Table I.

Medications that result in leiomyoma shrinkage and their effects in women.

Class	Examples	Mechanism of action	Side effects	Pregnancy category	FDA approved for leiomyoma	Tumors recur after cessation	Comments
GnRH agonists	Leuprolide, Triptorelin	Abolishes GnRH pulsatility	Menopausal symptoms, bone loss	X	Yes, leuprolide for preoperative anemia only	Yes	Initial flare effect; Requires add-back therapy after 6 months
GnRH antagonists	Ganirelix, Elagolix	Competitive inhibition of GnRH	Menopausal symptoms, bone loss	X	No	Yes	Avoids flare effect of GnRH agonists; Elagolix is the only oral GnRH antagonist
SPRMs	Ulipristal, Mifepristone	Varied progesterone antagonism	Endometrial thickening/hyperplasia	X	No	Yes
Aromatase inhibitors	Letrozole, Anastrozole	Competitive inhibition of the aromatase enzyme	Bone loss	D	No	Yes	Can cause follicular stimulation

FDA, Food and Drug Administration.

Pregnancy categories are based on FDA classifications (A–D, X), D = established evidence of fetal risk, but potential benefits may outweigh risks in select patients; X = established evidence of fetal risk, with risks of use in pregnant women clearly outweighing the benefits.