A poro-viscoelastic model for the subcutaneous injection of monoclonal antibodies

Subcutaneous delivery of therapeutic monoclonal antibodies (mAbs) has recently attracted exceptional interests in the pharmaceutical industry. The mechanical response of the tissue during the injection and the drug distribution after the injection are yet to be understood. We are motivated to study the subcutaneous injection using a nonlinear poro-elastic model with a viscoelastic constitutive law of the solid. The model is first validated against experimental data of relaxation tests. Then the poro-viscoelastic model is applied to subcutaneous injection, and is compared against a poro-hyperelastic model. The pressure at the injection site, which serves as an indicator of possible fracture initiation, differs significantly by taking into account the viscosity of the solid.