Recent advances in nanocrystals for arthritis drug delivery

More than 500 million people worldwide suffer from arthritis, experiencing daily pain and inflammation. Current treatments for osteoarthritis (OA) and rheumatoid arthritis (RA) are palliative, offering only symptom relief. No disease-modifying OA drugs (DMOADs) capable of restoring joint functionality and regenerating the cartilage matrix have yet been approved by the FDA or EMA. This review highlights recent advances in nanocrystals for arthritis drug delivery, including conventional nanosuspensions and novel transdermal microneedles. Special attention is given to intra-articular DMOADs formulated as nanocrystal-in-microparticles, designed to extend drug release over months. Papers and reviews with the mentioned contents and published over the last 5 years were included in the review process. New DMOADs and disease-modifying antirheumatic drugs (DMARDs) are often poorly water-soluble, limiting their clinical progress. The versatility of nanocrystals and nanosuspensions offers a potential advantage over other types of nanoparticles, as they can be adapted to various delivery systems, administration routes, and types of arthritis. Due to the avascular nature of cartilage, exploring the intra-articular route for OA management is essential. Implementing cartilage-targeted strategies or using stimuli-responsive hydrogels can further enhance their therapeutic potential.