Sodium aurothiomalate (a.k.a. gold sodium thiomalate, and sold under the brand names Myocrisin, Myochrysine, Aurolate and others) is a gold compound used to reduce the symptoms of Rheumatoid Arthritisplugin-autotooltip__plain plugin-autotooltip_bigRheumatoid Arthritis

Rheumatoid Arthritis (RA) is a chronic severe inflammatory disease believed to affect around 1% of the global population. It primarily affects joints,which typically become warm, swollen,and painful. Pain and stiffness often worsen following rest. Most commonly, the wrists and hands are involved, with the same joints typically involved on both sides of the body.

In the mid 1800's gold salts of various types had been used to try to treat TB - with very little success. Despite their lack of effectiveness and dangerous side effects they were still in used as late as the 1920s, ^{[ * See note 1 below ]}

In 1928 French physician Jaques Forestier began testing gold salts as a possible treatment for rheumatoid arthritis (ref. ^{[ paywalled ]} ) This time there were some positive results - but still with a wide range of severe side-effects - so the drug was usually considered a last-resort measure.

Its precise 'mechanism of action' is unknown, though it has been shown to inhibit the synthesis of prostaglandins (hormone-like lipid compounds), and several important enzymes.

Further details, see: Wikipedia

* Notes :

1) It's puzzling why a TB treatment which had such serious side effects, and which clearly didn't work well, was in use for so long. There are suggestions that it may have had to do with its high cost. In other words manufacturers were keen to keep supplying the expensive drugs, and, additionally, some patients felt reassured that they were getting an exclusive 'gold-standard' treatment.

2) Since the late 2010s, almost all pharmaceutical firms have stopped making the drug, and it's now largely discontinued as a treatment. Research into the drug's effects has also appears to have paused.