Carbon nanotubes as functional excipients for nanomedicines: I. Pharmaceutical properties.

Carbon nanotubes (CNTs) are considered potential biomedical materials because of their flexible structure and propensity for chemical functionalization. In the first part of this two-part review we focus on the properties and use of CNTs as building blocks for novel drug delivery systems, dosage forms, and biomedical substrates. Pharmaceutical excipients have been regarded as inert or nonactive components of dosage forms, but they are essential and necessary components of pharmaceutical preparations. Here we present a collection of data to initiate the description of CNTs as pharmaceutical excipients. We summarize the synthesis, purification, and analysis of CNTs related to their pharmaceutical properties and quality control. Application of CNTs in biological systems depends on their compatibility with hydrophilic environments; therefore, the solubilization of CNTs in pharmaceutical solvents is essential. Furthermore, because it is becoming increasingly important that the relevant chemical, physiochemical, and pharmaceutical properties of CNTs be identified, we have prepared a "mini-monograph" of CNTs that compiles their pertinent properties.