Injectable Hydrogel Keeps Osteoarthritis Drugs Inside the Joint for Weeks

Researchers at the University at Buffalo have developed an injectable hydrogel — a water-based gel material — that keeps osteoarthritis drugs inside an affected joint for several weeks after a single, minimally invasive injection. Once inside the joint, the material rapidly changes from a liquid into a semi-solid depot at body temperature, releasing medication gradually where it is needed.

Osteoarthritis, the most common form of arthritis, develops as cartilage and other joint tissues gradually break down, causing pain, stiffness, swelling and reduced mobility for millions of people worldwide. Current joint injections — painkillers, corticosteroids and viscosupplements, which are lubricating fluids — generally offer only temporary relief and do not consistently slow the disease. A key obstacle is that drugs disappear quickly from synovial fluid, the fluid that lubricates joints, while poorly water-soluble therapies are hard to deliver at effective doses without exposing the rest of the body.

The new platform combines a polymer matrix with drug-loaded nanocarriers — tiny particles that hold medication — and can carry large amounts of poorly soluble compounds. Drugs are released gradually through diffusion and relaxation of the matrix, maintaining controlled exposure within the joint. The biocompatible system uses materials with previous regulatory acceptance, which the team says should help support clinical translation. It has been validated using a SIRT6 activator, a compound that boosts the activity of the protein SIRT6.

The hydrogel serves a dual function, acting both as a sustained-release drug system and as a viscosupplement that improves joint lubrication. It is designed to carry disease-modifying therapies that target biological processes involved in osteoarthritis, including chronic inflammation and cellular senescence — the build-up of aged cells that stop dividing — and it can be adapted for other hydrophobic compounds, different therapeutic payloads and other joint-related applications.