Clinical pharmacology of polyestradiol phosphate

The results of the present studies demonstrate that intramuscular injections of polyestradiol phosphate (PEP) produce not only considerably increased estrogen concentration in plasma but also maintain the same estrone/estradiol ratio as in normal men. Monthly injections of PEP produce persistent elevation of the plasma estradiol levels throughout the dose interval, and rising PEP doses produce proportionately increasing steady-state plasma concentrations of estradiol. The steady-state plasma concentrations of testosterone are reduced to 45, 25, and 15% of the pretreatment concentrations after treatment every fourth week with 80, 160, and 240 mg PEP, respectively.