MIT team develops 'years-long' drug delivery tech
Researchers in the US have devised a new depot system that could provide months or even years of delivery from a single subcutaneous injection.
The team from Massachusetts Institute of Technology (MIT) have suggested that the technology could be useful for applications like long-lasting contraceptives or other medicines that need to be given over extended periods, such as antiretrovirals for HIV or drugs to control chronic psychiatric conditions like schizophrenia.
Their drug delivery approach – which has been published in the journal Nature Chemical Engineering – relies on formulating the drugs as a suspension of minute crystals that self-assemble into a depot after injection. The crystals can be injected using narrower gauge needles than are needed for current depot formulations, making dosing less painful for patients and potentially suitable for self-administration.
The project has arisen out of an effort funded by the Gates Foundation to expand contraceptive options, particularly in lower- and middle-income countries (LMICs), and has resulted in a depot that can last between six months and two years.
"The overarching goal is to give women access to a lot of different formats for contraception that are easy to administer, compatible with being used in the developing world, and have a range of different timeframes of durations of action," commented Vivian Feig, one of the lead authors of the paper, who was formerly at MIT, but who is now an assistant professor of mechanical engineering at Stanford University.
"In our particular project, we were interested in trying to combine the benefits of long-acting implants with the ease of self-administrable injectables," she added.
Current formulation technologies for depots rely either on dispersing the medicine through the tissue after injection, typically lasting up to three months, or using polymers that increase the volume that needs to be injected.
The MIT team tested a formulation of the contraceptive drug levonorgestrel, which forms crystals that are not water-soluble, which was suspended in benzyl benzoate solvent. The solvent takes a long time to get absorbed in the body, allowing the levonorgestrel crystals to clump together as a depot.
In animal models, 85% of the active drug in the injection was still present after three months, although, as yet they have not been able to determine accurately how long therapeutic levels can be maintained.
Adding small amounts of polymer – 1.6% of the injected volume versus up to 98% for current depot formulations – allows the release rate of the active ingredient to be fine-tuned, according to the researchers.
They are now carrying out further studies to see how the technology could work in the delivery of long-acting medicines to human subjects.
Photo by Sweet Life on Unsplash
