Letrozole is a novel and potent type (II) aromatase inhibitor with IC50 of 11.5 nM. It belongs to the reversible non-steroidal compound family which can inhibit Arom. However, there is no evidence that it can affect the adrenal steroidogenesis.
Normally, Type II inhibitors have a common feature of heterocyclic azole moiety, which can be binded to the heme–iron in aromatase. It contains a structure of 1,2,4-triazole moieties which can coordinate the heme–iron of cytochrome P450. Meanwhile, benzonitrile substituted letrozole can mimic a unique enzyme structure of the substrate androstenedione.
Letrozole administration can reduce spine synapse and axon outgrowth and it also will decrease the expression of estrogen receptor (ER). While, the synaptic proteins including GAP-43 can impaire the long-termpotentiation. Letrozole is proved to promote FSH release from the hypothalamic pituitary axis by responding to decreased estrogen (E) feedback.
 Chen Bian, Yangang Zhao, Qiang Guo, Ying Xiong, Wenqin Cai, Jiqiang Zhang. Aromatase inhibitor letrozole downregulates steroid receptor coactivator-1 in specific brain regions that primarily related to memory, neuroendocrine and integration. The Journal of Steroid Biochemistry and Molecular Biology. May 2014. 141: 37-43.
 Hakki Türker Akçay, Riza Bayrak. Computational studies on the anastrozole and letrozole, effective chemotherapy drugs against breast cancer. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 25 March 2014. 122: 142-152.
 Lindsay Malloch, Alice Rhoton-Vlasak. An assessment of current clinical attitudes toward letrozole use in reproductive endocrinology practices. Fertility and Sterility. December 2013. 100(6): 1740-1744.