Scaffolds containing 7, 5, 5, and 6 rings, were predicted by their corresponding lead top-children for fexofenadine-, ebastine-, astemizole-, and mizolastine-derivatives, respectively (Figure , down). PyMol study of their corresponding H1R complexes predicted that all lead top-children docked to similar H1R site nearby amino acids in docking cavities specifically formed by α-helices III, V, VI and VII (Figure , up). In particular, the 842NN extended its terminal -COOH towards the extracellular H1R loops (Figure , red spheres), suggesting that terminal atom extensions could increase H1R both affinities and specificities.