clomifene

Last reviewed 01/2018

• Clomifene binds to oestrogen receptors in the hypothalamus but does not activate them. It therefore blocks the binding of oestradiol and thus prevents negative feedback inhibition of FSH secretion
• the action of clomifene results in greater stimulation of ovarian follicles via increased FSH
  • when a woman is being treated with clomifene then ultrasound monitoring should be used to identify whether the woman has produced a dominant follicle, an indicator of likely ovulation. Serum progesterone concentrations can also be used to help confirm ovulation, and also LH concentrations, because clomifene can cause an exaggerated secretion of LH in the mid-follicular phase, an effect associated with a reduced chance of conception (because it changes the consistency of cervical mucus)
• there is an increased incidence of multiple ovulation with the use of clomifene
• clomifene must be used with caution in cases of polycystic ovarian syndrome

There have been concerns that multiple courses of clomifene therapy (12 or more treatment cycles) may increase the risk of ovarian cancer (1).

As regards the number of clomifene cycles:

• the SPC recommends that women receive no more than around 6 treatment cycles
• however, NICE recommends that there may be clinical benefit in using up to 12 cycles in some women (1) - this reflects that the cumulative pregnancy rate continues to increase with use of up to 10-12 cycles of clomifene treatment

The summary of product characteristics must be consulted before prescribing this drug.

Reference:

1. Drug and Therapeutics Bulletin (2004); 42(4):28-32.