Enrofloxacin (1- cyclopropyl - 7 - (4 - ethyl - 1 - piperazinyl) - 6 - fluoro - 1,4 - dihydro - 4 - oxo - 3 quinolone carboxylic acid) belongs to the group of synthetic 6-fluoroquinolones or 4-quinolones derived from the core structure of nalidixic acid (see picture). As a result of gradual changes to the basic molecule, antibiotic properties were considerably increased and pharmacokinetics could be substantially improved, whereas the probability of undesired side effects was reduced.
Enrofloxacin is a pale yellow, crystalline substance with a high degree of purity. In water at pH 7, it is slightly soluble. However, as it contains acidic and basic groups (betaine structure), it can readily be brought into solution when the pH values are either alkaline or acidic. Liquid formulations of Baytril® for parenteral administration contain freely soluble salts of enrofloxacin in an aqueous solution. Due to the high hydrolytic stability of the active ingredient, these solutions are very stable. The tablet formulations contain enrofloxacin in its original betaine form.