A computer implemented method for determining the suitability of an antibody for inclusion in a pharmaceutical composition, wherein the method comprises: (a) setting a viscosity limit for the antibody associated with a fitness of the antibody for manufacturing or therapeutic dispensing; (b) calculating, from the information of a primary structure of the antibody, a net charge and a charge asymmetry at a certain pH, wherein the primary structure comprises: a light chain variable domain amino acid sequence and a heavy chain variable domain amino acid sequence; (c) obtaining a first scaling factor and a second scaling factor, wherein the scaling factors are coefficients of an objective function that yields a viscosity index, wherein obtaining the scaling factors comprises: fitting the objective function to data comprising (i) data of a plurality of viscosity measurements of at least one test antibody, each of the viscosity measurements taken under a different solution condition, wherein the at least one test antibody comprises a plurality of antibodies, and (ii) a net charge and a charge asymmetry of each of the at least one test antibody, wherein the antibody and the at least one test antibody are of the same antibody class, the first scaling factor corresponds to the net charge and the second scaling factor corresponds to the charge asymmetry, and the objective function includes a summation of multiplicative products of (i) the values of structural parameters comprising the net charge and charge asymmetry, and (ii) corresponding scaling factors comprising the first scaling factor and the second scaling factor; (d) calculating the viscosity index for the antibody using the objective function comprising the scaling factors, the net charge of the antibody, and the charge asymmetry of the antibody, the viscosity index representing the viscosity of the antibody; and (e) responsive to the viscosity index not exceeding the viscosity limit, determining the antibody's suitability. (a) setting a viscosity limit for the antibody associated with a fitness of the antibody for manufacturing or therapeutic dispensing; (b) calculating, from the information of a primary structure of the antibody, a net charge and a charge asymmetry at a certain pH, wherein the primary structure comprises: a light chain variable domain amino acid sequence and a heavy chain variable domain amino acid sequence; (c) obtaining a first scaling factor and a second scaling factor, wherein the scaling factors are coefficients of an objective function that yields a viscosity index, wherein obtaining the scaling factors comprises: fitting the objective function to data comprising (i) data of a plurality of viscosity measurements of at least one test antibody, each of the viscosity measurements taken under a different solution condition, wherein the at least one test antibody comprises a plurality of antibodies, and (ii) a net charge and a charge asymmetry of each of the at least one test antibody, wherein the antibody and the at least one test antibody are of the same antibody class, the first scaling factor corresponds to the net charge and the second scaling factor corresponds to the charge asymmetry, and the objective function includes a summation of multiplicative products of (i) the values of structural parameters comprising the net charge and charge asymmetry, and (ii) corresponding scaling factors comprising the first scaling factor and the second scaling factor; (d) calculating the viscosity index for the antibody using the objective function comprising the scaling factors, the net charge of the antibody, and the charge asymmetry of the antibody, the viscosity index representing the viscosity of the antibody; and (e) responsive to the viscosity index not exceeding the viscosity limit, determining the antibody's suitability.