Ethylene oxide (ETO) and gamma-irradiation (GR) are most commonly used for device sterilization by the biomedical industry. However, use of ETO and GR can be limited because of (l) degradation of certain radiation- sensitive devices such as those made of polypropylene (PP) and absorbable polyesters; (2) incomplete sterilization with ETO and its toxic residues, and (3) hazards in the sterilization facility due to the toxic and explosive nature of ETO. The recent availability of a novel radiochemical sterilization (RC-S) process comprising a combination of a controllably released formaldehyde, and low-dose (equal to or less than 7.5 KGy) GR, and importance of PP and absorbable sutures justified pursuing the proposed study. Phase I objective is to determine the feasibility to sterilize, radiochemically, PP and polyglycolide (PG), as an absorbable suture in a sealed package without compromising, significantly, its in vivo and in vitro properties. Phase I plans entail (1) using available data on RC-S to determine of PP and PG sutures sterility and effect of 5 and 7.5 Kgy irradiation, under nitrogen, on tensile properties in a foil package; (2) determining amount of residual formaldehyde (if any) in the different components of the package and suture; (3) repeating segment 1 using needled sutures and determining effect on needle properties; (4) conducting segment l at selected doses using two sizes of PP and PG sutures and evaluate their in vivo performance over a 3-week period; and (5) analyzing the results and selecting an optimum range of conditions for packaging and sterilization toward validating the process for PP and PG sutures in Phase II. Phase II study will include (l) determining effects of RC-S experimental variables; (2) assessing applicability of the RC-S process to complex devices; (3) ascertaining absence of harmful formaldehyde levels in sterilized packages and package stability; and (4) initiating the FDA approval process.
Primary outcome of a successful Phase I is demonstrating feasibility of sterilizing polypropylene and polyglycolide sutures using the radiochemical process without compromising their in vitro and in vivo performance and package components. Phase I results will provide basic data for process development and validation in Phase II. The long-term impact will be the availability of a new, low-dose radiation process for radiation-sensitive devices which represent a major milestone in sterilization technology.
