Abstract : Any pharmacological treatment should ideally be effective and safe. The supervision of an ongoing therapy should control that individualized goals are reached while tolerance and safety are present. In case of not reaching the predefined objectives, the causes of failure should first be screened (for instance, exclusion of poor patient compliance), and the treatment should be then optimized : dose adjustment, add-on of another drug (if possible synergistic combination) and/or shift to a more effective pharmacological therapy. In some cases, therapeutic monitoring may be useful or even mandatory in order to better adjust drug dosing and thus guarantee both efficacy and safety.