[Therapeutic uses of investigational drugs: research extension, compassionate use, and expanded access].

This article describes the methodological, regulatory, and ethical aspects of the different therapeutic uses of investigational drugs--research extension, compassionate use, and expanded access. Worldwide, the principle challenges of this kind of treatment are: setting minimum quality standards for researchers, as well as institutions, so that projects can include drugs at various stages of development; training of evaluation and assessment committees on the methodological, regulatory, and ethical aspects of new drug research; clearly outlining the relationship between researchers and funding organizations and between researchers and study participants; and understanding the opposition to the recent proposal to enable drug manufacturers to charge for drugs used in research studies.