A selective progesterone receptor modulator (SPRM) is an agent that acts on the progesterone receptor. A characteristic that distinguishes such a substances from receptor agonists and antagonists is that their action is different for various tissues, thereby granting the possibility to selectively inhibit or stimulate progesterone-like action in various tissues.

Members

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Members are:

• RU 486, also mifepristone
• Progenta, also CDB 4124, or Proellex
• Asoprisnil

Uses

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SPRMs are in limited use:

• RU 486 is used as an abortifacient.
• Progenta and Asoprisnil are under investigation (2005) for the medical treatment of uterine leiomyoma.

Method of action

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Although the SPRMs have no immediate structural relationship with progesterone, they are stereochemically similar to this hormone and interact with its receptors.

There are three types of progesterone receptors which are intracellular: α (α homodimer), β (β homodimer) and αβ (α- and β-receptor heterodimer). Different tissues have more or less of each class. In turn, each SPRM has more affinity to one and less to the other receptor isoform. Genes activated or suppressed by progesterone receptors generally have a progesterone response element sequence in their promotor.

See also

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Selective estrogen receptor modulator

hormonal agents