Nanotechnology and the Quest for the Ultimate Drug-Delivery System - Pharmaceutical Technology

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Nanotechnology and the Quest for the Ultimate Drug-Delivery System


Pharmaceutical Technology


The popularity of Drexler's ideas should have made the fear of runaway nanobots a public issue more than a scientific problem, but statements by prominent scientists in support of this doomsday vision has all but killed Feynman and Drexler's ideal for molecular nanotechnology and the promises it holds for repairing human cells and extending lifespans. For example, Sun Microsystems Co-founder Bill Joy wrote in a landmark Wired magazine essay in 2000, "Why the Future Doesn't Need Us," that "An immediate consequence of the Faustian bargain in obtaining the great power of nanotechnology is that we run a grave risk—the risk that we might destroy the biosphere on which all life depends."

Another attack came from Richard Smalley, Rice University's 1996 Nobel Laureate in chemistry. At first, he supported the benefits of a world in which "We learn to build things at the ultimate level of control, one atom at a time." In 2001, he changed his mind when he said in a Scientific American article that, "such control wouldn't really be possible because the fingers we'd need to handle such a delicate task are too big."

So where does this leave nanotechnology? Perhaps the most widely accepted definition of nanotechnology to date appears on NASA's website: "The creation of functional materials, devices and systems through control of matter on the nanometer length scale (1–100 nanometers), and exploitation of novel phenomena and properties (physical, chemical, biological) at that length scale." This definition seems to claim that nanotechnology is still an immature technology that for the most part refers to research into systems at the scale of 100 nm or less using known experimental techniques. In other words, although there has been a lot of buzz about advances in nanotechnology, an awful lot of the "breakthroughs" seem to simply be about taking anything "small" that sounds like science fiction and building up some buzz around it.

This is especially true for nanotechnology as it deals with drug delivery where many of the current "nano" drug- delivery systems evolved from known drug-delivery systems that happen to be in the nanometer range such as liposomes, polymeric micelles, nanoparticles, dendrimers, and nanocrystals. In a 2007 editorial in the Journal of Controlled Release, Kinam Park, a Showalter Distinguished Professor of biomedical engineering and professor of pharmaceutics at Purdue University, criticized this approach when he wrote: "In drug delivery, however, describing nanotechnology based on a size limit is pointless because the efficiency and usefulness of drug-delivery systems are not based only on their sizes."

What then are the properties of the ideal drug-delivery system developed by nanotechnology? The answer is the same properties that would make a drug-delivery system developed by any technology ideal. These properties were best described by Joseph R. Robinson, a pioneer in the development of controlled-release drug-delivery systems. In the 1996 edition of Modern Pharmaceutics, he wrote, "If one were to imagine the ideal drug-delivery system, two prerequisites would be required. First, it would be a single dose for the duration of a treatment, whether it be for days or weeks, as with infection, or for the lifetime of the patient, as in hypertension or diabetes. Second, it should deliver the active entity directly to the site of action, thereby minimizing or eliminating side effects." Sadly, such a drug-delivery system still does not exist. The truth is that even after four decades of trying, an effective site-specific drug-delivery system has not yet been developed showing how elusive the ideal drug-delivery system still is.

So what is the future of nanotechnology and especially the future of nanotechnology for drug delivery? In December 2007, NNI released a new strategic plan with four key goals: advance a world-class nanotechnology research and development process; foster the transfer of new technologies into products for commercial and public benefits; develop and sustain educational resources, a skilled workforce, and the supporting infrastructure and tools to advance technology; and support responsible developments of nanotechnology.

In a letter accompanying the strategic plan, White House Science Adviser John H. Marburger III commented, "With the implementation of this plan, the United States will remain at the forefront of nanoscale science and engineering and a leader in achieving the economic benefits offered by the emerging technology."


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