The effect of HPMC and MC as pore formers on the rheology of the implant microenvironment and the drug release in vitro.

•Water soluble cellulose ethers, HPMC and MC, were used to tailor the porosity and drug release from hot melt extruded model implants.•Leached HPMC pore former increased the viscosity of the implant microenvironment in vitro, while MC had a negligible effect in the viscosity.•HPMC pore formers resulted in higher implant porosity and total drug release, whereas MC resulted in lower porosity, with slow, extended release.•Dissolving polymeric pore formers change the rheological properties of the implant microenvironment both in the pores and around the implant.•Viscosity changes may have an important effect on the diffusion of the drug and other molecules in the biological fluids in the implantation site.