Drugs 2000 Jan; 59 (1): 112-113
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GUEST COMMENTARIES
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per embryo transfer was achieved with a daily in-
jection of 0.25mg (40.3%). GnRH antagonists of-
fer some important clinical advantages. They allow
immediate suppression of LH and a shorter stimu-
lation time when compared to the long agonist pro-
tocol, with lower gonadotrophin consumption and
a lower risk of developing ovarian hyperstimula-
tion syndrome (OHSS). Finally, ovulation can be
induced by means of a GnRH agonist instead of
human chorionic gonadotrophin, thus further re-
ducing the risk of OHSS development. However,
it has not been shown that antagonist protocols re-
sult in superior pregnancy rates compared to stand-
ard long protocols.
In summary, GnRH antagonists provide a clin-
ically well established, short and convenient treat-
ment option, particularly for patients at risk of de-
veloping OHSS or for patients with a poor response
to a standard long protocol. In future studies, an-
tagonists will be used for other gynaecological dis-
orders where ovarian suppression might be useful,
such as endometriosis or myoma of the uterus.
Ganirelix
A Viewpoint by Thomas Strowitzki
Department of Gynecological Endocrinology
and Reproductive Medicine, University of
Heidelberg, Heidelberg, Germany
Ganirelix is 1 of 2 gonadotropin-releasing hor-
mone (GnRH) antagonists now clinically available
(the other is cetrorelix), which has been developed
for the prevention of premature luteinising hor-
mone (LH) surges in women undergoing control-
led ovarian hyperstimulation in combination with
assisted reproductive techniques (ART). The cur-
rent standard protocol in ART cycles combines a
prolonged ovarian suppression with GnRH ago-
nists followed by ovarian stimulation with gonad-
otropins. GnRH agonists act via pituitary receptor
downregulation after an initial release of gonado-
tropins from the pituitary gland (flare-up), result-
ing in pituitary desensitisation. In contrast, GnRH
antagonists block GnRH receptors by competitive
inhibition.
In a dose finding study in in vitro fertilisation
(IVF) cycles only 1 of 69 patients who received a
daily injection of ganirelix 0.25mg showed an LH
rise during treatment.[1] No premature LH rise was
reported in groups who received ganirelix at a daily
dose of at least 0.5mg. The clinical pregnancy rates
were acceptable in groups with a maximum daily
dose of 0.5mg. The highest clinical pregnancy rate
References
1. Mannaerts B, Devroey P, Abyholm T, et al. A double-blind,
randomized, dose-finding study to assess the efficacy of the
gonadotrophin-releasing hormone antagonists ganirelix (Org
37462) to prevent premature luteinizing hormone surges in
women undergoing ovarian stimulation with recombinant fol-
licle stimulating hormone (Puregon). Hum Reprod 1998 Nov;
13: 3023-31
Fredga
