Simply researching and developing a promising drug is often not enough. Engineers need to figure out how to get the medicine to where it is needed, when it is needed and at the proper dosage needed. A simple pill might not always be the best solution.
“If something needs to get directly to your bloodstream, a lot of times, an injection is the only way to do it, because going through the GI tract may lessen the impact of the product,” says Jennifer Zieverink, senior director, marketing and alliance management at Aprecia Pharmaceuticals. And that is just one of many functional considerations.
Robert Langer, an institute professor at the Massachusetts Institute of Technology and a major figure in biotechnology, lists the factors engineers have to weigh before arriving at a design solution for drug delivery: Is the patient going to swallow it, is it going to be an aerosol, or are you going to develop an implant or a transdermal patch?
“You have to make sure it is safe, get the right release kinetics and then figure out how to manufacture it on a large scale so millions of people can access the drug,” Langer says.
Engineers also have to focus on patient adherence. After all, a drug can only be effective if the patient actually takes it as needed. Fortunately, recent engineering advances, particularly in the fields of 3D printing and implantables, have significantly affected all factors related to drug delivery.
For example, Aprecia’s SPRITAM checks all the boxes Langer lists and uses 3D printing technology to do so. Designed to treat epilepsy, SPRITAM delivers a high dose load that rapidly disintegrates with a single sip of water. Disorders affecting the central nervous system are prime candidates for such improvements because the disorder often affects the patient’s ability to swallow pills, according to Zieverink. The problem is exacerbated when patients need a high dosage strength, which means large (or large amounts of) pills.
Aprecia delivers a porous tablet that is not compressed but held together with minimal amounts of liquid. Using 3D printing, the binding agent is delivered in precise locations within the powder. Aprecia had to calibrate the print head and the fluid mechanics of product delivery so SPRITAM could be manufactured on a large scale to meet demand.
While SPRITAM resolved problems related to large load drug delivery, the drug Yutiq addresses another headache for engineers: how to get the medicine to where it is needed. In this case, the drug (fluocinolone acetonide) is released through a tiny implant injected into the eye to treat posterior uveitis, a potentially blinding eye disease. Eye drops are ineffective and can cause glaucoma, so the implant delivers a tiny amount of the drug—the equivalent of one eye drop—over three years. At the end of three years, if the disease returns, patients receive another implant. These devices are stable in the eye.
The implant has to fit into a fine needle, and the release rate has to stay constant over years, according to Paul Ashton, inventor of Yutiq and president and CEO of Inflammasome Therapeutics.
“We ended up with cylinders of an impermeable polymer ‘straw’ capped with a permeable polymer to allow drug diffusion,” he says. “Other complications were finding polymers that are biocompatible and could be manufactured with a very high level of precision. We also had to engineer the injector system to administer the delivery device. To maximize the volume available, it was necessary to use extra-thin wall needles, but it is very hard to make these sharp enough to penetrate the white of the eye, the injection site.”
Each of these solutions is tailored to address specific drug delivery challenges. Overall, as Zieverink puts it, “drug delivery is really about finding better ways to get the medicine into the body effectively.” Implantables and 3D printing continue to make that task more precise and effective.