Hormone antagonists aromatase inhibitors

Hormone Antagonists and modulators—includes aromatase inhibitors such as anastrazole... 

Theoretically, the combination of an oestrogen antagonist such as tamoxifen and an aromatase inhibitor should provide additional benefit in the treatment of hormone-dependent cancers, however, no clinical studies have yet found this to be so. The pharmacokinetic interactions described above may partly explain this. It may be preferable to use these drugs sequentially rather than concurrently. ... 

Tamoxifen (Tam) (Novaldex) is an estrogen receptor antagonist present in breast tissue, with activity linked to its metabolite hydroxytamoxifen (OHTam). In other tissues (endometrium) it behaves as an agonist due to the presence of other coactivators. This SERM is involved in the endocrine therapy commonly used with hormone-dependent breast cancers, although aromatase inhibitors (Anastrozole) are also frequently used for the same female patient group. Tamoxifen is the most common hormonal treatment for breast cancer in men. It also protects against osteoporosis [17]. 

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