A novel crystalline molecular salt of sulfamethoxazole and amantadine hybridizing antiviral-antibacterial dual drugs with optimal in vitro/vivo pharmaceutical properties.

In order to exploit the advantages to the full of multidrug salification strategy in amending the pharmaceutical properties of drugs both in vitro and in vivo, and further to open up a new way for its applications in bacteria-virus mixed cross-infection drugs, a novel dual-drug crystalline molecular salt hybridizing antibacterial drug sulfamethoxazole (SFM) with antiviral ingredient amantadine (ATE), namely SFM-ATE, is successfully designed and synthesized via multidrug salification strategy oriented by proton exchange reaction. The crystal structure of the firstly obtained molecular salt is precisely identified by employing single-crystal X-ray diffraction and multiple other techniques. The results show that, in the crystal lattice of molecular salt SFM-ATE, the classical hydrogen bonds together with charge-assisted hydrogen bonds contribute to two- dimensional networks, between which the hydrophobic interaction plays an important role. The relevant in vitro/vivo pharmaceutical properties of the dual-drug molecular salt are carried out through a comparative investigation of theoretical and experimental methods. It has been found that SFM displays concurrent improvements over the bulk drug in its permeability and dissolution after forming the molecular salt, which is supported by the molecular electrostatic potential calculation and Hirshfeld surface analysis. Encouragingly, the perfected in vitro biopharmaceutical properties can effectually turn into the in vivo pharmacokinetic preponderances with the expedited peak plasma concentration, lengthened half-life and enhanced bioavailability. Better yet, the antibacterial activities of SFM from the molecular salt get stronger with enlargement in inhibition areas and reduction in values of minimum inhibitory concentrations against the tested bacterial strains. Consequently, the present contribution not only supplies an opportunity for widening applications for classical sulfa drugs via dual-drug salification strategy, but also offers an alternative approach in dealing with viral-bacterial coinfection even other complex diseases by drugs' hybridization at the molecular level.
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