Results from two Phase II trials of partial GABA-A selective receptor agonists indicate that subtle differences in receptor selectivity can have significant clinical effects.

Neurogen Corp.'s NGD91-3 small molecule GABA-A partial agonist did not meet its primary endpoint of reduction in the physician-reported HAM-A anxiety score in patients with generalized anxiety disorder (GAD). But Interneuron Pharmaceuticals Inc. reported results of a similar 6-week study in GAD patients in which its pagoclone GABA-A partial agonist did provide significant reductions in HAM-A score from baseline compared to placebo (see B13).