The biocompatibility of ethylene‐vinyl acetate copolymer (EVAc), polyethylene (PE), and polyaniline (PANi) films in the emeraldine (EM), nigraniline (NA) and leucoemeraldine (LM) intrinsic oxidation states were assessed through subcutaneous implantation into male Sprague‐Dawley rats beneath the dorsal skin, for a period ranging from 19 to 90 weeks. Histological examination, interstitial pressure measurement, and X‐ray photoelectron spectroscopy (XPS) were employed to determine the biocompatibility of the polymers. The polymers did not provoke inflammatory responses in the subcutaneous tissues over the entire implantation period. Characteristics features associated with tissue–implant incompatibility were not evident near the implantation. Interstitial pressure was measured to evaluate the development of tissue. Low interstitial pressure readings on the region of implantation confirmed the biocompatibility of these polymer types. The surface composition of the electroactive aniline polymers before and after the implantation was characterized by XPS. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 52, 467–478, 2000.

The biocompatibility of ethylene-vinyl acetate copolymer (EVAc), polyethylene (PE), and polyaniline (PANi) films in the emeraldine (EM), nigraniline (NA) and leucoemeraldine (LM) intrinsic oxidation states were assessed through subcutaneous implantation into male Sprague-Dawley rats beneath the dorsal skin, for a period ranging from 19 to 90 weeks. Histological examination, interstitial pressure measurement, and X-ray photoelectron spectroscopy (XPS) were employed to determine the biocompatibility of the polymers. The polymers did not provoke inflammatory responses in the subcutaneous tissues over the entire implantation period. Characteristics features associated with tissue-implant incompatibility were not evident near the implantation. Interstitial pressure was measured to evaluate the development of tissue. Low interstitial pressure readings on the region of implantation confirmed the biocompatibility of these polymer types. The surface composition of the electroactive aniline polymers before and after the implantation was characterized by XPS.

The release of human immunoglobulin G (IgG) using ethylene-vinyl acetate copolymer (EVAc) as a polymer carrier was studied by fabricating them into two commercially available dosage forms: slab and microsphere. A first-order flux decay model and two hierarchical models concerned with the mass transfer coefficient on the slab surface were used to describe the mechanism of release kinetics and the results compared. These models gave insight to some of the important physical parameters of drug release such as the diffusion coefficient, time constant of release, and initial flux. It was found that the release mechanism varies with time, and hence no single model can be used to predict the release profile for the entire period of study. A controlled release study by matrix coating was also done. The results obtained were utilized to examine the suitability of a particular dosage form (matrix geometry) of IgG for clinical applications. The release data compared with the standard methods of IgG therapy proves localized drug delivery to be a major boon for immunodeficient patients.

Human immunoglobulin G (IgG) serves as an important chemotherapeutic agent for a number of immunological ailments and as a carrier in the targeted delivery of other therapeutic agents. This paper deals with the characterization of IgG-dispersed monolithic matrixes of different geometries, prepared using a nonbiodegradable polymer carrier EVAc. The morphological changes associated with the matrix during drug release was studied using scanning electron microscopy, polarizing microscopy, atomic force microscopy, and X-ray photoelectron microscopy, and the results were compared. The study answered the burst effect problem significantly and illustrated the potential of these techniques in understanding the morphological structure of matrixes and mode of release kinetics.