Chronic retinal diseases, such as diabetic macular edema and exudative age-related macular degeneration, are currently treated with intravitreal drug injections. Although the treatment is not very painful and the drugs used have no particular side effects, there are some indications/practices that the patient must follow during and after the injections:
- The injection is performed, under topical anesthesia, in a controlled environment, in sterile conditions in order to avoid infections;
- Post-injection therapy based on eye drops must be followed;
- The first check is performed in the clinic the following day.
If we consider that the treatments take place once per month, sticking to these indications is challenging for patients, caregivers and for the national healthcare system. For these reasons, is difficult to strictly follow the protocol of injections and some patients do not strictly follow the treatment regimen, ending in an under-dosing of the therapy.
To overcome these limitations, a group of researchers from the Department of Chemistry, Materials and Chemical Engineering “Giulio Natta” of the Politecnico di Milano in collaboration with the Department of Clinical and Biomedical Science “Luigi Sacco”, ASST Fatebenefratelli-Sacco, University of Milan, developed Mag Shell: a device that, with a single injection, is able to release multiple doses of drug at pre-set time intervals.
The device is composed of layers of biodegradable materials (shells) alternated to layers of drug. The shells are made of magnesium or its alloys. Magnesium is a material characterized by a low corrosion resistance in biological fluids and biocompatible degradation products. The corrosion of the first layer of magnesium causes the release of the first dose of drug; once the drug is well distributed in the eye, a new layer of magnesium is eroded, with timing related to the requested therapy. In this way, the drug is released in doses at pre-set time intervals, replicating the optimal therapies, and not continuously like with the traditional drug-release methods.