An aqueous anti-infective injectable solution comprising: (i) from 15 to 20% by weight based on the total volume of the solution of at least one compound having the following formula: - X represents a hydrogen atom, a halogen atom or a hydroxy function, - R1 represents: • a 1-piperazinyl radical which may be substituted in the 4-position with methyl, acetyl or 4-aminobenzyl group; • a morpholino radical; • a 1-pyrrolidinyl radical substituted in the 3-position with a chlorine atom or by an amino, aminomethyl, (methylamino)methyl, (ethylamino)methyl or methoxy group; • a 1-imidazolyl radical which may be substituted in the 4-position with a methyl groupe or • a 1-piperidyl radical substituted in the 4-position with a hydroxy or methoxy group, and - R2 represents a linear, branched or cyclic alkyl radical containing from 1 to 10 carbon atoms, or at least one of its pharmaceutically acceptable salts, (ii) a stabilizing agent selected from the group comprising alcohols, propylene glycols, polyethylene glycol and glycerine, and (iii) at least one solubilizing agent selected from the group comprising mineral acids, organic acids and esters thereof, and mixtures thereof, in a pharmaceutically acceptable carrier. (i) from 15 to 20% by weight based on the total volume of the solution of at least one compound having the following formula: - X represents a hydrogen atom, a halogen atom or a hydroxy function, - R1 represents: • a 1-piperazinyl radical which may be substituted in the 4-position with methyl, acetyl or 4-aminobenzyl group; • a morpholino radical; • a 1-pyrrolidinyl radical substituted in the 3-position with a chlorine atom or by an amino, aminomethyl, (methylamino)methyl, (ethylamino)methyl or methoxy group; • a 1-imidazolyl radical which may be substituted in the 4-position with a methyl groupe or • a 1-piperidyl radical substituted in the 4-position with a hydroxy or methoxy group, and - R2 represents a linear, branched or cyclic alkyl radical containing from 1 to 10 carbon atoms, or at least one of its pharmaceutically acceptable salts, - X represents a hydrogen atom, a halogen atom or a hydroxy function, - R1 represents: • a 1-piperazinyl radical which may be substituted in the 4-position with methyl, acetyl or 4-aminobenzyl group; • a morpholino radical; • a 1-pyrrolidinyl radical substituted in the 3-position with a chlorine atom or by an amino, aminomethyl, (methylamino)methyl, (ethylamino)methyl or methoxy group; • a 1-imidazolyl radical which may be substituted in the 4-position with a methyl groupe or • a 1-piperidyl radical substituted in the 4-position with a hydroxy or methoxy group, and • a 1-piperazinyl radical which may be substituted in the 4-position with methyl, acetyl or 4-aminobenzyl group; • a morpholino radical; • a 1-pyrrolidinyl radical substituted in the 3-position with a chlorine atom or by an amino, aminomethyl, (methylamino)methyl, (ethylamino)methyl or methoxy group; • a 1-imidazolyl radical which may be substituted in the 4-position with a methyl groupe or • a 1-piperidyl radical substituted in the 4-position with a hydroxy or methoxy group, and - R2 represents a linear, branched or cyclic alkyl radical containing from 1 to 10 carbon atoms, or (ii) a stabilizing agent selected from the group comprising alcohols, propylene glycols, polyethylene glycol and glycerine, and (iii) at least one solubilizing agent selected from the group comprising mineral acids, organic acids and esters thereof, and mixtures thereof,