Fat coated drugs improve arthritis

Enclosing steroids in tiny fat droplets called liposomes may result in a more effective treatment of arthritis, according to a recent animal study. Coating liposomes with a chemical called polyethylene glycol (PEG) increases the survival of these compounds in the blood. This enhanced longevity means that the liposomes have more opportunity to reach the inflamed joints seen with arthritis. Although the liposomes have no anti-inflammatory effects, they can be used to deliver drugs that do, such as steroids. Researchers from the University Hospital Nijmegen in the Netherlands, used a mouse model of arthritis to compare the effects of the steroid prednisone when given alone or inside a PEG liposome. Both formulations were given by injection and were started a few days after arthritis symptoms began. A single treatment with liposomal prednisone produced strong and lasting resolution of joint inflammation. In contrast, free prednisone was just slightly effective and only after repeated treatments. Joint inflammation returned one week after liposomal treatment, but testing of knee specimens showed that cartilage damage was still attenuated. Further testing revealed that liposomes accumulated in inflamed joints, but were not found in unaffected joints. The study indicates that selective targeting by PEG-liposomes of the inflamed joint can strongly enhance the beneficial effects of steroids for arthritis.