Nanomedicine is yielding new and improved treatments and diagnostics for a range of diseases and disorders. Nanomedicine applications incorporate materials and components with nanoscale dimensions where novel physiochemical properties emerge as a result of size-dependent phenomena and high surface-to-mass ratio. Nanotherapeutics and in vivo nanodiagnostics are a subset of nanomedicine products that enter the human body. These include drugs, biological products, implantable medical devices, and combination products that are designed to function in the body in ways unachievable at larger scales. (...) Nanotherapeutics andin vivonanodiagnostics incorporate materials that are engineered at the nanoscale to express novel properties that are medicinally useful. These nanomedicine applications can also contain nanomaterials that are biologically active, producing interactions that depend on biological triggers. Examples include nanoscale formulations of insoluble drugs to improve bioavailability and pharmacokinetics, drugs encapsulated in hollow nanoparticles with the ability to target and cross cellular and tissue membranes and to release their payload at a specific time or location, imaging agents that demonstrate novel optical properties to aid in locating micrometastases, and antimicrobial and drug-eluting components or coatings of implantable medical devices such as stents. (shrink)

Unlike drugs and medical devices, for which long standing and continuously improving quality assurance/quality control infrastructures exist, many nano-based products lack well-defined standards that are useful to manufacturers and regulators. Inherent variabilities in nanoparticle sizes and shapes, their large surface-to-volume ratios, and their mesoscale interactions with subcellular structures, suggest new complexities and challenges that must be met before widespread application of nanomedicines can be expected.

In prominent funding and policy statements, a particle with at least one dimension in the 1-300 nm size range must have novel physicochemical properties to count as a “nanoparticle.” Size is thus only one factor. Novelty of a particle's properties is also essential to its “nano” classification. When particles in this size range are introduced into living systems, they often interact with their host in novel ways that require some modification of existing methods and models used by pharmaceutical scientists and (...) toxicologists for assessing their efficacy and safety. It is not clear, however, whether the novelty of the intended physicochemical properties is in any way related to the novel behavior of those particles when their toxicity is evaluated. In fact, when considering toxicity, much of the concern about nanoparticles relates to the unanticipated or poorly understood interactions. (shrink)