But the pouch, named after Duke’s Pratt School of Engineering, is far more complicated than it appears on the surface. And so too is the decade-long effort that has taken the pouch and the team, including an impressive number of engineering and global health students, from idea to implementation.
That journey began in 2008, when Malkin first heard about the problem of antiretrovirals degrading in storage while chatting with a colleague at a conference. He came back to his lab determined to figure out why this deterioration was happening. He tasked Spohn with testing the two prevailing theories, which had to do with moisture loss from the medication and leaching of the parabens in the medication into the plastic containers.
Spohn tested a variety packaging vessels, including placing a filled syringe in a sealed pouch, based on previous work done by the health organization PATH. His experiments confirmed the moisture loss theory, but by a surprising mechanism. The plastic container—cup, spoon or syringe—was actually absorbing the water, causing the medication to solidify.
The high volume-to-volume ratio of the medication to the plastic of the cup, spoon or syringe was causing the medication to solidify.
“He tried many combinations, and some of them took weeks to investigate,” Malkin remembers. “Through all the experiments, one thing was clear: No matter what you did, if you included the syringe, the results were terrible.”
After the eureka moment with the graph, Spohn and Malkin started working on a pouch that would hold a single dose of the medication. It took another five years to perfect the design, whose humble appearance conceals some complex engineering.
“It’s actually a sophisticated sequence of five thin layers,” Malkin says. “You need to control the exposure to light and air, the surface-to-volume ratio and the volume-to-volume ratio and determine the optimal thickness of each layer.” The first three layers, which took about three years to formulate, are the critical components that preserve the medication.
When the team began testing the pouch with mothers in the field, the initial reactions surprised them.
When the team began testing the pouch with mothers in the field, the initial reactions surprised them. While foilized pouches are commonplace in Western countries, they were unfamiliar to the women in the study, and many had difficulty opening the packets without a knife or scissors.
“Our students analyzed about 5,000 opened pouches under a microscope to determine how the mother interacted with them—for example, how much tear force did she use, how long was the tear and how many failures to tear occurred,” Malkin explains. This detailed analysis, along with further testing in the field, led the team to the current Pratt Pouch design.
Students, mostly undergraduates, have done almost 100 percent of the work. —Bob Malkin
Malkin is quick to point out that “students, mostly undergraduates, have done almost 100 percent of the work,” which has not only kept the project moving forward but has served as real-life inspiration for aspiring biomedical engineers and physicians.
Alexa Choy BS’14, one of the students who investigated tearing practices in Ecuador, notes that “observing mothers using the pouch has left a lasting impact on me and was a critical part of my journey into pursuing a career in medicine.”
After several years of field testing, however, the Pratt Pouch has won women over. Its potential to significantly increase access to antiretroviral medication for babies is critical. Without intervention, the risk of mother-to-child transmission of HIV can be as high as 45 percent, but antiretroviral therapy at delivery potentially reduces the risk to less than five percent. And prevention gives the child the best chance at survival, as more than half of HIV-infected children die before age two.
In addition, women have deemed the Pratt Pouch easier to use and far more helpful in ensuring proper medication dosage for their babies than the conventional spoon, cup and syringe delivery methods.