Oxyphenbutazone (OPB)

Oxyphenbutazone is a non-steroidal anti-inflammatory drug (NSAID). It is a metabolite of phenylbutazone. Interference or "masking" in thin layer chromatography occurs when the presence of one drug on a thin layer plate physically obscures or interferes with the detection of another drug. Of 20 acidic drugs called "positive" since 1981 by laboratories affiliated with the Association of Official Racing Chemists, 16 did not comigrate with phenylbutazone or oxyphenbutazone and could not, therefore, be masked by these agents. Three medications (diclofenac, fenoprofen, ibuprofen) were potentially masked by phenylbutazone and one (sulindac) was potentially masked by oxyphenbutazone. The word oxyphenbutazone is part of the single play yielding the highest possible score under American tournament Scrabble rules, scoring 1,780 points across three triple-word-score squares, joining seven tiles to eight already-played tiles.