Doctors sometimes prescribe the steroid prednisone to help tame inflammation in people with rheumatoid arthritis (RA), especially early in the illness. Although this medication reduces disease activity, dosing must be carefully controlled so that its side effects, such as loss of bone density, don’t outweigh its benefit. Now researchers have developed a way to give the drug that maximizes its therapeutic effect, perhaps allowing doctors to reduce the dosage.

Scientists know that RA alters a person’s circadian rhythm—the body’s response to the daily cycle of light and dark—causing the release of an inflammation-promoting chemical late at night. As a result, RA symptoms tend to be worse in the early morning. With this in mind, a group of German researchers developed a form of prednisone that becomes active about four hours after it’s swallowed.

In a recent trial, 288 people with active RA received either the modified-release prednisone, at bedtime, or regular prednisone, at the usual time, in the morning. When comparing the groups, investigators found that the duration of morning joint stiffness was reduced by 22% more in those who had gotten the modified-release prednisone than in patients who received the immediate-release version.

The researchers say that although the prospects for use of the more effective modified-release prednisone look good, more research is need to be sure of its long-term safety and efficacy.