Lactones
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Cyclic esters of hydroxy carboxylic acids, containing a 1-oxacycloalkan-2-one structure. Large cyclic lactones of over a dozen atoms are MACROLIDES.  pyran-2-ones: index PYRONES + LACTONES but BENZOPYRAN-2-ONES is available; for cyclic lactones over 12 atoms consider MACROLIDES   
SubstanceCAS Registry & nameCategoriesSourceDrugs*
rofecoxib [ MK 0966,MK-0966,Vioxx,MK 966,MK-966,refecoxib,Cahill May Roberts brand of rofecoxib,Merck brand of rofecoxib,Merck Frosst brand of rofecoxib,Merck Sharp & Dhome brand of rofecoxib,MSD brand of rofecoxib,Vioxx Dolor ] 0 4-(4-methylsulfonylphenyl)-3-phenyl-5H-furan-2-one  *Lactones*Sulfones
Pharma Action Cyclooxygenase 2 Inhibitors
Lancet 1999 Jan 23;353(9149):307-14 VIOXX