Abstract

Nanotechnologies have gained substantial interest in pharmaceutical sciences and also for the pharmaceutical industry during the last decade. New nano-scale drug delivery approaches have helped to cure diseases in a better way than before.
Oral nanocrystal formulations with particle sizes in the submicron range (a few 100 nm) developed for several poorly water soluble drugs during the past decade were brought successfully to the market. These products are characterized by dissolution rate limited absorption and manufactured by top-down milling technologies.
In contrast to non-oxidized multi-walled carbonanotubes (MWCNTs), clay mineral nanotubes are naturally occurring biocompatible, multi-walled nano-containers, having found recently broad interest in multiple technical fields, e.g.for self-repairing anticorrosion coatings, conductive and paramagnetic coatings, as biomimetic nanoreactors for bone tissue regeneration etc. and more recently also in classical pharmaceutical fields like taste masking and sustained drug release applications.
The article gives an overview about oral nanocrystal products and tries to capture current trends in the field of pharmaceutical applications of nanotubes .

INTRODUCTION

During the last decade a dramatic increase of scientific and public interest in the field of nanotechnology (a term that was firstly used by Norio Taniguchi in 1974) has led to controversy regarding potential implications and risks but also to significant progress. From a physical standpoint dimensions between 1 and 100 nanometer would be considered as `nanoparticles`. This range can be broader in pharmaceutical sciences going up to rather submicron particles with diameters of a few hundred nanometers. If nanoparticles are by approximately 100 % composed of drug, the terminus `nanocrystals` is also used in opposite to polymeric `nanoparticles`. Dispersions of nanocrystals are then called `nanosuspensions` (in contract to `macrosuspensions`).
Since the late nineties drug delivery strategies have focused on an increasing number of poorly water soluble and lipophilic drugs in early drug development. To formulate these typically requires to make use of non-conventional formulation technologies, e.g.

• Salt formation, 
• Cyclodextrins based complexation, 
• Lipid formulations (SMEDDS, SEDDS systems)
...