Carbon nanotubes for drug delivery applications

During the last years, pharmaceutical companies have been facing the challenge of developing new molecules to replace the existing ones in order to sustain their core business. This became a very expensive, time-consuming and frustrating task. It is now being realized that an alternative to drug development is to reuse the existing drugs by changing their pharmacokinetic or pharmacodynamic properties thanks to their incorporation to drug carriers. The so-called drug delivery systems hold promise to optimize drug absorption, distribution, metabolism and excretion (pharmacokinetics), and ultimately to improve the clinical effi cacy of pharmacotherapies. In the last 20 years with the advent of micro- and nano-technologies, a variety of micro- and nano-devices including nanostructures have been developed for their application as drug delivery systems. Among them, carbon nanotubes, carbon fi bers with a few nanometers in diameter and several microns length, have called the attention of the scientifi c community due to their large surface area, high aspect ratio and their extraordinary mechanical and electrical properties. Carbon nanotubes are produced by different methods, including chemical vapor deposition, laser ablation and arc discharge. Carbon nanotubes have been investigated for applications ranging from cancer therapy to gene therapy and small interfering ribonucleic acid delivery. However, a serious concern is the potential toxicity of carbon nanotubes as has been shown in vitro and in vivo. Ultimately, a balance between benefi ts and risks will dictate whether carbon nanotube-based drug delivery systems will reach the market in the years to come.