Jehonathan Pinthus and colleagues presented research in animal models, suggesting possible differences between surgical castration, a GnRH antagonist
(degarelix) and a GnRH analogue (enantone) with respect to weight gain, development of the metabolic syndrome, and atherosclerosis.[sup.3] The hypothesis was that GnRH antagonists
, which maximally inhibit follicle-stimulating hormone (FSH) levels, would be associated with reduced adiposity, the development of metabolic syndrome and CV disease compared to GnRH analogues and orchiectomy.
The introduction of newer GnRH analogues, the GnRH antagonists
, created the potential for milder stimulation protocols that are better tolerated and less costly, have a quicker onset of action, result in a lower incidence of luteinising hormone (LH) surge, and are associated with a lower multiple pregnancy rate.
Klotz said: "More than 2,000 patients have now taken part in clinical trials for degarelix and there have been no signs of immediate or late-onset systemic allergic reactions, in contrast to other reported trials of other GnRH antagonists
Lamvu said she is most optimistic about the potential for new GnRH antagonists
to make a significant improvement in chronic pelvic pain associated with endometriosis.
In the antagonist protocol, FSH analogues were started at the beginning of the follicular phase of the cycle, and GnRH antagonists
were added when the leading follicles reached 12-13 mm in diameter.
Refinement in GnRH antagonists
continued after 1984, initially hampered by histamine release side-effects, which were overcome in 1994 with the third-generation GnRH antagonists
that are currently in clinical use but still under assessment with regard to efficacy.
Another advance involves GnRH antagonists
for controlled ovarian hyperstimulation for IVF.
have a relatively weaker binding affinity to GnRH receptors than that of GnRH agonists.
New forms of GnRH antagonists
under development are likely to be far more effective, he said.
reported stimulation of poor responders by a combination of gonadotropins, clomiphene citrate, and multiple flexible GnRH antagonists
Comparison of preovulatory follicular concentrations of epidermal growth factor, insulin-like growth factor-I, and inhibins A and B in women undergoing assisted conception treatment with gonadotropin-releasing hormone (GnRH) agonists and GnRH antagonists
. Fertil Steril.
Although use of GnRH antagonists
in some controlled clinical trials showed that the frequency of the severe form of OHSS is lower than in case when agonists are used, one cannot exclude a probability that such results are a consequence of possibility that agonists are often used instead of hCG in protocols with antagonists as ovulation triggers, which may itself reduce incidence of OHSS.21 However, patient's predisposition for developing OHSS is still considered as the most probable factor which is also in line with our results.