METHOD OF CONTROLLING pH IN THE VICINITY OF BIODEGRADABLE IMPLANTS, AND METHOD OF INCREASING SURFACE POROSITY

摘要

The invention discloses pH-controlling devices that comprise a biodegradable polymer and a pH-controlling substance, particularly an alkaline, acidic or buffering agent. By way of example, such alkaline agents include calcium carbonate and sodium bicarbonate. Methods of preparing such devices are also described. Methods for enhancing biocompatibility of an implantable device are also provided, as neutralizing alkaline materials are released at a rate that offsets changes in pH typically observed as polymers degrade to various acidic or alkaline by-products. By way of example, biodegradable polymers include PLA, PGA, polycaprolactone, copolymers thereof, or mixtures thereof. New techniques are also disclosed to increase the surface porosity of porous implants which have a tendency to form relatively impermeable coverings. These techniques entail the use of mechanical means to remove at least part of said covering or to "punch" out implants from pre-fabricated slabs or sheets, thus increasing the implant's surface porosity and permeability.