It was found that finafloxacin has a high solubility in the presence of Tris. Such solubility is significantly higher than in the presence of other compounds typically used as buffers (e.g. phosphate buffer). The observed significant increase in solubility of finafloxacin in compositions comprising Tris is further advantageously accompanied by a long term stability of such solutions. Tris is therefore to be regarded as a specific tool to considerably enhance the solubility of finafloxacin in solutions. By preparing compositions comprising Tris it is possible to dissolve finafloxacin in such an amount therein that these compositions can effectively be used as parenteral compositions for the treatment of bacterial infections.
