A case study
Abstract: Leachables are traces of chemicals that may be found in medical devices originating from raw materials and fabrication processes that may result in exposure to patients. Testing for leachable as well as extractables should be conducted so as to reduce risk and increase confidence before biocompatibility test results. This case study presents a customer test for extractable study.
Author: Dr. Amir kraitzer
A customer is using a polycarbonate component in a laparoscopic surgery device. The product is in contact with skin only for a maximal duration of 24 hours. Bisphenol A may occur in polycarbonate plastics, epoxy resins and PVC. Bisphenol A was identified by the FDA as a possible hazardous.
Both the USP and the EP as well as ISO 10993 contain chapters that deal with the testing of plastic materials, including extraction tests. The customer requested to test for possible bisphenol A in the final product.
Definition of Extractables and Leachables
- Extractables are chemical entities (organic/inorganic) that will extract from components once exposed to certain solvents under controlled conditions. They are used to identify and quantify potential leachables.
- Leachables are chemical entities, both organic and inorganic, that migrate from components into the body over the course of time.
Extractable study is usually used at the beginning as a “worst-case scenario” so as to identify the possible “free” chemicals that might leach out eventually. This study is performed under exaggerated conditions usually using three types of solvents (polar, half polar and non-polar). At the next stage the chemicals that were identified during the extractable study may be screened during leachables study which is performed under simulated body conditions that depend upon the context: the chemical composition of the device, the liquid which may come in contact with the device, the duration and conditions of contact with the body.
Medibrane has performed an extractable study of the laparoscopic device according to ISO standards 10993-12 and ISO10993-18. The study included an incubation of the final product (post sterilization) in purified water at 37oC for 24 hours and then the medium was screened for biphenol A. The bishphenol A was screened using High Performance Liquid Chromatography (HPLC).
BPA was found in the water extractions within the calibration range of the HPLC and within the detection limits. The amount of BPA exceeded the allowable limits determined by a toxicologist. Accordingly, the customer had to replace its polycarbonate supplier and switch to a medical grade material supplier.