Oxyphenbutazone
Oxyphenbutazone is a nonsteroidal anti-inflammatory drug (NSAID). It is a metabolite of phenylbutazone. It was withdrawn from markets worldwide in mid-1980s due to bone marrow suppression and the risk of Stevens–Johnson syndrome. The word "oxyphenbutazone" is theoretically the highest-scoring Scrabble move known with 1,780 points, but playing the word would require extremely unlikely circumstances. (TWL06 dictionary)

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Nonsteroidal anti-inflammatory drugs
Pyrazolidindiones
Phenols
Withdrawn drugs