Rifamycin SV in the Treatment of Knee Synovitis.

Rifamycin SV, injected intraarticularly at dosages of 500 mg weekly, induced a complete removal of persistent knee effusions in 57 of 60 rheumatoid patients, and in all patients with effusions due to juvenile rheumatoid arthritis (three), ankylosing spondylitis (three), psoriatic arthritis (10), intermittent hydrarthrosis (two) and chondromatosis (two). One rheumatoid patient did not respond to treatment, and two dropped out because of local side effects. The number of infiltrations varied between three and 12, and was correlated with activity grade of local synovitis (P < .05). As of this writing, 50 out of 57 rheumatoid patients and 19 out of 20 belonging to the other groups have not had a relapse of effusions after 25 to 36 months and 12 to 20 months respectively. While the changes in the synovial fluid and membrane of the rheumatoid subjects, and the results obtained from experimental arthritis in guinea pigs, confirm the hypothesis that Rifamycin has a local antiinflammatory action in arthritic knee joints, they also suggest that this property alone of the drug is not entirely responsible for its therapeutic action.