Studies on charge-transfer and hydrogen bond formation with cyproheptadine

Cyproheptadine, an antihistaminic and antipruritic drug, forms fairly stabl e charge-transfer complexes with quinone (Q), chloranil (Chl-Q) and anthraq uinone (AQ) in chloroform. It also forms stable hydrogen bonds with alcohol s (methanol and propanol) and phenols (alpha -naphthol, p-cresol and p-chlo rophenol). A rough correlation has been observed with log K of hydrogenbond ed complexes with pK-values of phenols. The results suggest that cyproheptadine can form loose association with rec eptors through charge-transfer and hydrogen bond complex formation.