Between 1958 and 1962, physicians Olive W. Smith, George V. Smith, and Robert W. Kistner performed experiments that demonstrated the effects of the drugs MER-25 and clomiphene citrate on the female human body. MER-25 and clomiphene citrate are drugs that affect estrogen production in women. At the time of the experiment, researchers did not know which organ or organs the drugs affected, the ovaries and/or the anterior pituitary gland. To determine that, the physicians reviewed nine of their own previous studies in women in which they measured the urinary output of hormones after the administration of either drug. Based on their examination the researchers concluded that MER-25 appeared to influence the anterior pituitary gland in the brain to produce a response in the ovaries and that clomiphene citrate appeared to act on the ovaries. Their results provided early evidence about the mechanisms of both drugs. Later, clomiphene citrate became a common fertility drug.