Novel approach for long-lasting contraceptives
A new approach to drug formulation may enable the self-administration of drugs that last up to 2 years.
With some drugs, like contraception, the requirement to take a pill daily can be a barrier for users. Now, researchers from the Massachusetts Institute of Technology (MIT; MA, USA) have devised a formulation that enables long-lasting medications to be self-administered. The approach could prove useful for contraceptives and other drugs that need to be administered over extended periods of time.
There is a high demand for long-acting drug delivery systems that can be self-administered through subcutaneous injection. These technologies are particularly important for people in low-resource settings, where access to medical infrastructure may be limited.
However, combining long-acting injectables with self-administration poses challenges. The precipitating polymers necessary to ensure long-term drug release often require the use of wider needles, which are not suitable for self-administration. To address this, the researchers aimed to create a drug formulation that would last for up to 2 years and could be injected with a small-gauge needle suitable for self-administration.
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In the study, the researchers used a contraceptive called levonorgestrel, which is a hydrophobic molecule that can form crystals. They found that suspending the crystals in a biocompatible organic solvent – called benzyl benzoate – caused the crystals to self-assemble into a highly compact drug ‘depot’, which releases the drug gradually over time. As the formulation didn’t need large amounts of polymer, it could be easily injected through a small-gauge needle.
Changing the density of the depot by adding small amounts of polymer altered the rate at which the drug molecules were released. “This demonstrates the tunability of our system, which can be engineered to accommodate a broader range of contraceptive needs as well as tailored dosing regimens for other therapeutic applications,” commented co-author Sanghyun Park.
The researchers tested their approach by injecting the formulation into rats and found that the depots remained stable and released the drug gradually for 3 months, with around 85% of the drug remaining in the depot after this period. “We anticipate that the depots could last for more than a year, based on our post-analysis of preclinical data. Follow-up studies are underway to further validate their efficacy beyond this initial proof-of-concept,” Park explained.
As the depot is compact enough to be surgically removed if needed, the approach could be used to deliver a range of drugs, including those used to treat neuropsychiatric conditions, HIV and tuberculosis.
The researchers are now looking at translating the formulation to humans, first conducting advanced preclinical studies in a more clinically relevant skin environment.
“This is a very simple system in that it’s basically a solvent, the drug, and then you can add a little bit of bioresorbable polymer. Now we’re considering which indications do we go after: Is it contraception? Is it others? These are some of the things that we’re starting to look into as part of the next steps toward translation to humans,” concluded senior author Giovanni Traverso.
