For patients and doctors, oral medication is often the most desirable way to administer drugs. Among other benefits, swallowing a pill is safer, more convenient and less invasive compared to injections or other means of taking a drug.
But one of the challenges facing oral pills is to be digested by the stomach before they can deliver their payloads and perform their intended effects. Because drugs that are broken down in the stomach are less effective, many treatments currently cannot be taken orally.
As researchers in polymer science and bio-engineering, we wanted to find a way to deliver medicine so that it could resist stomach acid but still dissolve in the right place. In our recently published newspaper, we believe we have developed a new material that can help drugs do just that.
Oral drug challenges
Oral drugs are mainly absorbed in the small intestine, where they then enter the bloodstream and move to the rest of the body. However, to get a drug to the small intestine, it must first get past the highly acidic environment of the stomach, which can worsen medication before it can be absorbed.
To compensate for stomach upset, oral medications usually come in doses that are higher than necessary. This strategy works for very common low molecular weight drugs that have a low mass. They are often more stable and can penetrate cells more easily compared to other types of drugs. However, increasing the dose is not a viable approach for treatments that easily build up to toxic levels, are too sensitive to stomach acidity or are very expensive.
A stomach acid resistant material
To help drugs resist the harsh environment of the stomach, our research team has developed a new type of material called polyswitterionic complexes, or pZCs. pZCs consist of two types of polymers, or large molecules made of a string of repeating smaller molecules. As the name suggests, pZCs are made of polyswitter ions, which are both positively and negatively charged, and polyelectrolytes, which are exclusively positive or negative.
Through a process called complex coavcervation that binds oppositely charged molecules, these two polymers themselves are assembled to form pZC droplets that are sensitive to acidity. In principle, these drops can encapsulate and protect a therapeutic load as it moves through the highly acidic stomach, but disassembles and releases the drug when it reaches the more neutral environment of the small intestine.
We first tested whether the pZC droplets could encapsulate a protein as a test load. Once we were able to successfully place the load in the drop, we then measured how much protein load was released in different acid levels by spectrophotometry, a method that uses light absorption to measure the amount of dust present in a sample. We found that the pZC droplets retained their protein load in acidic conditions and gradually released it as the acidity decreased.
Make drugs more convenient
We believe that our pZC system can enable researchers to develop new and improved ways of delivering drugs through the digestive tract. Our future work will focus on better understanding how pZCs behave when their chemical properties change under different conditions. We are also experimenting with different types of polymers and drug loads.
Our hope is that our methods and conceptual framework will one day increase the number and variety of drugs that can be taken orally, which will make it more convenient to take your medication and improve the lives of patients.