Key parameters for encapsulating drugs in nanoparticles

Oct 2 2006

One of the early, successful uses of nanoparticles has been to develop delivery vehicles capable of ferrying large amounts of water-insoluble drugs to tumors.

Abraxane, for example, uses albumin nanoparticles to deliver high concentrations of paclitaxel to breast tumors, eliminating the use of the solvent mixture that itself can be toxic enough to limit the utility of this powerful anticancer agent. As a result, patients treated with Abraxane suffer fewer side effects and improved outcomes compared to those who receive other formulations of paclitaxel.

As a means of helping researchers develop nanoparticle-based formulations of water-insoluble drugs, investigators at the University of Texas at Austin have conducted a systematic study to quantify some of the key parameters involved in forming stable nanoparticles containing maximum levels of water-insoluble drug molecules. The findings from these experiments have been published in the journal Langmuir.

Robert Williams III, Ph.D., led this study of how water-insoluble drugs become incorporated into nanoparticles. Using a variety of chemical, temperature, and mixing conditions, the investigators create nanoparticles in which drug molecules account for as much as 86% of the final weight of the drug-nanoparticle combination.

Over the course of these experiments, the researchers found, for example that slowing the formation of the nanoparticles themselves had a large, positive effect on final drug loading levels. Mixing energy also had a large effect, as did the addition of polymer stabilizers, which led to the production of smaller nanoparticles. In addition to generating experimental data that may help guide future nanoparticle drug delivery vehicles, the researchers also provide mechanistic insights that may also prove useful.

This work is detailed in a paper titled, “Drug nanoparticles by antisolvent precipitation: mixing energy versus surfactant stabilization.” This paper was published online in advance of print publication. An abstract of this paper is available at the journal’s website. View abstract.