Cancer is a disease that can affect any region of the body. Cancer from other organs may also spread to the lungs. Epidermal growth factor receptor (EGFR) is majorly responsible for the growth and development of pancreatic and lung cancer. Erlotinib belongs to the reversible tyrosine kinase inhibitor class of drugs which is give to cure non small cell lung cancer and advanced pancreatic cancer. It acts mainly upon the epidermal growth factor receptor (EGFR) which belongs to ErbB receptor family. Polymeric PLGA nanoparticles were prepared employing a modified single emulsification (o/w) comprising solvent evaporation method. In the modified method, Erlotinib (150 mg) and PLGA at different concentrations i.e., 50, 75 and 100mg; both were solubilized in Dimethyl Sulfoxide (4 ml) to make an organic phase in one beaker vessel. In some other glass beaker, an aqueous phase was made by adding Tween 80 using different concentrations like 70, 95 and 120 mg. An o/w emulsion was constituted further by mixing both the aqueous and organic phase together using probe sonicator at different time 3, 5.5, 8 min. The optimized nanoparticles were obtained with particle size range which can be effective in prolonging the circulation time of the drug helping in the delivery of the drug at the target site. The mathematical developed models can be used further for the formulation of nanoparticles with the desired characteristics.