Plastic is used extensively in modern medicine and the incorporation of plastic into a wide range of medical applications has been increasing steadily over the past decade - but a thermoformed plastic medical device that touches the human body? Is this safe? How is this controlled? How can we ensure that this material meets the proper requirements and approvals for pharmaceutical and medical applications? Bio compatibility is a critical factor for materials used in medical devices, and USP Class VI materials are specifically evaluated to meet these stringent requirements.
After completing the long validation protocols required for medical applications of process and machine, the next challenge is to find the right plastic material that is biocompatible, medical grade, FDA approved and passes all other required rules and regulations. One of the testing protocols commonly used to designate a plastic material safe for use in the manufacturing of medical devices is USP Class testing. Bio compatibility protocols, such as those outlined in USP Class VI, are designed to ensure materials are safe for use in medical and pharmaceutical applications.
So what is USP class testing? The United States Pharmacopoeia (USP) 30, NF 25, 2007 standard, also known as Class VI, is widely used to comply with stringent FDA regulations for products that come in contact with the human body. The USP outlines classes for plastic materials, i.e. I - VI, with USP Class VI being the strictest, requiring that the material exhibit very low levels of toxicity proven through a series of tests. These USP Standards are set for quality, purity, strength and consistency and published in the US Pharmacopeia and the National Formulary (USP NF).
To achieve USP Class VI certification, the material goes through a series of biological tests: (1) Systemic toxicity, (2) Intracutaneous reactivity, and (3) Muscle implantation. Each testing category includes a full range of tests, procedures and industry best practices for all phases of pharmaceutical and medical device development and manufacturing. These protocols are part of creating standards that help ensure safety and regulatory acceptance for medical device materials. A plastic material that has passed class VI certification is expected to be more likely to produce favorable biocompatibility results in order to eliminate the risk of adverse reactions in patients.
It should be noted that while USP Class VI is an important designation for plastics in medical, this certification is not a catch-all for medical applications as far as regulation is concerned: “While USP notes that these tests can be used for medical devices, regulatory agencies of the world generally will not accept a USP certificate in lieu of ISO 10993 testing. USP Class testing is most commonly used to designate a raw material as safe for use in manufacturing medical devices.” (Andrew Gottfried, NAMSA) Impact Plastics encourages customers to assess each application on a case-by-case basis to determine if USP Class VI plastic meet the requirements of their application. The goal of these standards is to ensure safety for patients and end-users.
With a number of misconceptions in the market regarding the biocompatibility of materials for medical & medical packaging applications, it is important to work with a plastic sheet extrusion partner that offers materials with the proper certifications for your thermoforming project to ensure that you are meeting important safety requirements. Click on the link below to learn more about our certified USP Class VI proprietary formulations: Impact Plastics offers USP Class VI materials that have been rigorously evaluated for bio compatibility and safety.
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Plastic Materials and Testing
Plastic materials intended for use in medical devices must meet exceptionally high standards for safety and biocompatibility. To ensure these requirements are met, USP Class VI testing is widely recognized as one of the most rigorous protocols in the industry. This testing is specifically designed to assess the biological reactivity of plastics materials in vivo, providing a comprehensive evaluation of their suitability for direct or indirect contact with human tissue.
USP Class VI testing consists of three critical tests: the Systemic Injection Test, the Intracutaneous Test, and the Implantation Test. Each of these tests plays a unique role in evaluating the safety profile of a plastic material. The Systemic Injection Test examines the potential for acute systemic toxicity by injecting extracts of the test material—prepared using solvents like polyethylene glycol, vegetable oil, and saline—into a test model. The Intracutaneous Test assesses localized irritation by injecting these extracts just beneath the skin, monitoring for any adverse local biological responses. The Implantation Test, often referred to as the third test, involves placing the plastic material directly into living tissue to observe any reaction over time, ensuring the material does not provoke harmful responses when in prolonged contact with human tissue.
The United States Pharmacopeia (USP) and the National Formulary (USP NF) have established six plastics classes, with USP Class VI representing the most stringent level. The USP defines the requirements for each class, but USP Class VI standards are particularly demanding, focusing on purity, strength, quality, and consistency. Plastics manufacturers find it advantageous to have their plastic resins and materials certified to this level, as it demonstrates a commitment to safety and regulatory compliance—especially for materials used in medical devices, surgical equipment, and other health care technologies.
Achieving USP Class VI certification involves testing the plastic materials with specific extracts, including both polar and nonpolar solvents, to simulate a range of conditions the material might encounter in real-world medical applications. The testing is performed to identify any potential for systemic toxicity or localized irritation, ensuring that the plastic materials do not cause adverse reactions in living tissue. This process is essential for producing favorable biocompatibility results and is a key step in the development and approval of medical devices.
The standards and guidelines provided by the USP NF are critical in creating a common standard for class plastics testing. These protocols help ensure public health by setting clear benchmarks for the quality and safety of plastics used in drug containers, o-rings, pharmaceutical tubing, and a variety of other medical device components. The USP Class VI certification is not only a mark of quality but also a requirement for many medical applications, as it assures manufacturers and end-users that the materials have undergone thorough evaluation for biological reactivity and systemic toxicity.
In summary, USP Class VI refers to the highest level of plastics classes defined by the United States Pharmacopeia, and the associated testing is considered the gold standard for biocompatibility and safety in medical device manufacturing. By passing the three tests—Systemic Injection, Intracutaneous, and Implantation—plastic materials demonstrate their ability to meet the most demanding requirements for use in medical devices, helping to ensure patient safety and the reliability of modern health care technologies.
