Part I of these stability studies commented on the benefits, in terms of care and therapy, of the Y administration of antibiotics and parenteral nutrition. The aim of this study is to determine the stability of the cephalosporins ceftazidime, ceftriaxone, ceftizosime and cefotaxime in vitro, at therapeutic concentrations, infused together with a parenteral nutrition mixture with polyols, enriched in branched chained amino acids, and without lipids. A microbiological stability analysis was carried out on the antibiotics in the parenteral nutrition, and an HPLC aminogram was done to determine the concentration of amino acids in the infusion together with the antibiotic. As well, pH, osmolarity and colour change were measured in the antibiotics, in the parenteral nutrition used and in the joint infusion mixtures. It is concluded that parenteral nutrition can be jointly infused with cefotaxime and ceftazidime, at the concentrations studied, given the stability results obtained both with HPLC (antibiotics and amino acids) and microbiologically (antibiotics). At the same time, the microbiological analysis of ceftriaxone with the nutrition showed its stability in the study conditions. Its joint infusion with parenteral nutrition, studied by HPLC, confirmed the stability of the amino acids. The ceftizoxime analysed by HPLC remained stable during joint infusion with the parenteral nutrition.