GTS-21, also known as DMBX-A, is a derivative of the natural product anabaseine that acts as a partial agonist at neural nicotinic acetylcholine receptors. It binds to both the α4β2 and α7 subtypes, but activates only the α7 to any significant extent. Both GTS-21 itself and its demethylated active metabolite 4-OH-GTS-21 display nootropic and neuroprotective effects, and GTS-21 is being investigated for the treatment of Alzheimer's disease, nicotine dependence, and, most significantly, for schizophrenia.

GTS-21 showed statistically significant enhancement of three measures of cognitive function (attention, working memory, episodic secondary memory) compared to placebo.