When dealing with medical devices with coatings, the regulatory pathway can be nuanced. The presence of a coating may impact the classification of the device and lead to additional requirements. To determine the correct regulatory pathway and applicable requirements, it’s important to clarify the nature of the coating material and its intended purpose.
A key consideration is whether the coating material is classified as a medicinal substance. If a medicinal substance is used in the coating and its action is ancillary to that of the device, the device is classified as Class III according to Rule 14 of the MDR. This classification necessitates a consultation procedure with the medicinal products authority, as outlined in Annex IX, Section 5.2 of the MDR. For such coating materials, a CTD dossier must be prepared for the substance, in addition to meeting other MDR requirements. Typical examples include catheters coated with heparin or antibiotics.
Conversely, as indicated in MDCG 2022-5, the use of a chemical coating does not automatically mean the substance is classified as a medicinal product. For instance, hydroxyapatite, commonly used as a coating for orthopedic and dental implants, as well as hydromer and phosphorylcholine coatings are not considered to be medicinal products. In these cases, if the device is implantable and intended for long-term surgical use (more than 30 days), it typically falls under Rule 8 of the MDR. When applying this rule, it is essential to clarify whether the coating is intended to have biological effects and whether the device is considered bioactive due to the presence of the coating. For instance, adhesives and implantable devices claimed to be bioactive through the attachment of surface coatings such as phosphorylcholine will be classified as Class III. However, if no biological effect is claimed, a lower class of risk may apply. In these cases, the coating may serve a mechanical or protective function, such as improving device durability or preventing surface contamination without biological interaction.
Additionally, special Rule 19 applies to medical devices if their coating contains nanomaterials. To determine the class of risk according to this rule, each device must be assessed based on its specific characteristics, with particular attention to the potential release of free nanoparticles. For example, intravascular catheters made from non-degradable polymer with nanocoating are classified as Class III if they present a high or medium potential for exposure to the human body. Conversely, a solution administration set made from non-degradable polymer with nanomaterials embedded in the polymer matrix, presenting a low exposure risk, may be classified as Class IIb.
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