What the End of USP Class VI Means for Medical Manufacturers

For decades, USP Class VI has been a benchmark for material safety among medical device and component manufacturers. This standard applies to various medical polymers, but it’s long been associated with silicones because these elastomers are used extensively in medical seals, gaskets, and tubing.  

Design engineers and compliance teams put “USP Class VI compliant” on technical drawings and material specifications as shorthand for biological safety. Now that shorthand is changing. The United States Pharmacopeia (USP), a non-profit organization that publishes quality standards for medicines, dietary supplements, and food ingredients, is phasing out USP Class VI.

This transition might seem like a major disruption, but it represents a positive shift toward risk-based biocompatibility evaluations. For manufacturers that need medical grade silicone sheeting and uncured compound, understanding these updates is essential for maintaining compliance and design integrity. It’s also important to know which standards continue to apply to medical silicones.

Why USP Class VI Is Being Phased Out

USP Class VI was originally published in the 1960s to classify plastics. More specifically, it evaluated materials using broad in vivo animal testing based on worst-case exposure assumptions. Although it became a widely accepted screening tool, USP Class VI was designed as a generalized material-level test. In other words, it wasn’t intended for application-specific device evaluation.   

Today, the phase-out of USP Class VI is driven by three industry shifts:

1. Focus on Application-Specific Risk: A material’s safety depends heavily on its intended use, tissue contact type and contact duration. Short-term fluid transfer tubing presents vastly different biological risks than a long-term implant.
2. Reduction of Animal Testing: Modern material testing frameworks prioritize chemical characterization, toxicological risk assessment, and in vitro methods over generalized animal studies, which also raise concerns about animal welfare and ethics.
3. Evolution of Global Regulatory Expectations: Regulatory bodies, including the FDA and international organizations, require biocompatibility evidence aligned with comprehensive risk management standards. Standalone material designations are no longer enough.

How are USP’s Testing Frameworks Changing?

Accordingly, the United States Pharmacopeia is revising its testing frameworks:

• USP <88> Updates: USP Class designations (Classes I through VI) are being eliminated. Intracutaneous and implantation testing are being removed from USP <88>, which applies to raw plastic and polymer materials intended for medical devices.
• USP <87> Revisions: Cytotoxicity testing remains, but USP <87> is expanding to incorporate broader biological endpoints, such as irritation and genotoxicity evaluations. Lower-sensitivity methods are being phased out in favor of more sensitive test protocols.

For manufacturers of existing medical devices and components, these changes do not mean that USP Class VI is suddenly irrelevant. Historical USP Class VI test data generated prior to these changes remains valid as supporting evidence of material safety. Moreover, “USP Class VI compliant” will probably remain on existing drawings and specifications until those documents are retired.

The Path Forward: ISO 10993 and Application-Driven Safety

The elimination of USP Class VI does not lower safety standards. Instead, it raises them by requiring a more tailored assessment.

For component manufacturers and device designers, the primary framework for evaluating biological safety remains ISO 10993 (Biological evaluation of medical devices). Rather than relying on a one-size-fits-all material label, ISO 10993-1 guides manufacturers through a structured biological risk assessment based on:

• Categorization by body contact (skin, mucosal membrane, circulating blood, etc.)
• Contact duration (limited, prolonged, or permanent)
• Comprehensive chemical characterization and toxicological evaluation

How ElastaPro Supports Your Medical Silicone Needs

At ElastaPro, our medical-grade silicone sheeting and compounds have long met USP Class VI standards. More importantly, our medical silicone formulations are characterized and tested to conform with ISO 10993 requirements. For more information, see our Certification Detail for medical and healthcare silicone sheeting.

Because ISO 10993 and related international benchmarks are not ending, ElastaPro’s customers can transition through these regulatory updates without supply chain disruption or re-engineering delays. We provide the documentation, material consistency, and technical support necessary to satisfy device-level risk assessments.

As conversations shift from “Is this material USP Class VI?” to “How does this silicone perform under ISO 10993 for our specific device exposure?”, ElastaPro is ready to help you navigate material selection with confidence. We offer medical and healthcare silicones in 10, 20, 30, 40, 45, 50, 55, 60, and 70 durometer (Shore A) and supply a full Certificate of Analysis (COA) with every batch.

Contact ElastaPro to discuss your application, or for more information about our capabilities.