Suronacrine (also known as HP128) is a tetrahydroacridinol derivative patented by Hoechst-Roussel Pharmaceuticals, Inc for the treatment of various memory dysfunctions characterized by decreased cholinergic function. The activity ofHP128 is attributable to its inhibition of both norepinephrine uptake and cholinesterase enzyme activity. Suronacrine has enhanced memory in animals with combined cholinergic and adrenergic lesions. In preclinical models, Suronacrine blocks responses to nerve stimulation and to carbachol, but increased responses to acetylcholine. Extracellular recording of nerve terminal currents from triangularis sterni preparations revealed that Suronacrine had a selective blocking action on the waveform associated with K+ currents.