Increased thermal stability and retained antibacterial properties in a sulbactam and amantadine salt: towards effective antibacterial–antiviral combination therapies†

We describe the formation of a multidrug salt comprising sulbactam (SUL, β-lactamase inhibitor) and amantadine (AMNH, antiviral). Physicochemical investigation of the SUL·AMNH salt revealed enhanced thermal stability compared to pristine starting materials. In vitro studies found that salt formation in SUL·AMNH does not disrupt antibacterial activity against model organisms Escherichia coli and Staphylococcus epidermidis. To our knowledge, we show the first β-lactamase inhibitor-antiviral salt where both components have been approved by the U.S. Food and Drug Administration (FDA), and the first multicomponent solid containing SUL. We envisage our strategy could inspire the design of multicomponent solids for antimicrobial combination therapies.