When you take a pill, it begins a very long and tortuous journey into your stomach, through your twisted intestines, and then into your bloodstream.
But it can interfere with absorption, so the stomach can take up to an hour longer to dissolve oral medications – depending on your posture.
That’s the conclusion of a new study by researchers at Johns Hopkins University that simulates how pills and tablets dissolve in the human stomach and are released into the upper intestine.
They found that the ideal posture for the fastest absorption is to lean on your right side rather than sitting upright.
“We were very surprised that the pose had such a large effect on the dissolution rate of the pill,” says Rajat Mittal, a computer scientist who studies fluid dynamics at the Johns Hopkins School of Medicine.
“I never thought about whether I was doing it right or wrong, but now I definitely think about it every time I take a pill.”
Less immediate, but more convenient than injectable drugs, oral drugs are absorbed into the bloodstream through the gut. To get there, it must first pass through the stomach and the pylorus, a valve that opens and closes during digestion.
While you may not be too concerned about how quickly your body absorbs vitamin supplements, drug absorption can have serious consequences for how quickly pain relievers work or how long-term the medication can stabilize your blood pressure.
So Mittal and his colleagues tested four poses using a computer model of the human stomach based on high-resolution body scan images of a 34-year-old man.
The model, called StomachSim, simulated the fluidity and biomechanics of the pill as it moves through the digestive tract and how quickly it is expelled from the stomach to the duodenum, the first part of the digestive process.
Taking pills on the right side or lying down meant that the drug was injected deeper into the computer’s stomach and would “dissolve” the pills twice as fast when sitting upright.
Lying on the left side or leaning over slowed down the dissolution process, so it took five times longer for the tablets to be absorbed in this position.
“For people who are older, sedentary, or bedridden, whether they turn left or right can make a big difference,” explains Mittal.
Previous studies have similarly found that lying on the right side increases the rate at which the stomach empties food into the intestine, and that sitting, standing, or lying on the right also increases the absorption of oral medications.
To take it a step further, the researchers simulated what would happen to pill absorption if someone had a condition called gastroparesis, in which nerves are damaged or stomach muscles are weakened, stopping or slowing the stomach from emptying itself properly.
They found that even a small reduction in the simulated digestive power of the stomach led to noticeable differences in the rate of its absorption and the release of the pill into the duodenum – similar to changes in posture.
“The posture itself has such a profound effect on it that it equates to a very serious dysfunction in someone’s stomach in terms of dissolving pills,” says Mittal.
Of course, a lot happens after drugs and food pass through the stomach, into the intestines, and finally into the bloodstream. Remember that computer simulations are useful, but very simplified models of complex processes.
How much liquid, gas, and food you have in your stomach can affect absorption, but the researchers didn’t model that.
“Despite these and other limitations, we have shown that computational models and simulations of gastric fluid mechanics can provide useful and unique insights into the complex physiological processes underlying drug dissolution,” the team writes.
How our body processes drugs can be out of our control because of our genes.
In a field called pharmacogenetics, studies of the genes that code for enzymes that break down compounds explain why people respond to the same drugs in different ways — differences that can be traced back to our prehistoric cousins, the Neanderthals.
So, while your posture can make a big difference in how quickly your body absorbs oral medications, there’s much more to the story.
Your best bet to make sure the medication is effective is to remember to take the pills first and as prescribed.
The study was published Physics of liquids.