The development of pharmaceutical formulations of monoclonal antibodies is of vital importance to achieve effective and safe drugs. Hence, many research groups have focused on using different screening strategies to optimize the formulation for each antibody under study. Within the excipients used to carry out the screening of formulation are carbohydrates, salts, surfactants and amino acids. In our work we focused specifically on a monoclonal antibody aHer2 for the treatment of breast cancer type Her2 positive. For the characterization of these formulations were used methods such as dynamic light scattering, size exclusion chromatography, UV spectrophotometry, among others. As results of the work, was demonstrated the effectiveness of the stepwise screening methodology to select the best formulation variants. In addition, the presence of excipients as carbohydrates improves the stability of the formulation unlike the presence of sodium chloride.