Clomid/Nolva
Clomid (Clomiphene citrate) and Nolva (Nolvadex, Tamoxifen) are structurally similar and classified as selective modulators of estrogen receptors with mixed agonistic and antagonistic properties.
Both drugs are usually used by athletes on Post Cycle Therapy in order to block the receptors of estrogen in the pituitary and ovaries and restore natural testosterone levels.