Goserelin acetate, like leuprolide acetate, is a synthetic superagonist nonapeptide analogue of
GnRH that possesses greater potency than the natural hormone. Note that it contains D-Ser(But)
and NH-NHCONH2 in place of Gly6 and Gly10-NH2, respectively. That is, the C terminal modification simply has an NH substituting for the CH2 of Gly, and like the C-terminal
change in leuprolide acetate, this inhibits enzymatic degradation of the peptide by the
postproline carboxyamide peptidase.
Goserelin acetate is available in the form of a small, solid pellet that is administered as an SC
implant for the palliative treatment of advanced, metastatic breast cancer in pre- and
perimenopausal women or, similarly, as a palliative in advanced prostatic cancer. The rationale
for this drug's use is, as described above, its ability as a superagonist to bring the levels of
estradiol or testosterone to near castrate levels, thus slowing the progression of breast or
prostate carcinoma, respectively. Additionally, goserelin acetate is approved for use in treating
endometriosis for up to 6 months.
