Transdermal Micro-needle Drug Delivery System

Science | August 3, 2010 | Share

We are all familiar with the œnicotine patches that ex-smokers use in order to gradually reduce their dependence on nicotine. These patches are scientifically known as Transdermal Drug Delivery Patches. They deliver drugs to the body through the skin. Since the skin acts like a natural barrier, these patches are limited to the delivery of drugs of small molecular sizes such as nicotine and progesterone. However, the past two years have witnessed spectacular breakthroughs in the field of painless drug delivery. The revolutionary work done in this field promises a novel, safer and more efficient means of administering drugs.

The initial challenge to the development of such transdermal patches for the administration of a wide spectrum of drugs was the size of the molecules.Â Since most drugs are macromolecules in nature, the skin prevents their entry through its surface. However, this problem has been overcome by the development of Microneedles. Created in the late 2000s, micro-needles are extremely minute, only a few microns in dimension, they pierce through the skin in such a way that they traverse the outer barrier layer, the Strateum Corneum, but they do not pierce the nerve endings or cause any bleeding. Hence it is a bloodless and painless means of treatment. They can be fabricated out of metal, silicon dioxide, glass, fibre glass and so many other materials. They can also be solid or hollow. Solid microneedles are often coated with the drug that needs to be delivered to the body like Vitamin B and the hollow ones are used to deliver drugsÂ using a simple pump system. Hollow microneedles can also be used to remove fluids from the body, e.g.,. Glucose for analysis.

The greatest advantage of these needles is the fact that they are painless. In fact, in a particular clinical trial conducted on 12 subjects, using these microneedles, all reported that the sensation of the microneedles piercing the skin was comparable to pressing the skin against a hard surface. The actual piercing could not be felt unlike when a hypodermic needle is inserted in the skin. This is a very important advancement in the field of medicine, especially in pediatrics where children are usually afraid of needles and refuse to take their medicines. Another important advantage is that it allows accurate doses of medicine to be delivered. This is of utmost importance in the case of diabetic patients, who take regular shots of insulin everyday and any mistake in the measurement could cause an insulin overdose. Recently, HP along with Crospon, a medical device manufacturer, has developed a transdermal skin patch. It incorporates the patented HP inkjet technology. Its specialty is that it includes around 150 microneedles and a microchip which automatically regulates the dosage and timing of the drug delivery. It also has around 400 cylindrical reservoirs, so that more than one drug can be delivered at a time, thus being advantageous to patients on multi-drug regime, which is difficult to remember and follow.

Another advantage of the micro-needle drug delivery system is the ease of use and safety. Often young diabetics, especially children, go through the trauma of having to inject themselves twice a day. The micro-needle transdermal drug delivery patch eliminates this hurdle and alsoÂ prevents accidents such as, breaking needles, air pockets in the syringes, etc. It is also extremely safe because the abrasions made by these needles are much smaller than traditional hypodermic syringes and other skin abrasions such as, scratches or cuts. Since it doesnt bleed it reduces the risk of infection.

The ultimate breakthrough, though, in this field has come very recently. Mark Prausnitz, a chemical and biological engineer at Georgia Institute of Technology, has published a paper in the journal Nature Medicine, which talks about transdermal drug delivery patches with dissolvable microneedles for the delivery of vaccines. This idea has taken the world of biomedical engineering by storm as it talks of a safer and possibly more efficient means of vaccination. These needles are made of biocompatible and biodegradable polymers, which when inserted into the skin deliver the medicine and dissolve it into the body. A laboratory test using these needles was done, to deliver the flu vaccine to a group of mice as opposed to the traditional needles that were used for the other group. At the end of a 30 day test period, both the groups of mice showed the same level of resistance gained. To top it all, the mice that were injected using the microneedles showed a lower level of virus in their lungs than the other, proving that this method was probably more effective. Therefore this device sees an optimistic future in vaccination drives around the world, for various viruses, as they are more effective and much more hygienic and safe, as compared to traditional needles, were there have been cases of use and reuse in certain countries with lax medical standards.

Thus, the transdermal micro-needle drug delivery patches are an innovative invention in today’s world. Its advantages of being painless, safe, and hygienic and user friendly are very promising for its commercial growth. But some scientists and organizations are also voicing certain possible disadvantages. Firstly, these microneedles might cause skin irritation and allergy. Secondly, the dissolvable needles raise concerns because the polymers used to manufacture them may become slightly toxic when in the blood stream. And finally, the cost of these patches are little too high for everyone to afford. But these issues are easy to tackle. Allergies can be prevented by using a suitable skin cream or anti-allergenic. The dissolvable needles can be developed using cellulose-based polymers, which are safe to human body. The costs too can be reduced, when they are mass produced. A large number of companies are already in the planning stage to invest in this technology. This would make the product easily accessible and affordable.

Transdermal micro-needle drug delivery patches promise to revolutionize the field of medicine, vaccination and disease treatment. It can effectively attempt to phase out oral medication and thus reduce the time required forÂ treatment. This device is also another triumph of engineering solutions in the medical world, proving how simple technology can be used to solve intractable problems and doing so, it contributes in uniting scientists from various disciplines as well. Thus, the micro-needle transdermal drug delivery patch has the potential to be among one of the most important scientific inventions of modern times.

Rashmi Rajshekhar