Working on Pills and Needles
By Heather Offermann
When given the choice between swallowing a pill or receiving a shot for drug delivery, most people would choose the oral method. In fact, approximately 20 percent of the population has a fear of needles.
The problem is, oral drug delivery is a poor method for administering drug absorption into the bloodstream and makes drug delivery a lengthy process. In comparison, injections allow for a quicker process by shooting the drug straight into the bloodstream. To overcome the uneasiness that most people experience while receiving a shot, researchers have developed a strategy to combine pills with faster, more successful drug delivery.
Engineers from the Massachusetts Institute of Technology and researchers from Massachusetts General Hospital are collaborating to develop a hybrid pill that begins with standard oral delivery, but ends with a shot in the stomach. In other words, this newly developed microneedle pill, described in a recent study published in the Journal of Pharmaceutical Sciences, is swallowed and later converted into an injection mechanism during digestion. Once the pill hits the stomach, the outer coating dissolves and stainless steel needles are revealed to inject the surrounding tissue with the drug. One portion of the pill contains a designated reservoir for holding the drug, and the rest of the pill has a pH-responsive coating surrounding the microneedles, which dissolves according to surrounding pH levels.
This method may sound intimidating and painful, but the MIT researchers are focused on studying the effectiveness and safety protocols of microneedle delivery. Yorkshire pigs were the subject of choice for the research project because they have strikingly similar gastrointestinal (GI) tracts to humans. The progress of digestion of a two-centimeter hybrid pill containing insulin in the animal was tracked by serial X-ray, and was found to induce no damage or pain to the surrounding tissues.
The studies were conducted on three pigs of similar weight, each receiving a different systematic delivery of insulin through the microneedle pill. One was delivered through the stomach, another through the colon, and the third through a part of the small intestine. The stomach delivery method is the traditional route for the GI pathway.
The fact that the pill has so far been readily accepted by the GI tract can be supported by the surprisingly easy passing of various foreign objects that we occasionally hear about in the news. For example, in 2006, an inmate from Central Prison in Raleigh, North Carolina successfully swallowed objects such as batteries and bed springs in pursuit of leaving the prison to gain hospital visits. The GI tract accepts a range of objects with varying sizes and textures, which led the researchers to be confident in successful pill digestion.
Biologic drugs such as insulin cannot be delivered orally due to the drug’s susceptibility to bacteria and the fact that insulin, a large macromolecule, cannot withstand the extreme pH conditions of the gastrointestinal tract. Insulin needs to be injected straight into the blood to control sugar levels efficiently, but unfortunately, injections are inconvenient and often dangerous for both doctors and patients. With this new technology, insulin can be secreted more safely and successfully via GI tract injection.
After numerous damage-free experiments on pigs, the researchers found that the blood-glucose levels after insulin injection via microneedles were lower than with the traditional form of injection, and the drug also started to work more quickly when the microneedle was used. This resulted in a faster delivery and faster depletion of glucose levels.
The microneedle pill is not yet perfect, but the research and development are underway for the innovation of drug delivery. Various prototypes are being designed by chemical engineers in order to insure the safest and quickest delivery possible, including the use of materials other than stainless steel to provide biodegradable needles. Do these pills represent the future of effective medicine?
Journal of Pharmaceutical Sciences (2014). DOI: 10.1002/jps.24182.