1.   He also says chemicals that block hormones may cancel the effect of those that mimic them just as bases neutralize acids.

2.   Mifeprex blocks a hormone that is needed for a pregnancy to continue.

3.   Men with metastatic prostate cancer who have been surgically castrated are sometimes given the drug flutamide to block a hormone that can drive the cancer.

4.   Chemotherapy is a cocktail of cell-killing drugs, and tamoxifen and other hormonal drugs block hormones from nurturing the cancer.

5.   Now, however, they are finding that blocking this hormone actually makes the heart improve.

6.   Still, several major pharmaceutical companies are trying to develop drugs to block the hormone, Cummings said.

7.   Tamoxifen attacks spreading cancer by blocking these hormones.

8.   The pill blocks a hormone, progesterone, that is essential to sustaining pregnancy.

9.   The pill, which will be sold under the brand name Mifeprex, blocks a hormone vital to sustaining a pregnancy.

10.   Women swallow mifepristone, which blocks a hormone essential for maintaining pregnancy.