Abstract: Known quinolone carboxylic acid derivatives of the formula ##STR1## are treated so as to become readily administrable parenterally, the treatment comprising dissolving the active compound using an acid, allowing the solution to stand for about 0.15 to 150 hours at a temperature from room temperature to the boiling point of the solution, filtering the solution, precipitating the active compound from the solution using a basic reagent, and converting the precipitated active compound into a form which can be administered parenterally.

Abstract: In the preparation of a 1,4-dihydropyridine of the formula ##STR1## in which R is a phenyl radical which is optionally substituted once or twice by nitro and/or chlorine,R.sub.1 is a C.sub.1 -C.sub.4 -alkyl radical which is optionally substituted by a C.sub.1 -C.sub.4 -alkoxy group, andR.sub.2 is a C.sub.1 -C.sub.12 -alkyl radical which is optionally substituted by a C.sub.1 -C.sub.4 -alkoxy group, a trifluoromethyl group or the radical (C.sub.6 H.sub.5 CH.sub.2) (CH.sub.3)N,by preparing an ylidene compound of the formula ##STR2## and reacting such ylidene compound with an enamine compound of the formula ##STR3## the improvement which comprises preparing the ylidene compound by reaction of a ketocarboxylic ester of the formula ##STR4## with an aldehyde of the formula RCHO, in a solvent in the presence of a catalytic amount of any acetate salt of an amine, at a temperature from about -10.degree. C. up to 100.degree. C. The products symmetrical or unsymmetrical, are produced in high yield and purity.