Development of a new drug delivery system for protein drugs using silicone (II).

In order to achieve a zero-order release of protein drugs, we have developed a new drug delivery system using silicone, which is named the covered-rod-type formulation. Preparation of the covered-rod-type formulation was conducted under mild conditions without heat treatment or the use of organic solvents. The covered-rod-type formulation released human serum albumin (HSA) or interferon (IFN) at a constant rate for 30-100 days in vitro without significant initial burst. When the IFN covered-rod-type formulation was implanted in nude mice, the serum IFN concentration was maintained at a constant level during the period of observation, i.e., 28 days. The covered-rod-type formulation enabled precise control of the release of the protein drugs and would be expected to increase the duration of the drug effect and to reduce the frequency of administration and side effects.