Nanoparticles and drugs

Since the early 1970s, and exponentially since the 2000s, the development of nanoparticles has been a rapidly expanding field for biomedical applications, particularly in cancer treatment and diagnostics. Their remarkable properties (optical, physical, thermal, chemical, etc.) enable these nano-objects to be used as vectors and/or for diagnostic purposes, but also as medicines in their own right. The ease and freedom with which they can be synthesized and functionalized with molecules, especially active substances, has led to the creation of a large and diversified catalog of pharmaceutical nanoparticle objects.

Numerous types of nanoparticles have been used or are currently undergoing preclinical or clinical evaluation. Whether organic or inorganic, these nano-objects can be found in colloidal form (suspended in a solvent) or immobilized on surfaces. This has enabled them to be used both as drugs and in medical devices.

The nanoscale is of interest in the pharmaceutical field because of the remarkable properties of nano-objects, such as :

• a very large specific surface area, enabling the formation of large reservoirs of active ingredients;

• a size suited to the passage of barriers (skin, blood-brain barrier, intestinal barrier, feto-placental barrier, etc.), with the associated risks (toxicity, dissemination, etc.);

• the ability to target the area to be treated.

Nanoparticles as drugs must be subject to the same international regulations as any other drug currently on the market. Current control methods for nano-objects are mainly derived from the materials sector, and are still insufficiently adapted to the pharmaceutical field. Indeed, the determination of purity (main substance content) and impurities (degradation, synthesis intermediates, residual solvents, etc.) remains poorly defined.

In this article, after introducing a few basic concepts to help readers better understand the field of nanoparticles, an overview will be given of the drugs and medical devices on the market and in development. This will be followed by a look at the control of conventional drugs, before focusing on the regulations and controls that would be most appropriate for nanoparticles used as drugs. This article discusses methods for characterizing and controlling nanoparticles as pharmaceutical ingredients. The regulation of medical devices will not be covered in this dossier.

The difficulties created by the nanoscale in the control and monitoring of nano-objects will be discussed. The final section will look at the benefit/risk balance of these objects, in the light of scientific, technological and clinical...