The importance of progesterone in myoma pathogenesis explains the effectiveness of MSRP treatment. Clinical and biochemical evidence indicates that MSRPs can reduce myoma growth and improve symptoms (31).

A Cochrane review and meta-analysis evaluated three MSRPs: mifepristone, ulipristal acetate, and asoprisnil (31). Comparing these drugs with placebo showed that MSRPs produced improvements in fibroid symptom severity and quality of life in addition to reduced menstrual blood loss and higher rates of amenorrhea. They also compared MSRP with leuprolide acetate without finding evidence indicating a difference between the two groups for improvement in quality of life and pelvic pain. Regarding adverse effects, MSRPs were associated with endometrial changes which are benign, not related to cancer, and not precancerous (31).

One study evaluated the impact of ulipristal acetate used 2 months before hysteroscopic myomectomy (32). They showed that patients who received this preoperative management had significantly shorter operative times and significantly reduced fluid absorption compared to no preoperative medical treatment (32). It has been shown that ulipristal acetate presents a risk of hepatotoxicity and should therefore be administered with caution (3).

An in vitro study was carried out to determine the cell viability of myomas; in comparison to leuprolide acetate and raloxifene, mifepristone showed the most significant reduction in the viability of fibroid cells (33). Mifepristone in doses of 10 to 25mg causes symptomatic relief with a reduction of more than 90% of menstrual bleeding, 90 to 95% of patients developed amenorrhea which was reversible, the reduction of myoma size occurs with the highest dose (34).