicity, hydrogen bond donors and acceptors are of great importance for oral bioavailability. In addition, Veber and Lovering added other properties, such as number of rotatable bonds, fraction of sp3 hybridized carbon and polar surface area that amplified the Lipinski Rule of 5. In this sense, the access to chemical databases and the comprehension of this information is an important task to undergraduate and graduate students. Thus, this work aims a new teaching methodology that values the critical interpretation of data and that favors the students comprehension beyond stablished rules.