If your drug use consists of an occasional aspirin, you may not see the need for serious work on drug delivery. But if you were diabetic, having to inject insulin several times a day, or a cancer patient experiencing debilitating side effects from your treatment, the benefits of improved drug delivery could change your life.
Perhaps the most publicized use of nanotechnology in drug delivery under development is the use of nanoparticles to deliver drugs to cancer cells. However, that’s just the tip of the drug delivery iceberg: there are a number of other ways that nanotechnology can make the delivery of drugs more efficient and potentially less unpleasant for the patient.
Several companies and universities are working on developing nanoparticles that seek out cancer cells and destroy them while causing minimal harm to healthy cells. NanoBioDrug from Nanobiotix are nanoparticles with molecules on the surface that are attracted to certain types of diseased cells. Researchers at Harvard Medical School have shown that nanoparticles with a particular RNA strand on their surface are attracted by prostate cancer cells, for example. Once the nanoparticles are concentrated in the diseased cells, the material in the core of the nanoparticle is activated by a signal which could be delivered by an MRI, ultrasound, or laser light.
The mechanism of killing the diseased cell varies. For example, if the magnetic signal from an MRI is used with a nanoparticle whose core is iron oxide, the magnetic signal moves each nanoparticle and physically stirs up the insides of the cell, thereby destroying it. If an ultrasound signal is used, the core of the nanoparticle could contain chemicals that are released by the signal. At this point in time, studies of the effectiveness of NanoBioDrugs on cancer in large animals are currently underway.
Many drugs are injected, rather than being taken in pill form, because they can be destroyed by acids in the stomach. BioDelivery Sciences International has developed a method whereby drug molecules are contained in particles called nanocochleate. These particles protect the drug from stomach acid. When the nanocochleate particles reach the blood stream, they fuse with cells, releasing the drug into one cell and then heading off to do the same with other cells.
BioDelivery is conducting pre-clinical studies of the first drug to use this method, a fungal infection-fighting drug that is currently delivered by injection. In similar work a university in Taiwan, the National Tsing Hua University, has been successful in delivering insulin in studies with laboratory rats. The insulin molecule is encapsulated in nanospheres made from a polymer called chitosan, and delivered orally. If all goes well, this pill form of insulin will be a godsend to millions of diabetics worldwide.
But what about the holy grail of medical breakthroughs, preventing the common cold? NanoBio Corporation may just have found a way to use nano-sized antimicrobial droplets, called nanoemulsions, to head your next cold off at the pass. The key to helping you avoid catching a cold or the flu is the longevity of the nanoemulsions; they can stay in your respiratory tract for several hours and continue to kill viruses while having no discernable side-effects. If you, like me, dislike hanging out in groups during cold or flu season, keep a watch on this research and hope it gets into clinical trials and through the approval process soon.
NanoBio and the University of Michigan are also developing a variety of vaccines that use nanoemulsions. These vaccines would be applied with a nasal swab rather than by injection, and would not require refrigeration.
Novavax, Inc. encapsulates drugs in emulsion nanoparticles (called micellar nano particles) that transport a drug through the skin. You spread the emulsion on your skin like a lotion. This method avoids passing the drug through your stomach with associated side effects. The emulsion provides a reservoir of the drug just under the surface of your skin from which the drug can continue to spread into your bloodstream, maintaining stable levels of the drug over time.
An estrogen replacement therapy lotion using micellar nano particles is already on the market and a testosterone therapy lotion is under development. Novavax now seems to be focused on vaccines and is licensing the micellar nano particles technology. The technique may eventually be used across a range of products such as hormones, pain killers, and allergy relief.
pSivida Limited has a drug delivery product called BioSilicon. This is a silicon particle riddled with nano-sized pores. The drug to be delivered is loaded into the pores and as the silicon particle dissolves, the drug is released. pSivida can customize the size and porosity of silicon particles to control the time it takes them to dissolve. BioSilicon may be used in implants under the skin that could release a drug over days, weeks or months.