Soluble calcium lactate antibacterial complexes as non-irritating parenteral forms

A storage stable soluble calcium lactate antibacterial complex in parenteral dosage form, comprising in solution a) a lactic acid salt of a carboxylic acid antibacterial compound corresponding to 1 to 3 moles of lactic acid per mole of the antibacterial compound, the antibacterial compound being selected from

• 1) a quinolone of formula ##STR4## wherein A is aminomethyl, ethylaminomethyl or amino;
• 2) a naphthyridine of formula ##STR5## or an optical isomer thereof, wherein B is 2-amino-1-oxopropylamino, amnioacetylamino, (2-amino-1-oxo-3-phenylpropyl)amino, (2,5-diamino-1,5-dioxopentyl)amine, (2-amino-4-carboxy-1-oxobutyl)amino, (2,6-diamino-1-oxohexyl)amino, or (aminophenylacetyl)amino, or
• 3) a naphthyridine of formula ##STR6## or an optical isomer thereof, wherein C' is [(2-amino-1-oxo-3-phenylpropyl)amino]methyl, [(2-amino-1-oxopropyl)amino]methyl, [(aminoacetyl)amino]methyl, [(aminophenylacetyl)amino]methyl, [(2-amino-4-carboxy-1-oxobutyl)amino]methyl, [(2,6-diamino-1-oxohexyl)amino]methyl, or [(2,5-diamino-1,5-dioxopentyl)amino]methyl;
• and b) calcium hydroxide in a quantity that is selected so that the pH of the solution is between about 4.0 to about 5.5, precipitation of the antibacterial compound from the solution is avoided and yet on injection irritation by the solution is absent or minimized.