Ovulation Iinduction
Ovulation may be induced by the use of
drugs such as clomiphene citrate, or follicle stimulating
hormone (FSH).
"During clomiphene administration, circulating levels
of FSH and LH rise. The subsequent ovulation that occurs
after clomiphene therapy is a manifestation of the hormone
and morphologic changes produced by the growing follicles.
Clomiphene therapy does not directly stimulate ovulation,
but it retrieves and magnifies the sequence of events that
are the physiologic features of a normal cycle. The effectiveness
of the drug, however, may not be restricted to its ability
to cause an appropriate GnRH discharge."
(Excerpts from: Clinical Gynecologic Endocrinology and Infertility.
Speroff, Glass, and Kase. Lippincott Williams & Wilkins.
1999)
"Recombinant FSH (recFSH) has now become available
for clinical work.
"When used for ovarian stimulation, recFSH compares
favorably with urinary gonadotropins. This advantage is
conferred by its high purity, high specific activity, absence
of biological contamination and lack of contaminating LH
activity. RecFSH is safe and well tolerated; its elimination
half-life resembles that of urinary FSH.
"RecFSH has been used for IVF. It led to multiple follicle
growth as well as the same mean number of oocytes, fertilization
and pregnancies as obtained with urinary FSH. It is safe
and effective. Its efficiency was assessed in a European
multicentric trial involving 1000 women undergoing IVF.
Pregnancy rates were 22% with recFSH and 18% with urinary
FSH (uFSH). More oocytes were recovered from patients treated
with recFSH, and the number of dominant follicles, preovulatory
levels of estradiol and number of embryos were all higher
with recFSH.
"RecFSH could offer advantages for ovarian stimulation.
Any clarification of the roles of its various isoforms could
improve its efficiency. The lack of any LH response could
help in averting the occurrence of high tonic LH levels.
Whether it will displace hMG in terms of efficiency and
cost remains to be seen."
(Excerpts from: Principles and Practice of Assisted Human
Reproduction. Edwards and Brody. W.B Saunders Company, 1995)
