HIV therapy involves a combination of drugs that must be taken once or twice daily, making treatment adherence challenging for many people. But researchers may have found a solution to this problem, in the form of a pill that only needs to be taken once per week.
Researchers from the Massachusetts Institute of Technology (MIT) and Brigham and Women's Hospital — both located in Boston, MA — have developed an ingestible capsule that can slowly release 1 week's worth of antiretroviral drugs.
The team's novel creation has the potential to transform HIV therapy, as it means that people may only need to take a single pill once every week, rather than multiple medications every day.
Co-lead study author Robert Langer, the David H. Koch Institute Professor at MIT, and his colleagues believe that their "pillbox in a capsule" could combat the current problem of adherence to antiretroviral therapy;
Langer and his colleagues recently
HIV and antiretroviral therapy
HIV is a virus that attacks and destroys immune cells that are important for staving off infection and disease. If left untreated, HIV can progress to AIDS, wherein a person's immune system is so severely damaged that they become vulnerable to serious illnesses.
In 2016, there were around 36.7 million people across the globe living with HIV or AIDS. Of these individuals, around 1.8 million were newly infected.
Just 30 years ago, HIV was considered by many as a death sentence. Today, the virus can be successfully managed with antiretroviral drugs, which work by reducing the level of HIV in the body.
A combination of different antiretroviral drugs must be taken every day in order for treatment to be successful, but patients can find it hard to stick to such a regimen.
"One of the main barriers to treating and preventing HIV is adherence," notes the study's co-author Giovanni Traverso, of the MIT's Koch Institute for Integrative Cancer Research. "The ability to make doses less frequent stands to improve adherence and make a significant impact at the patient level."
"These slow-release dosage systems perform equal or better than the current daily doses for HIV treatment in preclinical models," he adds.
Building the 'pillbox in a capsule'
With this in mind, the researchers decided to build on an idea that first emerged in 2016, which was an ingestible capsule that could remain in the stomach for 2 weeks and deliver drugs.
For their latest study, the team looked at whether the capsule could be effective for the treatment of HIV, but some design changes were required.
The original capsule consisted of six arms made of a single, strong polymer. Each arm was loaded with drugs and folded in. After ingestion, the arms folded out and released the drugs.
For the treatment of HIV, however, the capsule would need to be able to release different drugs at different rates — something that the original design did not allow.
As such, the team adapted the design. The main structure of the new capsule is still built from a single, strong polymer, but each of the six arms can hold a different medication, thanks to the addition of "release polymers."
"In a way, it's like putting a pillbox in a capsule. Now you have chambers for every day of the week on a single capsule," says Traverso.
Pill effective in pigs
To test whether the newly designed capsule could be effective against HIV, the researchers loaded it with three different antiretroviral drugs — dolutegravir, rilpivirine, and cabotegravir — that are currently used to both prevent and treat HIV.
On testing the drug-loaded capsule on pigs, the researchers found that the capsule successfully settled in the animals' stomachs, and they gradually released each of the three drugs over a 1-week period.
Once all of the drugs are released, the capsule disintegrates, allowing it to be passed through the gastrointestinal tract.
Of course, the capsule needs to be tested in humans before it can be used for the prevention and treatment of HIV, but the researchers believe that their study results show promise.
The researchers calculated the potential impact of this once-a-week capsule at population level, and they suggest that the pill could boost preventive treatment efficacy for HIV by 20 percent. Also, approximately 200,000–800,000 new HIV infections could be prevented in South Africa over the next 20 years.
Commenting on the findings, Anthony Fauci — director of the National Institute of Allergy and Infectious Disease, which helped to fund the study — says, "A longer-acting, less invasive oral formulation could be one important part of our future arsenal to stop the HIV/AIDS pandemic."
"New and improved tools for HIV treatment and prevention, along with wider implementation of novel and existing approaches, are needed to end the HIV pandemic as we know it. Studies such as this help us move closer to achieving this goal."