ABSTRACT
The first one or two clinical trials evaluating the efficacy of a novel drug have a direct effect on the future of that drug, and sometimes the future of that class of drugs. Following phases Ia, Ib, and IIa studies, a critical decision must be made: to pursue or not to pursue further clinical development. When treatment differences are found to be large, the concerns over trial design tend to melt away and decisions to proceed are relatively easy. However, results of trials with various classes of analgesics in neuropathic pain have thus far demonstrated that treatment differences are modest, at best (1). Therefore, design choices must be tailored to both the aims of the individual study, as well as to the longer-range goals of drug development. For example, duplicate treatment versus placebo studies, with no regard for dose-effect, would be of little use in guiding the future direction.
