Clinical trials design: protocols and endpoints

Over the last decade there has been a proliferation in clinical trials to test agents for the treatment of erectile dysfunction (ED). Many aspects of clinical trials design and conduct and guidelines for future conduct have been the subject of a recent comprehensive review (Rosen R et al. In: Proceedings of the 1st International Consultation on Erectile Dysfunction 1999). The present article attempts to extend that analysis from trials that focus purely on symptomatic improvement of ED to trials relevant to the management of the ED patient in the community. Although the regulatory approval process accounts for the bulk of the clinical trials undertaken, studies are also initiated for concept testing, post-marketing surveillance and for promotional and/or pricing reasons. The trial design can be dependent on which of the above objectives is being served. However, there are also many common features that are summarized below; the major focus is placed on regulatory-standard or ‘pivotal’ studies.