Background The most promising aspect of pharmaceuticals and medicine as it relates to nanotechnology is currently drug delivery. In the words of LaVan and Langer: ‘It is likely that the pharmaceutical industry will transition from a paradigm of drug discovery by screening compounds to the purposeful engineering of targeted molecules.’ Reasons Why the Drug Delivery Market is Rapidly Expanding At present, there are 30 main drug delivery products on the market. The total annual income for all of these is approximately US$33 billion with an annual growth of 15% (based on global product revenue). Two major drivers are primarily responsible for this increase in the market. First, present advances in diagnostic technology appear to be outpacing advances in new therapeutic agents. Highly detailed information from a patient is becoming available, thus promoting much more specific use of pharmaceuticals. Second, the acceptance of new drug formulations is expensive and slow, taking up to 15 years to obtain accreditation of new drug formulas with no guarantee of success. How Drug Companies are Reacting to this Expansion In response, some companies are trying to hurry the long clinical phase required in Western medicine. However, powerful incentives remain to investigate new techniques that can more effectively deliver or target existing drugs (Saxl, 2000). In addition, many of these new tools will have foundation in current techniques: a targeted molecule may simply add spatial or temporal resolution to an existing assay. Thus, although many potential applications are envisaged, the actual near future products are not much more than better research tools or aids to diagnosis. These are summarised in the following three tables. Application Areas for Nanoscale Pharmaceuticals and Medicines Medical Diagnostics Table 1. Summary of application areas for nanoscale pharmaceuticals and medicine in diagnostics. | | | | | | Diagnostics | | Nanosized markers, i.e. the attachment of nanoparticles to molecules of interest. | Minute quantities of a substance can be detected, down to individual molecules. | E.g. detection of cancer cells to allow early treatment. | ? | | ‘Lab-on-a-chip’ technologies | Miniaturisation and speeding up of the analytical process. | The creation of miniature, portable diagnostic laboratories for uses in the food, pharmaceutical and chemical industries; in disease prevention and control; and in environmental monitoring. | Although chips currently cost over £125 (US$2085) each to make, within three years the costs should fall dramatically, making these tools widely available. | | Quantum dots. | Quantum dots can be tracked very precisely when molecules are ‘bar coded’ by their unique light spectrum. | Diagnosis. | In early stage of development, but there is enough interest here for some commercialization | Drug Delivery Systems Table 2. Summary of application areas for nanoscale pharmaceuticals and medicine in drug delivery. | | | | | | Drug delivery | | Nanoparticles in the range of 50–100 nm. | Larger particles cannot enter tumour pores while nanoparticles can easily move into a tumour. | Cancer treatment. | ? | | Nanosizing in the range of 100–200 nm. | Low solubility. | More effective treatment with existing drugs. | ? | | Polymers. | These molecules can be engineered to a high degree of accuracy. | Nanobiological drug carrying devices. | ? | | Ligands on a nanoparticle surface. | These molecules can be engineered to a high degree of accuracy. | The ligand target receptors can recognise damaged tissue, attach to it and release a therapeutic drug. | ? | | Nanocapsules. | Evading body’s immune system whilst directing a therapeutic agent to the desired site. | A Buckyball-based AIDS treatment is just about to enter clinical trials. | Early clinical. | | Increased particle adhesion. | Degree of localised drug retention increased. | Slow drug release. | ? | | Nanoporous materials. | Evading body’s immune system whilst directing a therapeutic agent to the desired site. | When coupled to sensors, drug-delivering implants could be developed. | Pre-clinical: an insulin- delivery system is being tested in mice. | | ‘Pharmacy-on-a-chip’ | Monitor conditions and act as an artificial means of regulating and maintaining the body’s own hormonal balance. | E.g. diabetes treatment. | More distant than ‘lab-on- a-chip’ technologies. | | Sorting biomolecules. | Nanopores and membranes are capable of sorting, for example, left- and right-handed versions of molecules. | Gene analysis and sequencing. | Current - ? | Tissue Regeneration, Growth and Repair Table 3. Summary of application areas for nanoscale pharmaceuticals and medicine in tissue regeneration, growth and repair. | | | | | | Tissue regeneration, growth and repair | | Nanoengineered prosthetics. | Increased miniaturisation; increased prosthetic strength and weight reduction; improved biocompatibility. | Retinal, auditory, spinal and cranial implants. | Most immediate will be external tissue grafts; dental and bone replacements; internal tissue implants. | | Cellular manipulation. | Manipulation and coercion of cellular systems. | Persuasion of lost nerve tissue to grow; growth of body parts. | More distant: 5-7 years. | |
