HRH3 and nervous system disorder: Ciproxifan is frequently used as the reference histamine H3 receptor (H3R) antagonist in rodent models for neurological diseases like cognition6, Alzheimer’s disease7 or sleep-wake disorders10, 17, because of its explicit high affinity and efficacy in rodent H3R (Ki < 1.0 nM) which is about 30- to 100-fold lower than that at the human H3R.