Ulipristal acetate, sold under the brand name Ella among others, is a

medication Medication (also called medicament, medicine, pharmaceutical drug, medicinal product, medicinal drug or simply drug) is a drug used to medical diagnosis, diagnose, cure, treat, or preventive medicine, prevent disease. Drug therapy (pharmaco ...

used for

emergency contraception Emergency contraception (EC) is a birth control measure, used after sexual intercourse to prevent pregnancy. There are different forms of EC. Emergency contraceptive pills (ECPs), sometimes simply referred to as emergency contraceptives (ECs), ...

(birth control) and

uterine fibroids Uterine fibroids, also known as uterine leiomyomas, fibromyoma or fibroids, are leiomyoma, benign smooth muscle tumors of the uterus, part of the female reproductive system. Most people with fibroids have no symptoms while others may have dysm ...

. As emergency contraception it should be used within 120 hours of vaginally penetrating intercourse. For fibroids it may be taken for up to six months. It is taken

by mouth Oral administration is a route of administration whereby a substance is taken through the Human mouth, mouth, swallowed, and then processed via the digestive system. This is a common route of administration for many medications. Oral administ ...

. Common side effects include headache, nausea, feeling tired, and abdominal pain. It should not be used in women who are already

pregnant Pregnancy is the time during which one or more offspring gestation, gestates inside a woman's uterus. A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Conception (biology), Conception usually occurs ...

. It is in the

selective progesterone receptor modulator A selective progesterone receptor modulator (SPRM) is an agent that acts on the progesterone receptor (PR), the biological target of progestogens like progesterone. A characteristic that distinguishes such substances from full receptor agonists ...

(SPRM) class of medications. It works by preventing the effects of

progesterone Progesterone (; P4) is an endogenous steroid and progestogen sex hormone involved in the menstrual cycle, pregnancy, and embryogenesis of humans and other species. It belongs to a group of steroid hormones called the progestogens and is the ma ...

, therefore preventing

ovulation Ovulation is an important part of the menstrual cycle in female vertebrates where the egg cells are released from the ovaries as part of the ovarian cycle. In female humans ovulation typically occurs near the midpoint in the menstrual cycle and ...

but not affecting

fertilization Fertilisation or fertilization (see American and British English spelling differences#-ise, -ize (-isation, -ization), spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give ...

or implantation. Ulipristal acetate was approved for medical use in the United States in 2010. It is on the

World Health Organization's List of Essential Medicines The WHO Model List of Essential Medicines (aka Essential Medicines List or EML), published by the World Health Organization (WHO), contains the medications considered to be most effective and safe to meet the most important needs in a health s ...

Medical uses

Emergency contraception

For

a 30 mg tablet is used within 120 hours (5 days) after unprotected intercourse or contraceptive failure. It has been shown to prevent about 62–85% of expected pregnancies, and prevents more pregnancies than emergency contraception with

levonorgestrel Levonorgestrel is a hormonal medication used in a number of birth control methods. It is combined with an estrogen to make combination birth control pills. As an emergency birth control, sold under the brand names Plan B One-Step and Julie, ...

. Ulipristal acetate is available by prescription for emergency contraception in over 50 countries, with access through pharmacists without a prescription being tested in the United Kingdom. In November 2014, the

European Medicines Agency The European Medicines Agency (EMA) is an agency of the European Union (EU) in charge of the evaluation and supervision of pharmaceutical products. Prior to 2004, it was known as the European Agency for the Evaluation of Medicinal Products ...

(EMA) recommended availability of ellaOne emergency contraceptive without prescription in the European Union. In January 2015 the

European Commission The European Commission (EC) is the primary Executive (government), executive arm of the European Union (EU). It operates as a cabinet government, with a number of European Commissioner, members of the Commission (directorial system, informall ...

issued an implementing decision amending accordingly the marketing authorization of EllaOne in the EU. Since July 2016, it is available without prescription in Israel.

Uterine fibroids

Ulipristal acetate is used for pre-operative treatment of moderate to severe symptoms of

in adult women of reproductive age. The use of ulipristal acetate to treat fibroids was suspended in the European Union in March 2020. In November 2020, the

Committee for Medicinal Products for Human Use The Committee for Medicinal Products for Human Use (CHMP), formerly known as the Committee for Proprietary Medicinal Products (CPMP), is the European Medicines Agency's committee responsible for elaborating the agency's opinions on all issues regar ...

(CHMP) of the

(EMA) recommended that ulipristal acetate be used only to treat uterine fibroids in premenopausal women for whom surgical procedures (including uterine fibroid embolization) are not appropriate or have not worked. Text was copied from this source which is copyright European Medicines Agency. Reproduction is authorized provided the source is acknowledged. In addition, the committee stated that ulipristal acetate must not be used for controlling symptoms of uterine fibroids while awaiting surgical treatment. Treatment of uterine fibroids with ulipristal acetate for 13 weeks effectively controlled excessive bleeding due to uterine fibroids and reduced the size of the fibroids. Two intermittent 3-months treatment courses of ulipristal acetate 10 mg resulted in amenorrhea at the end of the first treatment course in 79.5%, at the end of the second course in 88.5% of subjects. Mean myoma volume reduction observed during the first treatment course (−41.9%) was maintained during the second one (−43.7%). After two to four 3-months courses of treatment, UPA-treated fibroids shown about -70% in volume reduction. Volume reduction of uterine fibroid induced by ulipristal acetate was tentatively explained by the combination of multifactorial events involving control of proliferation of the tumor cells, induction of

apoptosis Apoptosis (from ) is a form of programmed cell death that occurs in multicellular organisms and in some eukaryotic, single-celled microorganisms such as yeast. Biochemistry, Biochemical events lead to characteristic cell changes (Morphology (biol ...

and remodeling of the

extracellular matrix In biology, the extracellular matrix (ECM), also called intercellular matrix (ICM), is a network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide structural and bio ...

under the action of

matrix metalloproteinase Matrix metalloproteinases (MMPs), also known as matrix metallopeptidases or matrixins, are metalloproteinases that are calcium-dependent zinc-containing endopeptidases; other family members are adamalysins, serralysins, and astacins. The MMPs be ...

s. In May 2018, the

(EMA) recommended measures to minimize the risk of rare but serious liver injury with ulipristal, including contraindication in women with known liver problems; liver tests before, during and after stopping treatment; a card for women to inform them about the need for liver monitoring and to contact their doctor should they develop symptoms of liver injury. In addition, use of the medicine for more than one treatment course has been restricted to women who are not eligible for surgery.

Abortion

A 2025 preliminary clinical study on 133 pregnant women indicated the possibility that ulipristal acetate, at a substantially higher dose than used for contraception and combined with

misoprostol Misoprostol is a synthetic prostaglandin medication used to prevent and treat stomach and duodenal ulcers, induce labor, cause an abortion, and treat postpartum bleeding due to poor contraction of the uterus. It is taken by mouth when used ...

, could be used as a more widely available and similarly effective substitute for the

abortifacient An abortifacient ("that which will cause a miscarriage" from Latin: '' abortus'' "miscarriage" and '' faciens'' "making") is a substance that induces abortion. This is a nonspecific term which may refer to any number of substances or medications, ...

mifepristone Mifepristone, and also known by its developmental code name RU-486, is a drug typically used in combination with misoprostol to bring about a medical abortion during pregnancy. This combination is 97% effective during the first 63 days (9 wee ...

Contraindications

Ulipristal acetate should not be taken by women with severe liver diseases because of its CYP mediated metabolism. It has not been studied in women under the age of 18. It is also not recommended for women with severe asthma receiving

glucocorticoid Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebra ...

treatment because it has shown antiglucocorticoid effects in animal studies.

Pregnancy

Unlike levonorgestrel, and like

, ulipristal acetate is

embryotoxic Teratology is the study of abnormalities of physiological development in organisms during their life span. It is a sub-discipline in medical genetics which focuses on the classification of congenital abnormalities in dysmorphology caused by ...

in animal studies. Before taking the drug, a pregnancy must be excluded. The EMA proposed to avoid any allusion to a possible use as an

in the package insert to avert

off-label use Off-label use is the use of pharmaceutical drugs for an unapproved indication or in an unapproved age group, dosage, or route of administration. Both prescription drugs and over-the-counter drugs (OTCs) can be used in off-label ways, although mo ...

. Prior to the 2025 study mentioned above, it was considered unlikely that ulipristal acetate could effectively be used as an abortifacient, since it is used in much lower doses (30 mg) than the roughly equipotent mifepristone (600 mg), and since mifepristone has to be combined with a

prostaglandin Prostaglandins (PG) are a group of physiology, physiologically active lipid compounds called eicosanoids that have diverse hormone-like effects in animals. Prostaglandins have been found in almost every Tissue (biology), tissue in humans and ot ...

for the induction of abortion. However, data on embryotoxicity in humans are very limited, and it is not clear what the risk for an abortion or for teratogenicity (birth defects) is. Of the 29 women studied who became pregnant despite taking ulipristal acetate, 16 had induced abortions, six had spontaneous abortions, six continued the pregnancies, and one was

lost to follow-up In the clinical research trial industry, lost to follow-up refers to patients who at one point in time were actively participating in a clinical research trial, but have become lost (either by error in a computer tracking system or by being unrea ...

Lactation

It is not recommended to breast feed within seven days of taking the drug since ulipristal acetate is excreted into the breast milk, and possible effects on the infant have not been studied.

Side effects

The most common side effects include headache, nausea (feeling sick), abdominal pain (stomach ache), and dysmenorrhea (period pains).

Interactions

Ulipristal acetate is metabolized by CYP3A4 in vitro. Ulipristal acetate is likely to interact with substrates of CYP3A4, like

rifampicin Rifampicin, also known as rifampin, is an ansamycin antibiotic used to treat several types of bacterial infections, including tuberculosis (TB), ''Mycobacterium avium'' complex, leprosy, and Legionnaires' disease. It is almost always used tog ...

phenytoin Phenytoin (PHT), sold under the brand name Dilantin among others, is an anticonvulsant, anti-seizure medication. It is useful for the prevention of tonic-clonic seizures (also known as grand mal seizures) and focal seizures, but not absence se ...

St John's wort ''Hypericum perforatum'', commonly known as St. John's wort (sometimes perforate St. John's wort or common St. John's wort), is a flowering plant in the family Hypericaceae. It is a hairless, perennial herb with woody roots, yellow flowers ma ...

carbamazepine Carbamazepine, sold under the brand name Tegretol among others, is an anticonvulsant medication used in the treatment of epilepsy and neuropathic pain. It is used as an adjunctive treatment in schizophrenia along with other medications and as ...

ritonavir Ritonavir, sold under the brand name Norvir, is an antiretroviral medication used along with other medications to treat HIV/AIDS. This combination treatment is known as highly active antiretroviral therapy (HAART). Ritonavir is a protease inhi ...

, therefore concomitant use with these agents is not recommended. It might also interact with hormonal contraceptives and

progestogens Progestogens, also sometimes written progestins, progestagens or gestagens, are a class of natural or synthetic steroid hormones that bind to and activate the progesterone receptors (PR). Progesterone is the major and most important progestogen ...

such as

and other substrates of the progesterone receptor, as well as with

glucocorticoids Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebra ...

Pharmacology

Pharmacodynamics

As an SPRM, ulipristal acetate has

partial agonist In pharmacology, partial agonists are drugs that bind to and activate a given Receptor (biochemistry), receptor, but have only partial Intrinsic activity, efficacy at the receptor relative to a full agonist. They may also be considered Ligand (bio ...

ic as well as antagonistic effects on the

progesterone receptor The progesterone receptor (PR), also known as NR3C3 or nuclear receptor subfamily 3, group C, member 3, is a protein found inside cells. It is activated by the steroid hormone progesterone. In humans, PR is encoded by a single ''PGR'' gene resi ...

. Ulipristal acetate exhibits similar potency to antagonize

''in vitro''. It also binds to the

androgen receptor The androgen receptor (AR), also known as NR3C4 (nuclear receptor subfamily 3, group C, member 4), is a type of nuclear receptor that is activated by binding any of the androgenic hormones, including testosterone and dihydrotestosterone, in th ...

and the

glucocorticoid receptor The glucocorticoid receptor (GR or GCR) also known by its gene name ''NR3C1'' ( nuclear receptor subfamily 3, group C, member 1) is the steroid receptor for glucocorticoids such as cortisol. The GR is expressed in almost every cell in the bod ...

, but is only a weak

antiandrogen Antiandrogens, also known as androgen antagonists or testosterone blockers, are a class of drugs that prevent androgens like testosterone and dihydrotestosterone (DHT) from mediating their biological effects in the body. They act by blocking t ...

and

antiglucocorticoid Antiglucocorticoid drugs are a class of medications that act to reduce the effects of glucocorticoids, primarily cortisol, in the body. They include direct glucocorticoid receptor antagonists such as mifepristone and synthesis inhibitors such as ...

relative to

flutamide Flutamide, sold under the brand name Eulexin among others, is a nonsteroidal antiandrogen (NSAA) which is used primarily to treat prostate cancer. It is also used in the treatment of androgen-dependent conditions like acne, hirsutism, excessive ...

and

, respectively. Ulipristal acetate has no relevant

affinity Affinity may refer to: Commerce, finance and law * Affinity (law), kinship by marriage * Affinity analysis, a market research and business management technique * Affinity Credit Union, a Saskatchewan-based credit union * Affinity Equity Pa ...

to the

estrogen Estrogen (also spelled oestrogen in British English; see spelling differences) is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three ...

and

mineralocorticoid receptor The mineralocorticoid receptor (or MR, MLR, MCR), also known as the aldosterone receptor or nuclear receptor subfamily 3, group C, member 2, (NR3C2) is a protein that in humans is encoded by the ''NR3C2'' gene that is located on chromosome 4q31 ...

s. Phase II

clinical trial Clinical trials are prospective biomedical or behavioral research studies on human subject research, human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel v ...

s suggest that the mechanism might consist of blocking or delaying

and of delaying the maturation of the

endometrium The endometrium is the inner epithelium, epithelial layer, along with its mucous membrane, of the mammalian uterus. It has a basal layer and a functional layer: the basal layer contains stem cells which regenerate the functional layer. The funct ...

Pharmacokinetics

In animal studies, the drug was quickly and nearly completely absorbed from the gut. Intake of food delays absorption, but it is not known whether this is clinically relevant. Ulipristal acetate is

metabolized Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the co ...

in the

liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...

, most likely by

CYP3A4 Cytochrome P450 3A4 (abbreviated CYP3A4) () is an important enzyme in the body, mainly found in the liver and in the intestine, which in humans is encoded by ''CYP3A4'' gene. It organic redox reaction, oxidizes small foreign organic molecules ( ...

, and to a small extent by

CYP1A2 Cytochrome P450 1A2 (abbreviated CYP1A2), a member of the cytochrome P450 mixed-function oxidase system, is involved in the metabolism of xenobiotics in the human body. In humans, the CYP1A2 enzyme is encoded by the ''CYP1A2'' gene. Function ...

and

CYP2D6 Cytochrome P450 2D6 (CYP2D6) is an enzyme that in humans is encoded by the ''CYP2D6'' gene. ''CYP2D6'' is primarily expressed in the liver. It is also highly expressed in areas of the central nervous system, including the substantia nigra. CYP2 ...

. The two main

metabolite In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...

s have been shown to be pharmacologically active, but less than the original drug. The main

excretion Excretion is elimination of metabolic waste, which is an essential process in all organisms. In vertebrates, this is primarily carried out by the lungs, Kidney (vertebrates), kidneys, and skin. This is in contrast with secretion, where the substa ...

route is via the

feces Feces (also known as faeces American and British English spelling differences#ae and oe, or fæces; : faex) are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the ...

History

Ulipristal acetate was granted marketing authorization by the

(EMA) in May 2009. In 2014, the EMA recommended ulipristal be made available without a prescription in the European Union. The U.S.

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respo ...

(FDA) approved the drug for use in the United States on 13 August 2010, following the FDA advisory committee's recommendation. Watson Pharmaceuticals announced the availability of ulipristal acetate in the United States on 1 December 2010, in retail pharmacies, clinics, and one on-line pharmacy, KwikMed.

Society and culture

Brand names

Ulipristal acetate is marketed as an emergency contraceptive (30 mg) in over 75 countries, under different brands such as ella, ellaOne, Dvella, FemelleOne, Femke, Lencya, Prevent One, ulip, Ulipristal Stada, Ulipristal Mylan, Ulipristal acetate Sandoz and others. Ulipristal acetate is also marketed for treatment of uterine firboids, under different brands such as Esmya or Primette.

References

{{DEFAULTSORT:Ulipristal Acetate Acetate esters Dimethylamino compounds Antiprogestogens Antiglucocorticoids Embryotoxicants Conjugated dienes Diketones Hormonal contraception Norpregnanes Selective progesterone receptor modulators World Health Organization essential medicines Wikipedia medicine articles ready to translate Enones