¹Genveon Pharmaceutical Company, Research and Development Department, İzmit, Turkey DOI : 10.29228/jrp.2022.00 The pH optimization and EDTA are widely used in pharmaceutical formulations. The aim of the research work was to evaluate the pH effect and develop a including stable paraben pharmaceutical product. pH of final product is most important critical quality attributes (CQA). Variability pH of formulation is affecting paraben stability. Therefore, chemical stability may affect paraben assay, so this CQA was be evaluated throughout parenteral formulation. A total of four formulations were designed to the stability study. To improve the stability of paraben formulations (T1-T4) were evaluated with different pH ranges and EDTA during stability period. Stability studies were performed to assay analysis of methyl paraben and propyl paraben. The rate of assay results was compared to T1-T4 formulations. As a result of paraben assay analysis for T2 formulation was found to be within in specification limit. The one of them were determined to the best formulations for paraben stability during stability periods. The research proposes a novel stable formulation and proper storage conditions for paraben parenteral solutions. The instability problem of paraben formulation was optimized with targeted pH modification. Keywords : Drug stability; excipient; methyl paraben; parenteral formulation; propyl paraben