Binary and Ternary Complexes of Arteether β-CD - Characterization, Molecular Modeling and in Vivo Studies

The purpose of the present work is to improve the antimalarial activity of arteether through enhancing its solubility subsequently bioavailability by incorporating the drug into the cyclodextrins cavity. The effect of hydrophilic polyvinyl propylene (PVP) polymer on the complexation and solubilizing efficiencies of cyclodextrins (CDs) is also elucidated. Inclusion of arteether molecule in solid state was evidenced by Differential scanning calorimeter (DSC), Powder X-ray diffractometery (PXRD), and in solution state by NMR and solution calorimetry. A 1:1 stoichiometry was proposed by the phase solubility studies both in presence and absence of PVP. The most plausibe mode of inclusion of arteether into the CD cavity is revealed by molecular modeling studies utalizing Fast Rigid Exhaustive Docking acronym. Solution calorimetry was used further to confirm 1:1 stiochiometry in presence or absence of PVP by determining the enthalpy of interaction between the drug and cyclodextrins. The inclusion of drug was found to be exothermic process accompanied by small positive value of entropy (ΔSo). The methylated-β-CD showed the best ability to solublize arteether which is approximately at par with β-CD in the presence of PVP. Better complexation efficiency of β-CD in presence of PVP is also reflected by the higher numerical values of stability constant (K). Compelete eradication of the parasite from the blood and highest anti-malarial pharmacological activity was observed in the complexes of arteether with M-?-CD while 83.7% was observed for ternary complexes of β-CD in presence of PVP.