A controlled trial of magnesium dithiosalicylate compared with aspirin in rheumatoid arthritis

The anti-inflammamtory effectiveness and side-effects of magnesium dithiosalicylate were compared to aspirin in a 3-month, parallel, double-blind trial in 40 patients suffering from active rheumatoid arthritis. The results showed that 3 g magnesium dithiosalicylate daily had anti-inflammatory properties similar to those of 3 g aspirin daily in rheumatoid arthritis. A statistically significant change in morning stiffness, number of tender joints, pain score and erythrocyte sedimentation rate was observed in the magnesium dithiosalicylate group. In the magnesium dithiosalicylate group, 8 patients had to be withdrawn from the trial because of serious side-effects compared to 5 in the aspirin group. Gastro-intestinal intolerance occurred as frequently in both treatment groups. Hypersensitivity to magnesium dithiosalicylate was a serious problem and the reason for withdrawal in 4 cases. The high frequency of side-effects to magnesium dithiosalicylate makes this drug unacceptable for treatment of rheumatoid arthritis at the present time. Further pharmacological studies might reveal new derivatives which are as effective but with less side-effects. The anti-inflammatory activity of magnesium dithiosalicylate resembled that observed with gold and penicillamine. The fact that all these drugs have a sulphhydril group in common is stressed.