There's a problem with using antiretroviral drugs to treat or prevent HIV – because multiple drugs need to be taken on a daily basis, many patients simply don't bother to keep doing so. What if they just had to take one capsule once a week, though? Scientists at MIT, along with colleagues at Brigham and Women's Hospital, are working on making that a reality.

The MIT/BWH team has adapted an experimental form of drug delivery that was first announced in 2016.

As we explained at the time, the system is based around a small star-shaped assembly that has six rigid polymer arms, each of which is loaded with medication. Those arms are joined together by a biodegradable elastic core, which allows the arms to be folded inward like the ribs of an umbrella. Once the arms are thus folded, the whole thing can be placed inside a standard gelatine capsule and swallowed.

Upon reaching the stomach, the gelatine dissolves, thus releasing the star and letting its arms open back up. In that configuration it's too large to pass out of the stomach, yet it's still unobtrusive enough that it doesn't produce a blockage.

For the next two weeks (or whatever time period it's designed to cover), its arms continuously release their pharmaceutical payload, which is absorbed through the stomach lining. By that point, the star's core has dissolved to the point that the arms break off and proceed into the digestive tract. They're small enough that they will pass harmlessly through it, being excreted with the feces.

Previously, the system had been used to deliver the malaria drug ivermectin, within pigs. This time around, things were a bit trickier – it was being used to simultaneously deliver three antiretrovirals, all at different rates. For that reason, although the "backbone" of all six arms was still made from a single type of structural polymer, the parts of the arms that actually contained the drugs were made of different polymers, that released the drugs over different amounts of time.

In lab tests, once again performed on pigs, the capsules were shown to satisfactorily deliver the correct dosages of the antiretrovirals for a period of one week. The scientists believe that it should be fairly simple to load the capsules with other medications, so that other diseases could be similarly treated.

The technology is being developed by spinoff company Lyndra, which is working toward a clinical trial on humans. A paper on the research was recently published in the journal Nature Communications.

Sources: MIT, Brigham and Women's Hospital