Open-label extensions of placebo-controlled randomized clinical trials are commonly conducted. At the end of the placebo-controlled period, all patients have their intervention stopped and are re-titrated to optimal therapeutic levels of the active agent. In this month's issue of the Archives of Neurology, Reisberg and colleagues publish their 24-week open-label extension study of memantine in moderate to severe Alzheimer disease (AD).1 Publication of this extension study raises the question of what we learn from such investigations. Three types of questions arise: (1) What can we learn about memantine? (2) What can we learn about clinical trials? (3) What can we learn about drug development for AD?
Cummings JL. What We Can Learn From Open-Label Extensions of Randomized Clinical Trials. Arch Neurol. 2006;63(1):18-19. doi:10.1001/archneur.63.1.18