Lasofoxifene-N-oxide

Lasofoxifene-N-oxide is an oxidized derivative of the selective estrogen receptor modulator Lasofoxifene, featuring an N-oxidation event at the pyridine nitrogen of the parent compound’s heterocyclic core. This impurity retains the biphenyl-phenoxyphenyl scaffold but incorporates an oxygen atom in a trigonal pyramidal geometry, altering electronic properties while preserving steric configuration. Its formation arises from oxidative stress during synthetic pathways or storage. This compound serves as a critical HPLC reference standard for quantifying process-related impurities in Lasofoxifene drug substance batches.