Clinical trial designs of new medicinal products for treating schizophrenia: discussion of EMA's Guideline and a Better Long Term Trial Design

Background and Objectives: Schizophrenia is a severe chronic disease. Endpoint variables lack objectivity and the diagnostic criteria have evolved with time. In order to guide the development of new drugs, European Medicines Agency (EMA) issued a guideline on the clinical investigation of medicinal products for the treatment of schizophrenia. Methods: Authors reviewed and discussed the efficacy trial part of the Guideline. Results: The Guideline divides clinical efficacy trials into short-term trials and long-term trials. The short-term three-arm trial is recommended to replace the short-term two-arm active-controlled non-inferiority trial because the latter has sensitivity issues. The Guideline ultimately makes that three-arm trial a superiority trial. The Guideline discusses four types of long-term trial designs. The randomized withdrawal trial design has some disadvantages. Long-term two-arm active-controlled non-inferiority trial is not recommended due to the sensitivity issue. Extension of the short-term trial is only suitable for extension of the short-term two-arm active-controlled superiority trial. The Guideline suggests that a hybrid design of a randomized withdrawal trial incorporated into a long-term parallel trial might be optimal. However, such a design has some disadvantages and might be too complex to be carried out. Authors suggest instead a three-group long-term trial design, which could provide comparison between test drug and active comparator along with comparison between the test drug and placebo. This alternative could arguably be much easier to carry out compared with the hybrid design. Conclusions: The three-group long-term design merits further discussion and evaluation.

Informed consent in clinical research: do patients understand what they have signed?

Informed consent is an essential element of research, and signing this document is required to conduct most clinical trials. Its aim is to inform patients what their participation in the study will involve. However, increasingly, their complexity and length are making them difficult to understand, which might lead patients to give their authorization without having read them previously or without having understood what is stated. In this sense, the Ethics Committees for Clinical Research, and Pharmacists specialized in Hospital Pharmacy and Primary Care in their capacity as members of said committees, play an important and difficult role in defending the rights of patients. These Committees will review thoroughly these documents to guarantee that all legal requirements have been met and, at the same time, that they are easy to understand by the potential participants in a clinical trial.