26 October 2023

Substance-based Medical Devices are specifically regulated by the MDR (EU) 2017/745, starting with the classification in Rule 21 of Anx. VIII up to the introduction of hybrid testing – where one element is a drug – to prove the conformity of these products. To ensure you have all the most important information, read the answers to 3 of the most frequently asked questions.

  1. What is a substance-based medical device?

Substance-based Medical Devices are those products that consist of a substance, permitted in a medical device, whose main action is not carried out by pharmacological, immunological or metabolic means, but may be assisted by such means.

Substances that cannot be contained in a medical device include, for example:

  • vital biological material or living organisms, including living microorganisms, bacteria, fungi and viruses;
  • viable animal tissues and cells or their derivatives;
  • viable human tissues and cells or their derivatives.
  1. What does a substance-based device with an ancillary drug mean?

Substance-based Medical Devices with an ancillary function are those devices, consisting of substances that incorporate as an integral part an element that, if used separately, would be considered a medicine. The latter performs an ancillary action in or on the human body or its components and supports the medical device in achieving its specific medical purpose. The classification of these devices depends on applying rule 21 of the Anx. VIII of the MDR Regulation (EU) 2017/745.

Devices referring to Rule 21 are, in particular, those composed of substances or combinations of substances intended to be introduced into the human body through a body orifice or to be applied to the skin, and which are absorbed or locally dispersed in the human body.

  1. What is the mechanism of action?

The mechanism of action, in general, describes how a product interacts with the structures of the human body with which it comes into contact and differs depending on whether it is a medical device or a drug.

The mechanism of action in Medical Devices must only be mechanical, physical or chemical, whereas drugs only have pharmacological, metabolic or immunological mechanisms.

*** Medical Device

  • Mechanical effect: refers to an interaction of a substance with structures in the body, such that it involves only a protective mechanism.
  • Physical effect: refers to an interaction of a substance with other substances present in the body extracellularly, such that it only transforms the surrounding environment/matter.
  • Chemical effect: refers to an interaction of a substance with other substances present in the body extracellularly such that the initial chemical substances (the reactants) are transformed into different chemical substances (the products of the reaction) through the formation of different bonds between the atoms.

*** Drug

  • Pharmacological effect: refers to an interaction at the molecular level between a drug and a constituent of the human body (e.g. cells, components of the extracellular matrix, blood or body fluids) that results in the initiation, enhancement, reduction or blockage of physiological functions or pathological processes.
  • Immunological effect: refers to an action initiated by a drug on the human body and mediated by cells or molecules involved in the functioning of the immune system, such as cytokines, antibodies and lymphocytes.
  • Metabolic effect: refers to the action of a drug that causes an alteration in the extent or nature of a biochemical, physiological or pathological process affecting a function of the human body.

As regards substance-based Medical Devices with an ancillary drug, the main intended action must not be achieved by pharmacological means. The drug incorporated in the medical device must have a supporting, ancillary function to the intended use of the medical device that is achieved by mechanical, physical or chemical means.

To demonstrate the mechanism of action of the substance-based medical device and the ancillary function of the drug it contains, dedicated tests must be carried out.

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