Just Add Water
After Hurricane Maria devastated Puerto Rico and obliterated its electrical grid, medical workers had to scramble to keep temperature-sensitive medicines, like insulin and vaccines, cold. This scenario is common during disasters. And in developing countries, where refrigeration is scarce, it’s a daily problem. Many vaccines and therapeutic medicines are made out of components derived from living organisms and they need to be kept cold, from the point of manufacture to the time they get to the patient.
“You can imagine that if you want to ship a therapeutic to a developing country or a remote location or, say, after a natural disaster, you may be dealing with high temperatures,” says David Karig, a biological engineer at the Johns Hopkins Applied Physics Laboratory. “So we felt it was important to look into high temperature stability.”
Now, Karig and a team of biological engineers from APL have discovered a way to store and transport these medicines by preserving them in a dried pellet form capable of withstanding heat.
Traditionally, chemists made most medicines by mixing a variety of shelf-stable chemicals and compounds: a dose of acetylsalicylic acid here, a few milligrams of carnauba wax there, and voilà! Aspirin. Refrigeration wasn’t required.
But as new drugs were developed, the rules changed. These are derived from living organisms and need to be cold. Today, there’s a whole class of promising new medications derived from living cells known as biologics. These are prescribed for everything from anemia to cancer, including some ailments traditional drugs can’t treat. As more biologics become available, the need for transportation and storage that’s not dependent on temperature is even more important.
The solution, Karig believed, was to transport the ingredients for making a drug rather than trying to transport the drug itself.
He and his team focused on an existing method of making biologics that allows you to preserve the therapeutic in dried form. The problem was that no one had found a way to make the dried components heat-resistant.
Karig drew inspiration from nature. Some plants and animals are known for surviving extreme drought and dehydration, and they owe that ability to a sugar called trehalose. (One of these is the “resurrection plant,” native to the Southwest, which appears to come back to life after years without water.) Karig added trehalose to his mix and found that even after being exposed to months of sweltering summer temperatures, the dried substance still made effective medications.
When it comes to reconstituting the pellets into a therapeutic, two other ingredients are crucial: water and a dash of dried DNA. This DNA has been coded for whatever biologic you intend to make, and it acts as the drug’s instruction manual; it tells the components in the dried pellet how to re-form into the appropriate therapeutic. This DNA has also been successfully dried and does not require cold storage.
If Karig’s heat-resistant drugs were available, a health care worker might simply head over to her library of drug ingredients, select a DNA vial coded for insulin, mix that DNA with water and the base pellet, and presto, problem solved.
Their discovery could have broad implications. Say a hurricane like the one that hit Puerto Rico last year knocks out the power. As a result, the insulin supply has gone bad. If Karig’s heat-resistant drugs were available, a health care worker might simply head over to her library of drug ingredients, select a DNA vial coded for insulin, mix that DNA with water and the base pellet, and presto, problem solved. “It’s fairly simple,” he says. “You’re literally adding water and mixing the right amounts.”
That’s good news for disaster victims and for people in developing countries who lack vital medications because of transit and storage concerns.
By using a sugar called trehalose, David Karig discovered how to keep dried medications stable in high temperatures.