To test pill coatings, try a stomach in a flask | Science News for Students

To test pill coatings, try a stomach in a flask

A teen investigates which type of pill dissolves fastest in the gut
Jun 7, 2017 — 6:50 am EST

Tablets (in white) may dissolve in the stomach fastest, while compressed caplets (in orange, blue and pink) may last longer, a teen found.


LOS ANGELES, Calif. — Pills come in all sorts of shapes and sizes. Some are coated, and some are not. Roshni Sen, 17, wondered if a pill’s coating can affect how long it takes for the pill to break down in the body. To investigate, this senior at the Academy of Science and Technology at The Woodlands College Park in Texas created a “stomach” in a flask. She showed that different types of pills dissolve in different spots in the digestive tract. And that might affect which bottle you would want to reach for when you’ve got aches and pains.

Roshni presented her results at the Intel International Science and Engineering Fair (ISEF). Created by Society for Science & the Public and sponsored by Intel, the yearly fair brings high school students from all over the world together to share their research projects. (SSP also publishes Science News for Students and this blog.)

The teen became curious about how quickly pills dissolve after reading about a new type of pill that was supposed to release medicine inside the body at a constant rate. “I found this paper online talking about this new kind of pill that biomedical engineers made that has a porous outer coating,” Roshni says. It could make a pill’s effects last longer and be more consistent. Realizing how important a coating could be, she soon decided to do an experiment to find out how quickly the different types of pills now for sale dissolved in the stomach and small intestine.

Those pills now on the market come in many shapes and sizes, and with different coatings. Some are liquid inside a gel, or powder inside a gel caplet. Others are tablets or compressed caplets with shiny coatings. This can affect how quickly the medicine inside makes its way into someone's bloodstream.

The teen worked with a drug that's used to treat fever and pain. It's available at any pharmacy and best known by the brand name Tylenol. (Its generic name is acetaminophen and paracetamol, depending on what country you are in.)  Most importantly, Roshni explains, “it comes with all the different kinds of coatings I needed.”

She wanted to examine four common pill coatings. A tablet is the most basic. “It essentially has no coating other than the one that just holds it together,” Roshni says. Compressed caplets have a hard, shiny coating. Gel caplets have a gel coating around a powder, and soft gels are made with a gel coating around a liquid.

Roshni Sen
Roshni Sen presents her project at Intel ISEF.
B. Brookshire/SSP

To test how fast the pills dissolved, Roshni had to come up with a stand-in for the human digestive system. So she created models — simulations — of the stomach and small intestine with acidic solutions in flasks.

The stomach breaks food down so its nutrients can be absorbed by the body. Because of this, the stomach is full of enzymes and acid. The stomach has a pH of around 2. That’s about as acidic as lemon juice or vinegar. The small intestine, where most of the nutrients in food get absorbed, uses mostly enzymes, not acid, to finish digesting the food from the stomach. It is a strong base, with a pH of about 8. That’s about as basic as baking soda. To mimic these environments, Roshni prepared three beakers. One beaker matched the pH of the stomach. Another matched the pH of the small intestine. The third, her ­control, was pure water, which has a pH of 7.

To mimic the body’s temperature, she heated the beakers to 37° Celsius (98.6° Fahrenheit). She added a small stir-bar in each to keep the mixtures moving. This would stand in for the movement in the stomach and small intestine that mixes food and keeps it moving along.

Working in her school’s chemistry lab, Roshni placed a pill in each beaker. She then waited to see how long it took for the pill to completely dissolve. She repeated the experiment five times for each pill type in each beaker.

In water, all of the pills took more than an hour to dissolve. But there were differences in the acidic “stomach.” The tablets, which didn’t have much of a coating, dissolved the fastest, in about 12 to 13 minutes. The soft gels lasted a little longer, taking 15 to 16 minutes to dissolve, while the gel caplets took 18 to 20 minutes. Compressed caplets proved most hardy. They took 24 to 25 minutes to dissolve.

But Roshni got a surprise when she tried to dissolve her pills in her “intestine” flask. The tablets, soft gels and gel caplets took much longer to dissolve in the basic solution, between 28 and 36 minutes. But the compressed caplets, which withstood the strong acid of the stomach, dissolved quickly in the “small intestine,” in 13 to 15 minutes.

Compressed caplets are covered in an extra coating. It protects the pill from the stomach acid. “The main purpose is to elongate the process,” Roshni explains, making sure the pill does not dissolves until it reaches the small intestine. Why? If a pill dissolves in the stomach, the acid there might also break down some of the drug before it can be absorbed. That would make the pill less effective. Waiting to dissolve in the small intestine may ensure that more of the drug makes it into the bloodstream.

Tablets and soft gels could begin to treat pain and fever faster because they dissolve more quickly, Roshni concludes. But they also might be less effective, because some of their medicine will be lost in the stomach. So in some cases, the compressed caplets may prove more effective, she says.

Drug companies design medicines with different coatings for different purposes. Tablets and soft gels may be useful for quick relief. Compressed caplets, in contrast, may bring longer relief.

In the end, what kind of pill you take probably depends on what your needs are. “A lot of people just take a pill and hope it works and kind of forget about it,” the teen says. She hopes that her experiment will help spread knowledge about why different pill coatings exist and what they can do.

And when she’s in need, Roshni prefers speed. “I told my mom I won’t take gel caps or compressed caplets anymore,” she says. “I’m going to take soft gels.”

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Power Words

(more about Power Words)

acidic     An adjective for materials that contain acid. These materials often are capable of eating away at some minerals such as carbonate, or preventing their formation in the first place.

base      (in chemistry) A chemical that produces hydroxide ions (OH - ) in a solution. Basic solutions are also referred to as alkaline. (adj. basic)

biomedical     Having to do with medicine and how it interacts with cells or tissues.

biomedical engineer     An expert who uses science and math to find solutions to problems in biology and medicine; for example, they might create medical devices such as artificial knees.

chemistry     The field of science that deals with the composition, structure and properties of substances and how they interact. Scientists use this knowledge to study unfamiliar substances, to reproduce large quantities of useful substances or to design and create new and useful substances. (about compounds) Chemistry also is used as a term to refer to the recipe of a compound, the way it’s produced or some of its properties. People who work in this field are known as chemists.

concentration     (in chemistry) A measurement of how much of one substance has been dissolved into another.

control     A part of an experiment where there is no change from normal conditions. The control is essential to scientific experiments. It shows that any new effect is likely due only to the part of the test that a researcher has altered. 

dissolve     To turn a solid into a liquid and disperse it into that starting liquid. (For instance, sugar or salt crystals, which are solids, will dissolve into water. Now the crystals are gone and the solution is a fully dispersed mix of the liquid form of the sugar or salt in water.)

engineering     The field of research that uses math and science to solve practical problems.

environment     The sum of all of the things that exist around some organism or the process and the condition those things create. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature and humidity (or even the placement of components in some electronics system or product).

flask     A type of container with a narrow neck. In the laboratory, sterile flasks made from glass are used for conducting chemical and biological experiments.

gel     A gooey or viscous material that can flow like a thick liquid.

Intel International Science and Engineering Fair     (Intel ISEF) Initially launched in 1950, this competition is one of three created (and still run) by the Society for Science & the Public. Each year now, approximately 1,800 high school students from more than 75 countries, regions, and territories are awarded the opportunity to showcase their independent research at Intel ISEF and compete for an average of $4 million in prizes. 

model     A simulation of a real-world event (usually using a computer) that has been developed to predict one or more likely outcomes.

nutrient     A vitamin, mineral, fat, carbohydrate or protein that a plant, animal or other organism requires as part of its food in order to survive.

pH     A measure of a solution’s acidity or alkalinity. A pH of 7 is perfectly neutral. Acids have a pH lower than 7; the farther from 7, the stronger the acid. Alkaline solutions, called bases, have a pH higher than 7; again, the farther above 7, the stronger the base.

porous     The description of a substance that contains tiny holes, called pores , through which a liquid or gas can pass. (in biology) The minute openings in the skin or in the outer layer of plants.

simulation     (v. simulate) An analysis, often made using a computer, of some conditions, functions or appearance of a physical system. A computer program would do this by using mathematical operations that can describe the system and how it might change over time or in response to different anticipated situations.

solution     A liquid in which one chemical has been dissolved into another.

SSP     Short for Society for Science & the Public. This nonprofit organization was created in 1921 and is based in Washington, D.C. Since its founding, SSP has been not only promoting public engagement in scientific research but also the public understanding of science. It created and continues to run three renowned science competitions: The Regeneron Science Talent Search (begun in 1942), the Intel International Science and Engineering Fair (initially launched in 1950) and Broadcom MASTERS (created in 2010). SSP also publishes award-winning journalism: in Science News (launched in 1922) and Science News for Students (created in 2003). Those magazines also host a series of blogs (including Eureka! Lab).

tract     A particular, well-defined area. It can be a patch of land, such as the area on which a house is located. Or it can be a bit of real estate in the body. For instance, important parts of an animal’s body will include its respiratory tract (lungs and airways), reproductive tract (gonads and hormone systems important to reproduction) and gastro-intestinal tract (the stomach and intestines — or organs responsible for moving food, digesting it, absorbing it and eliminating wastes).


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