If you’re aiming a pill for this part of the stomach, posture is critical to play into both gravity and the natural asymmetry of the stomach.
In what position do you take a pain reliever or a pill for another acute condition or a chronic disease? Are you upright or do you do it lying down on one side or the other?
It makes a difference according to an engineer at Johns Hopkins University engineer and an expert in fluid dynamics, who with his team at the institution of higher learning in Baltimore, Maryland built a model called StomachSim to realistically simulate the mechanics of drug dissolution on the human stomach.
“We were very surprised that posture had such an immense effect on the dissolution rate of a pill”
Rajat Mittal
They found that your posture can make a big difference – as much as an hour longer – in how fast your body absorbs the medicine. “We were very surprised that posture had such an immense effect on the dissolution rate of a pill,” said senior author Rajat Mittal, the engineer. “I never thought about whether I was doing it right or wrong, but now I’ll definitely think about it every time I take a pill.”
The research has just been published in the journal Physics of Fluids under the title “Computational modeling of drug dissolution in the human stomach: Effects of posture and gastroparesis on drug bioavailability,”
“I never thought about whether I was doing it right or wrong, but now I’ll definitely think about it every time I take a pill”
Rajat Mittal
The oral administration route of pills is a safe, economic, and easy way to administer drugs to patients and one that is known to result in a high degree of patient compliance. In recent years, models have been created to authentically represent the workings of several major organs, especially the heart.
How to take a pill
The model developed by the Johns Hopkins team blends physics with biomechanics and fluid mechanics. StomachSim mimics what happening inside a stomach as it digests food, or in this case, medicine.
Most pills do not start working until the stomach ejects their contents into the intestine, so the closer a pill lands to the lowest part of the stomach – the antrum – the faster it starts to dissolve and empty its contents through the pylorus into the duodenum, the top of the small intestine. If you’re aiming a pill for this part of the stomach, posture is critical to play into both gravity and the natural asymmetry of the stomach.
The team tested four postures. Taking pills while lying on the right side was by far the best, sending pills into the deepest part of the stomach to achieve a dissolution rate 2.3 times faster than even an upright posture. Lying on the left side was the worst.
The team was very surprised to find that if a pill takes 10 minutes to dissolve on the right side, it could take 23 minutes to dissolve in an upright posture and over 100 minutes when laying on the left side. Standing upright was a decent second choice, essentially tied in effectiveness with lying straight back.
“For elderly, sedentary or bedridden people, whether they’re turning to left or to the right can have a huge impact”
Rajat Mittal
“For elderly, sedentary or bedridden people, whether they’re turning to left or to the right can have a huge impact,” Mittal said. “Posture itself has such a huge impact it, it’s equivalent to somebody’s stomach having a very significant disfunction as far as pill dissolution is concerned,” he added.
The team also considered how stomachs that aren’t functioning at full strength due to gastroparesis – a chronic condition in which the stomach cannot empty in the normal way and food passes through it slower than usual – caused by diseases such as diabetes and Parkinson’s disease affect the dissolving of pills.
Even a small change in the conditions of the stomach can lead to significant differences in the outcome of an oral drug, said lead author Jae Ho Lee, a former postdoctoral researcher at Johns Hopkins.
Future work will try to predict how the changes in the biomechanics of the stomach affect how the body absorbs drugs and food is processed in the stomach and the effect of posture and gastroparesis on food digestion.