Plastics used in medical technology

Plastics used in medical technology

Exist components and profiles made of thermoplastics which are designed to comply with the stringent demands of medical technology. The special demands imposed on these materials such as physiological safety are addressed by the outstanding properties of high temperature plastics:

Examination of the semi-finished product for biocompatibility
Very good resistance to cleaning agents and disinfectants
Resistance against common sterilization methods such as hot steam, hot air, ethylene oxide or gamma radiation
Compliance examination of the used processing agents
Attentive storage and shipment with shrink packing.

It is the combination of these Medical-Technology-portfolio attributes that allows this type of high-quality medical products to be used intensively over long periods.
In many cases, plastics replace metals or ceramics. They often provide the only alternative when it comes to the implementation of unusual technical applications.

Medical Technology plastics are generally produced from raw materials conforming to stringent FDA requirements.
These properties and their specific resistance to sterilization make them ideally suited to use in the medical and pharmaceutical industry.

In each of these sectors, objects derived from plastic materials for medical use are used:

Trauma / Orthopaedics
Surgery
Diagnostics
Therapy
Intensive care / ventilation
Dental medicine
Sterilization

Sterilization-resistant materials MT (Medical Technology)

High number of sterilization cycles

(PPSU MT) – (PPS MT) – (PEEK MT)
Function: Very high resistance over a large number of sterilization cycles.
Benefit: Components made of these materials have a long service life, so reducing the cost of repeat purchasing.

Limited number of sterilization cycles

(PP MT) – (POM-C MT) – (PC MT) – (PE MT) – (PPE MT)
Function: Sterilization resistance for a limited number of cycles, comparably favourable material costs.
Benefit: Optimized cost ratio for components which are only required to be sterilized and re-used infrequently.

X-ray detectable MT materials

(PEEK MT) – (PPSU MT)
Function: Clear visibility under fluoroscopy and X-ray radiation.
Benefit: During image-controlled procedures, the surgeon has an exact picture of the plastic components.

Antimicrobial materials

(PP MT) – (POM-C MT)
Function: Antimicrobial effect by the release of biocides.
Benefit: Reduction of microbes in day-to-day medical and clinical use.

High-strength MT materials

(PEEK+ carbon fibres MT)
Function: Unusually high mechanical strength and dimensional stability.
Benefit: Extremely accurate and precise operation in the field of orthopaedic surgery.

Transparent MT materials

(PC MT) – (PPSU MT) – (PEI MT)
Function: Transparency simplifies optical control.
Benefit: Visible components plus biocompatibility.

Biocompatibility

Biocompatibility is the measure of the compatibility of a material with the tissue or physiological system of the patient. It provides information on whether a plastic or its degradation products give off toxic products or provoke an allergic reaction. In principle, the function of both ISO 10993 and USP is to verify the biological qualification of a material or product. Depending on the product in question and the field of application, the following standards are determining factors or can provide valuable assistance in evaluating a product or material.

ISO 10993

The international standard ISO 10993 is of relevance particularly to manufacturers of medical products and test laboratories, and is now the acknowledged guideline for medical products. The aim of this standard is to evaluate the materials used in terms of their suitability for direct body contact. The described strategy for biological qualification applies initially to
medical products, but can also be used for evaluation and assessment of their pre-products (such as plastic semi-finished products).
This allows the material to be pre-qualified before its use in a medical product, reducing the risks entailed in subsequent application. For biological-toxicological assessment of medical products in compliance with ISO 10993-1, it makes sense to start with a product categorization to determine the hazard level and the requirement profile for the material in the relevant medical application. The available toxicological data relating to the used material is then checked in order to analyse and evaluate the possible biological effects in a step by step process. On the basis of the results, a decision is then taken as to which toxicological tests are necessary for a final evaluation and whether an alternative material may have to be used.
Alongside the description of biological-toxicological tests, since 2003 the ISO 10993 standard has also included physical-chemical tests for the identification of potentially toxic and allergenic materials or substances. In concrete terms, the ISO 10993 standard is subdivided into sections 1-20 from the preparation of samples and evaluation of tests through the
chemical characterization of materials to immunotoxicological tests. The requirements imposed on the biological qualification of medical products in accordance with ISO 10993 depend not only on the type of medical product, but at the same time also:

on the place of use (skin, mucous membrane, blood, tissue)
on the intended function (contact with body surfaces, internal body contact, implantable product) and
on the period of use (< 24 hours, < 30 days, unlimited)

USP

The United States Pharmacopeia Convention (USP) is an organization for the evaluation of packaging used for pharmaceutical products. It compiles with standards relating to quality, purity and identity, and checks products manufactured world wide and generally sold, consumed or used in the USA. The USP is a fundamental requirement specifically for pharmaceutical products and their manufacturing technologies. However, for medical products, the role of the USP is only to provide a supportive statement for qualification. Statements on the biological risk assessment of a material in accordance with USP tests can be derived from alternative tests in compliance with ISO 10993. This leads to a situation where, in the case of new developments in particular, the USP has been increasingly superceded by the ISO 10993 in recent years.
The USP <87> and <88> can be consulted for the assessment of components / products made of plastic. USP <87> describes the cyctotoxicity test which does, however, differ in certain details from the ISO 10993-5. The USP <88> divides products into categories I-VI, whereby the products of category VI have to comply with the most stringent requirements and consequently have to complete extensive testing. This so-called “in-vivo screening” for the fundamental assessment of the biocompatibility of a plastic are used to test acute systemic toxicity, irritation and also includes a short-term implant test.

FDA-compliance

Alongside the evaluation of a material’s suitability for contact with food, FDA compliance is frequently also used in the field of medical technology to provide users with important information on risk assessment. However, it is not a binding requirement for the use of materials in the medical or pharmaceutical field. The American Food and Drug Administration (FDA) assesses the suitability of materials for direct and indirect contact with food. Raw materials, additives and properties of plastics are specified by the FDA in the “Code of Federal Regulations” CFR 21. Materials that meet the relevant requirements are regarded as FDA compliant.

A FDA-compliant formulation is valid without time limitation, as long as the raw materials are not changed. For this reason, only the manufacturer of a product may issue this FDA certificate, as only he/she knows the formulation and can guarantee that FDA-compliant raw materials are used. As raw materials for use in the medical sector mostly comply with the requirements of the FDA, this can be certified accordingly on an order-by-order basis in order to guarantee seamless traceability.