Researchers have developed a capsule that can deliver a week's worth of HIV drugs in a single dose, an advance that could make it much easier for patients to adhere to their dosing schedule.

Patients can take it just once a week and the drug will release gradually throughout the week.This type of delivery system could not only improve patients' adherence to their treatment schedule but also be used by people at risk of HIV exposure to help prevent them from becoming infected, the researchers said."One of the main barriers to treating and preventing HIV is adherence," said Giovanni Traverso, a research affiliate at the Massachusetts Institute of Technology.

"The ability to make doses less frequent stands to improve adherence and make a significant impact at the patient level."The new drug, detailed in the journal Nature Communications, has a star structure, with six arms be filled with a different drug-loaded polymer. This makes it easier to design a capsule that releases drugs at different rates."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," Traverso said.

The tests conducted on pigs showed that the capsules were able to successfully lodge in the stomach and release three different HIV drugs over one week.The capsules are designed so that after all of the drug is released, the capsules disintegrate into smaller components that can pass through the digestive tract.Importantly, the researchers found that going from a daily dose to a weekly dose could improve the efficacy of HIV preventative treatment by approximately 20 per cent.When this figure was incorporated into a computer model of HIV transmission in South Africa, the model showed that 200,000 to 800,000 new infections could be prevented over the next 20 years, the researchers said.