Over-inhibition of 5AR results in increased availability of testosterone, which may be shunted, via aromatase, to estradiol, causing “feminization,” ., gynecomastia, one of the side effects of 5AR inhibitor drugs; and decreased production of not only 5α-DHT, but its metabolites, 5α-Androstane-3α-17β-diol ( aka 3α-adiol, a storage form of 5α-DHT), and 5α-Androstane-3β-17β-diol ( aka 3β-adiol), an estrogen receptor beta (ERβ) ligand that promotes normal cellular differentiation, thus lessening risk of benign prostatic hypertrophy and prostate cancer. 22 , 23 , 24
The pregnancy rate (Pearl Index [PI] ) in women 18 to 35 years of age was 2. 92 pregnancies per 100 women-years of use (95 percent confidence interval – ) , based on 28 pregnancies that occurred after the onset of treatment and extending through the 7 days following the last dose of Lo Loestrin Fe. Cycles in which conception did not occur, but which included the use of backup contraception, were not included in the calculation of the PI. The PI includes women who did not take the drug correctly.