Inflammatory response to intramuscular implantation of polyacrylonitrile ultrafiltration probes in sheep

Polyacrylonitrile is used in the manufacture of dialysis membranes. These m embranes are fundamental to the functioning of implantable probes for micro dialysis and ultrafiltration sampling of tissue fluids. Although in vivo ex perimentation using polyacrylonitrile has been reported to cause little inf lammatory response when implanted subcutaneously, such information is not a vailable for intramuscular implantation in sheep. The procaine and benzathi ne salts of penicillin are formulated for intramuscular injection. These sa lts of penicillin or the formulation excipients may cause inflammatory reac tions. Use of polyacrylonitrile probes to draw samples from sites at which these formulations have been injected may be compromised by inflammation or direct interaction between formulation excipients and the dialysis membran e. The aim of this project was to describe tissue responses to intramuscula r implantation of polyacrylonitrile in the presence and absence of either p rocaine or procaine plus benzathine salts of penicillin G. Each of 20 norma l sheep was implanted with two ultrafiltration probes, one at the site of a n injection of procaine or benzathine plus procaine penicillin G. Similar i njections were also made at remote intramuscular sites. After 8, 9, and 11 days of the experiment, sheep were killed and the injection and implantatio n site muscle were excised and prepared for histopathological examination. The implantation of the probe alone caused greater inflammatory response th an the injection of procaine or procaine plus benzathine penicillin G at re mote intramuscular sites. The histopathological lesions were greatest where the implantation site was coupled with the injection of either formulation of penicillin G. Polyacrylonitrile may not be a suitable dialysis membrane material for intramuscular implantation in sheep.