Medically Reviewed By Vikas Londhe M.Pharm (Pharmacology)
MIT scientists have developed a self-injectable, long-acting drug delivery system using microcrystals. Learn how this innovation could transform contraception and chronic disease treatment.
Imagine a single injection that lasts for months, delivered through a tiny needle you can use yourself, no surgery, no hospital visit. Thanks to a groundbreaking innovation from researchers at Massachusetts Institute of Technology (MIT), that future is now one step closer.
MIT researchers have introduced a groundbreaking innovation that could make this vision a reality. Called SLIM; Self-aggregating Long-acting Injectable Microcrystals this new drug delivery system offers extended release, smaller needle size, and high drug potency, all packed into a single self-administered injection.
A New Way to Take Medicine: Once Every Few Months
Researchers at MIT and Harvard-affiliated Brigham and Women’s Hospital have developed a new drug delivery system called SLIM, short for Self-aggregating Long-acting Injectable Microcrystals.
Instead of needing large needles or surgery, SLIM allows medicine to be injected just under the skin through a tiny needle. Once injected, the medicine automatically forms a small solid “implant” that slowly releases the drug over several months.
This method is especially promising for medications like birth control and HIV medicine where convenience, privacy, and reliability are essential
Global Health Impact
For millions worldwide especially women in under-served regions SLIM could mean:
No need for surgical implants or repeated clinic visits
Empowered self-administration of essential medications
Lower costs and better access to long-term contraception
This new technology is published in the journal Nature Chemical Engineering. The technology also aligns with public health goals from organizations like the WHO and the study is co-funded by Gates Foundation.
How It Works: Tiny Crystals, Big Impact
SLIM works by suspending drug particles called microcrystals in a liquid. When injected into the body, this liquid mixes with the body’s water and causes the particles to clump together into a compact, slow-dissolving depot.
Less pain, smaller needles: Unlike other long-acting injections that require thick, painful needles, SLIM uses fine needles as small as 30 gauge (about the width of a human hair).
Fewer additives: Most long-acting shots rely on lots of added slowly degrading polymers such as polylactic acid or polycaprolactone to slow down drug release. SLIM only needs a tiny amount, reducing risks of side effects and injection pain.
Why It Matters: Especially for Women and Low-Resource Settings
In many parts of the world, women may not have easy access to clinics for repeated contraception or medications. Self-injectable treatments could empower them to take control of their health privately and conveniently.
This is a big step beyond current injectables like Depo-Provera, which lasts 3 months but can’t match the long-lasting protection of surgical implants like Nexplanon. SLIM offers the best of both: long-lasting protection with no surgery required.
A Breakthrough for Contraceptive Delivery
The researchers tested SLIM using levonorgestrel, a common hormonal contraceptive. In lab studies on rats, the SLIM formulation:
In early tests, the SLIM injection worked really well. After being injected, it formed a small, solid implant under the skin that stayed in place. It released the medicine much more slowly up to 5.6 times slower than current options, helping it last longer. The implant stayed strong and stable for over 3 months, and the injection was easy enough to be done at home using a regular small syringe. This means that women could get fewer injections while still having reliable, long-term birth control.
Bottom Line: Why This Matters for the Future of Medicine
The researchers plan to test SLIM with other drugs, especially those that are hard to dissolve in water, like many modern medications.
They’re also studying how to fine-tune drug release and improve safety for human use.
Because of its compact, stable design, SLIM could become a game-changer for treating chronic conditions like mental health, HIV prevention, or cancer with fewer doses and better adherence.
The SLIM system could redefine how we take medicine offering safer, longer-lasting, and more comfortable treatment through self-administered injections. It’s a promising leap toward better access and better outcomes, especially in global health.
Long-acting injectables are a proven way to boost adherence, especially for chronic conditions. But current systems are limited by: Large, painful needles, Viscous, hard-to-inject formulations and Poor suitability for self-administration.
SLIM overcomes these barriers with smart design: high drug loading, low viscosity, and small injection size all while delivering long-lasting effects.
Reference
Feig, V. R., Park, S., Rivano, P. G., et al. (2025). Self-aggregating long-acting injectable microcrystals. Nature Chemical Engineering, 2(3), 209–219. DOI: 10.1038/s44286-025-00194-x
Engineers develop a better way to deliver long-lasting drugs, MIT News, Massachusetts Institute of Technology, 24 March 2025
Owen A, Rannard S. Strengths, weaknesses, opportunities and challenges for long acting injectable therapies: Insights for applications in HIV therapy. Adv Drug Deliv Rev. 2016 Aug 1;103:144-156. Doi: 10.1016/j.addr.2016.02.003. Epub 2016 Feb 23. PMID: 26916628; PMCID: PMC4935562.
McEvoy, Joseph. (2006). Risks versus benefits of different types of long-acting injectable antipsychotics. The Journal of clinical psychiatry. 67 Suppl 5. 15-8.
National Research Council (US) Committee on Population. Contraception and Reproduction: Health Consequences for Women and Children in the Developing World. Washington (DC): National Academies Press (US); 1989. 4, Contraceptive Benefits and Risks.Available from: https://www.ncbi.nlm.nih.gov/books/NBK235069
Source of the Video: Giovanni Traverso (YouTube) _Self-Aggregating Long-Acting Injectable Microcystals
Disclaimer: The video is for educational and informational purposes only.
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