THE PRESENT INVENTION RELATES TO STORAGE STABLE AQUEOUS INFUSIBLE OR INJECTABLE SOLUTIONS CONTAINING AN ACTIVE SUBSTANCE OF GENERAL FORMULA (Ι) WHEREIN THE GROUPS L, R¹, R², R³, R⁴AND R⁵ HAVE THE MEANINGS GIVEN IN THE CLAIMS AND IN THE SPECIFICATION, AND AN AMOUNT OF A PHYSIOLOGICALLY ACCEPTABLE ACID OR MIXTURE OF ACIDS SUFFICIENT TO DISSOLVE THE ACTIVE SUBSTANCE AND ACT AS A STABILISER, OPTIONALLY TOGETHER WITH OTHER FORMULATING EXCIPIENTS SUITABLE FOR PARENTERAL ADMINISTRATION, AND A PROCESS FOR PREPARING THE INFUSIBLE OR INJECTABLE SOLUTIONS ACCORDINIG TO THE INVENTION.