Device Safety Eval

Introduction to Safety Evaluation of Pharmaceuticals and Medical Devices

  • The regulatory frameworks for nonclinical safety assessment requirements for medical devices have achieved a level of global harmonization, especially in biocompatibility evaluation.

  • The ISO 10993 standards serve as the primary guidance for the USA, EU, Japan, and associated countries. Specific regulations are cited only in special instances.

  • The global trend indicates a preference for adherence to the International Standards Organization (ISO) guidelines for supporting regulatory submissions.

Regulatory Definition of Medical Devices

Definition in the USA

  • According to Section 201(h) of the Food, Drug, and Cosmetic Act:

    • A medical device is defined as an instrument, apparatus, implement, machine, contrivance, implant, in vitro reagent, or any other similar or related article, including a component, part, or accessory, that:

    • Is recognized in the official National Formulary (NF) or the United States Pharmacopeia (USP) or any supplement to them.

    • Is intended for use in diagnosing disease or other conditions, or in curing, mitigating, treating, or preventing disease in humans or animals.

    • Affects the structure or function of the body and does not rely on chemical action within or on the body to achieve its primary intended purposes.

  • Reference: CDRH 1992

Nonclinical Testing Requirements

Key Guidance from USP

  • The initial guidance regarding nonclinical testing for devices originated from the United States Pharmacopeia (USP).

Application in Diagnostics

  • Devices such as in vitro diagnostics, which analyze samples collected from patients (e.g., plasma, blood, urine), are regulated as medical devices but do not necessitate safety evaluations as they do not have patient contact.

  • Imaging devices (X-rays, MRI, CAT scans) operating externally to the body also do not require nonclinical biocompatibility assessment if there is no actual contact.

International Standards Organization (ISO)

Biocompatibility Evaluation

  • The essential guidance for biocompatibility evaluation largely comes from ISO, a non-governmental organization (NGO).

  • The relevant ISO document is ISO 10993-1:1997, titled "Biological evaluation of medical devices – Part 1: Evaluation and Testing."

  • This document outlines the requirements for determining the nature of patient body contact with the device, categorized into:

    • Surface Devices: Includes skin contact, mucous membrane interaction, and breached surfaces.

    • External Communicating Devices: Engages with various blood pathways (both direct and indirect).

    • Implant Devices: Engages with bone/tissue and blood.

  • The cumulative contact duration is characterized as:

    • Limited exposure (<24 hours)

    • Prolonged exposure (24 hours to 30 days)

    • Permanent contact (>30 days)

Additional ISO Guidelines (Post-2002)

  • New guidances (parts 13-20) developed by ISO relate to chemical and analytical evaluations, including requirements for immunotoxicity testing.

  • Complete list of ISO standards (as of November 2007) includes:

    • Part 1: Evaluation and testing

    • Part 2: Animal welfare requirements

    • Part 3: Genotoxicity, carcinogenicity, reproductive toxicity tests

    • Part 4: Tests for interactions with blood

    • Part 5: In vitro cytotoxicity tests

    • Part 6: Tests for local effects after implantation

    • Part 7: Ethylene oxide sterilization residuals

    • Part 8: Withdrawn

    • Part 9: Identification and quantification of degradation products

    • Part 10: Tests for irritation and sensitization

    • Part 11: Tests for systemic toxicity

    • Part 12: Sample preparation and reference materials

    • Part 13: Identification of degradation products from polymers

    • Part 14: Identification of degradation products from ceramics

    • Part 15: Identification of degradation products from metals and alloys

    • Part 16: Toxicokinetic study design for degradation products and leachables

    • Part 17: Establishing allowable limits for leachables

    • Part 18: Chemical characterization of materials

    • Part 19: Physicochemical, mechanical, and morphological characterization

    • Part 20: Principles and methods for immunotoxicology testing of medical devices

USFDA Regulations for Medical Devices

Relevant Legislation

  • FDA's regulation of medical devices is governed by five key statutes:

    • Food Drug and Cosmetic Act (FDCA) of 1938

    • Medical Device Amendments (to FDCA) of 1976

    • Safe Medical Devices Act of 1990

    • Medical Device Amendments (to FDCA) of 1992

    • Medical Device User Fee and Modernization Act of 2002

Compliance with ISO Standards

  • Although the FDA generally accepts the ISO 10993 standards for safety testing, it possesses its own guidance (G95-1) that may alter testing requirements.

  • This guidance necessitates individual organ/system toxicity evaluation and additional considerations for devices with leachables or absorption materials.

Specific Points of Clarification

  • For devices that might release dangerous leachables, pharmacokinetics testing may be required.

  • Reproductive/developmental toxicity tests may be imposed depending on the materials employed.

  • Long-term biological tests may be warranted based on the nature and mobility of the device materials.

Testing Matrix for Implantable Devices

  • Table 37 outlines the typical test matrix for an implantable device, detailing necessary evaluations against ISO guidelines.

Testing Requirements and Evaluation Protocols

Initial and Supplementary Evaluation Tests

  • Full evaluation criteria based on the biological effects and duration of body contact are organized in Tables 34 and 35, summarizing initial and supplementary evaluation testing protocols categorized based on device type and biological effect.

Topical Devices Overview

  • Topical devices mainly refer to systems that deliver drugs (e.g., transdermal patches) and wound dressings:

    • Test requirements are summarized in Table 38.

Regulatory Compliance and Global Testing Requirements

FDA Device Categories and Suggested Testing

  • Summary of biological tests by device category based on required exposure duration is provided in Tables 36, 38, and 39, mapping out biological tests pertinent to both short term and long term contact evaluations.

Japan's Regulatory Framework

  • Japan’s biological studies for medical device approval are dictated by Notification No. 99 (“YAKURI”), updated in February 2003 with Notification No. 0213001 (“IYAKUSHIN”), which aligns itself with ISO 10993 guidelines.

Additional Global Regulatory Authorities

  • A summary of international device regulatory authorities and their respective websites is presented in Table 41. This section encapsulates essential resources for understanding global regulatory frameworks and tests relevant to biocompatibility evaluations.

Conclusion and Ethical Implications

  • Throughout the development and market introduction of medical devices, the implications of patient safety, biocompatibility, and regulatory compliance play a pivotal role, underscoring the need for thorough testing and evaluation aligned with established international standards.

References

  • Provides a comprehensive reference list that outlines various guidelines, frameworks, and methodologies related to medical device safety evaluation and regulatory communications.

  • A detailed exploration of research projects and further required readings aligns with the proper application of scientific and regulatory standards for medical devices seeking approval in global markets.

Similarities between the development of medical devices and drugs include:

  • Both require rigorous testing to ensure safety and efficacy before regulatory approval.

  • They must comply with strict regulatory frameworks, which may involve similar standards and guidelines, such as those outlined by the FDA or ISO.

  • The process involves multiple phases, including preclinical and clinical evaluations.

Differences include:

  • Development timelines: Drug development often takes longer due to complex clinical trials required for pharmacokinetics and pharmacodynamics, while some medical devices can be developed and approved faster.

  • Types of testing: Drugs usually undergo extensive pharmacological testing, while medical devices may focus more on biocompatibility and physical tests.

  • Regulatory pathways: Medical devices may have a more tiered regulatory process (Class I, II, or III), whereas drugs follow a more uniform pathway, including extensive Phase I-III clinical trials.

In the FDA regulation of medical devices, devices are categorized into three classes based on the level of control necessary to ensure the safety and effectiveness of the device:

  1. Class I

    • These devices are considered low-risk and subject to the least regulatory control.

    • Most Class I devices are exempt from the premarket notification requirement (510(k)).

    • Examples include bandages, handheld surgical instruments, and tongue depressors.

  2. Class II

    • These devices are moderate-risk and generally require premarket notification to demonstrate that they are substantially equivalent to a legally marketed device.

    • Special controls may also be applied, which can include performance standards and post-market surveillance.

    • Examples include infusion pumps, surgical drapes, and x-ray machines.

  3. Class III

    • Class III devices are high-risk and require premarket approval (PMA), showing that they are safe and effective through extensive clinical trials.

    • This class includes devices that support or sustain human life, are of paramount importance for health, or present a potential unreasonable risk of illness or injury.

    • Examples include pacemakers, heart valves, and breast implants.