Editorial Feature

Nanotechnology and Drug Delivery - Opportunities for Nanotechnology in Drug Delivery

Nanotechnology is widely regarded as one of the most important sources of new technology over coming decades and its development will impact upon a broad range of industries and end-users. However, there are also ethical, legal, policy and social issues that need to be considered if the potential benefits of nanotechnology are to be realised in a safe and effective way.

Opportunities for Nanotechnology in Drug Delivery

Within the biomedical industry, especially the medical device and diagnostic areas, drug delivery methods that use the enabling technology of nanotechnology and biomaterial in optical devices are emerging strengths for Australian practitioners.

Vast majority of drug therapies currently affect entire body. Small but significant number of cancer patients die from complications arising from toxic effects of chemotherapy and radiation therapy. In biopharmaceutical delivery there are a number of features of nanotechnology which make it a suitable tool to address major issues:

  • reduction of particle size and increased surface area, enhancing solubility
  • increasing oral bioavailability
  • targeting of tissues, cells and cellular receptors
  • gene and vaccine delivery
  • allows crossing of biological membranes especially the blood brain barrier
  • Encapsulating drugs in a variety of nanoscale carriers, such as carbon nanotubes or some other molecule
  • Applying drug-eluding coatings to internal medical devices (e.g. pacemakers) that can be "switched on and off" through nanomagnetics to allow drug molecules to be diffused into the body
  • Using nanoparticles to enter damaged cells and release enzymes that either initiate cell repair or the cells' auto destruct sequence, known as "apoptosis"
  • Providing better performance through nanoparticules (e.g. pain reliever Aleve)
  • Using nanoporous membranes to control timerelease delivery of drug molecules, allowing constant rate of diffusion
  • Adding specific nanoreceptors to drug surfaces to release therapeutic drugs exactly where needed

A market analysis performed in March 2004 suggested that "Nanotechnology is currently applied in ~1% of drug delivery technologies under development; by 2015, ~14% of drug delivery technologies may use nanotechnology".

Pulmonary Drug Delivery

There has been growing interest in the potential for the systematic delivery of drugs and therapeutic agents (e.g. peptides and proteins) via pulmonary (inhalation) means. Pulmonary drug delivery is an attractive option compared to oral administration or other invasive delivery techniques.

Pulmonary drug delivery based on Surface Acoustic Wave (SAW) technology allows fluids to be atomised as precisely controlled droplets. When the device is activated, an electric field is applied to the surface of the electrode, producing an acoustic wave. The drug is introduced to the electrode in the form of a liquid droplet and atomisation occurs, producing micro or nanoparticles, which remain as a liquid. The size of the particles can be well-controlled by the electrode design and also the properties of the electric field.

These nanoparticles can then be inhaled into the lungs, where they are directed across the pulmonary alveoli and absorbed into the bloodstream. This allows for increased efficacy of inhaled insulin compared to injected insulin, due to faster uptake and clearance.

Pulmonary delivery is particularly attractive for a number of frequent-application drugs such as insulin for diabetics who need to inject on a daily basis. Other advantages include the pain-free delivery of medication in a non-invasive manner, administration of large and small molecule drugs, and the ability to tightly control drug dosage. In addition, the technology can be packaged in a consumer-friendly compact personal inhaler, with the benefit of increasing patient compliance.

Transdermal Delivery

Transdermal Delivery involves the painless delivery of large bio-pharmaceutical molecules across the essentially impervious outer layer of the skin through skin contact with topologically undulating patches such as MicroArray Patchs. MicroArray Patchs provide an effective and pain-free delivery system for; large molecules such as DNA, vaccines, proteins/peptides, drugs and hormones. Ultimately, the MicroArray Patchs could be used by non-specialized personnel, such as health care professionals, farm workers, animal owners or general.

MicroArray Patchs consist of arrays of solid micro-protrusions made from biocompatible and/or biodegradable polymers. The reagents for delivery are attached to the external surface of the MicroArray Patchs, integrated into the polymer or both. When the patch is applied, the microneedles cross the stratum corneum and penetrate into the epidermis. The microneedles do not penetrate deep enough to enter blood capillaries or nerves, hence the delivery is non-invasive and pain-free.

The MicroArray Patchs provide direct access to the cells of the immune system, hence their potential in vaccination. Transdermal delivery enables drugs to be delivered systemically, bypassing the gastrointestinal tract and the first pass metabolism of the drug in the liver. Since liver metabolism is avoided, lower doses of drug can be used and liver toxicity can be reduced.

MicroArray Patchs steadily release the drug over a prolonged period of time, generating steady-state blood levels and decreasing dosage peaks and troughs, which minimizes "break-through" events, increases efficacy, and decreases the incidence and frequency of side effects. MicroArray Patchs are ideal for drugs with short half-lives, those too potent to be administered orally or those that are not tolerated by inhalation.

MicroArray Patchs are easier to use than traditional drug delivery systems. The patches eliminate the pain and trauma associated with needles and also reduce the risk of infection. Delivery from the patches is short term as the micro-protrusions are naturally shed from the skin within three weeks.

This content was provided by NanoVic (Nanotechnology Victoria)

Copyright Nanotechnology Victoria, AZoNano.com

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