New drugs suppress menstruation safely
Two new antiprogestogens have been found to suppress
menstruation safely in animal studies. Antiprogestogens block progesterone
action by binding to the progesterone receptor. The two new anti-progestogens,
ZK137316 and ZK230211, are new generation antiprogestogens that have increased
potency and reduced antiglucocorticoid activity.
Dr Robert Brenner, Oregon Regional Primate Research
Centre, United States, and colleagues studied the effects of the two antiprogestogens
in monkeys. ZK137316 was found to allow ovulation but block menstruation
and ZK230211 to block both ovulation and menstruation. Neither drug suppressed
circulating estradiol concentrations below normal follicular phase concentrations,
suggesting that it is unlikely that they would be associated with symptoms
of oestrogen deprivation, the researchers say. Also, when synthetic oestrogens
are normally given, synthetic progesterones are needed in addition to
prevent the unopposed actions of oestrogens on the endometrium. However,
this may not be needed with the new antiprogesterones because they have
endometrial antiproliferative effects, the researchers say.
In a press statement, Dr Bremner emphasised that
the drugs were not solely important for lifestyle choice but also had
potential to bring relief to women with endometriosis and painful and
excessive monthly bleeding. “It is possible to use the oral contraceptive
pill without the pill-free interval for this purpose, but not all women
can tolerate the pill,” he added (Human Reproduction 2001;16:1562).
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