Effects of alternate-day prednisone therapy on respiratory function in myasthenia gravis.

To determine the effects of alternate-day prednisone therapy on respiratory function in myasthenia gravis, eight patients were evaluated during "days on" and "days off" prednisone. The patients were treated with long-term (up to three years), high-single-dose, alternate-day oral prednisone. After patients had been controlled with alternate-day prednisone they had no episodes of acute respiratory insufficiency or myasthenic crises. Although a small reduction in respiratory function during the day off prednisone was seen in some patients, the change was not statistically significant for the group and was probably physiologically unimportant in most patients. The data indicate that in myasthenic patients who have no underlying lung disease respiratory function is not significantly compromised by administering the prednisone on alternate days.