Enhanced bioaccesibility of selective PDE4 inhibitor N-(3,4-dihydro-2h-1,5-benzodioxepin-7-yl) pyridine-4-carboxamide using polyamidoamine dendrimer

Abstract

The aim of this study was to improve the aqueous solubility of highly hydrophobic but selective PDE4 inhibitor N-(3,4-dihydro-2h-1,5-benzodioxepin-7-yl) pyridine-4-carboxamide by associating it with polyamidoamine dendrimer. The PAMAM dendrimer restraining ethylenediamine core synthesized by a divergent approach was utilized for encapsulation. The solubility of conjugates was evaluated on the basis of concentration and generation of the dendrimer, pH of the solution, and temperature. The phase solubility diagram confirmed an increase in aqueous solubility of drug with increase in dendrimer concentration with respect to pH in the order 9.0 > 7.0 > 4.0. Moreover, values of thermodynamic parameters such as negative value of ΔHo, positive value of ΔSo and ΔGo reflects an exothermic complexation, presence of number of particles and spontaneity of the complexation. Overall, investigations validate the enhancement in solubility of drug after complexation with polyamidoamine dendrimer which further confirmed promising bioactivity of the drug-dendrimer conjugates.