chemistry

Ulipristal acetate

Ulipristal acetate is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Ulipristal acetate rather than just read about it. In short: Ulipristal acetate, sold under the brand name Ella among others, is a medication used for emergency contraception (birth control) and uterine fibroids. As emergency contraception it should be used within 120 hours of vaginally penetrating intercourse.

Key takeaways

Ulipristal acetate belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Ulipristal acetate to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Ulipristal acetate from memory before moving on to harder problems.

Reference excerpt

Ulipristal acetate, sold under the brand name Ella among others, is a medication used for emergency contraception (birth control) and uterine fibroids. 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. Common side effects include headache, nausea, feeling tired, and abdominal pain. It should not be used in women who are already pregnant. It is in the selective progesterone receptor modulator (SPRM) class of medications. It works by preventing the effects of progesterone, therefore preventing ovulation but not affecting fertilization 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.

Medical uses

Emergency contraception For emergency contraception 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. 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 (EMA) recommended availability of ellaOne emergency contraceptive without prescription in the European Union. In January 2015 the European Commission 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 uterine fibroids 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 (CHMP) of the European Medicines Agency (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. 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 and remodeling of the extracellular matrix under the action of matrix metalloproteinases. In May 2018, the European Medicines Agency (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. There is currently no consistent or convincing evidence that ulipristal acetate at the emergency contraceptive dose causes clinically meaningful changes in endometrial gene expression that would affect endometrial receptivity or prevent implantation. There is limited but emerging evidence suggesting ulipristal acetate (UPA) is associated with favorable pregnancy outcomes—including successful full-term pregnancies—when used to treat uterine fibroids in women with prior miscarriage history.

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

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 treatment because it has shown antiglucocorticoid effects in animal studies.

Pregnancy Unlike levonorgestrel, and like mifepristone, ulipristal acetate is embryotoxic 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 abortifacient in the package insert to avert off-label use. 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 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.

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).

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Ulipristal acetate

Start with the simplest possible case. Write down what Ulipristal acetate claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Ulipristal acetate before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Ulipristal acetate ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Ulipristal acetate

In research: Ulipristal acetate appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Ulipristal acetate in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Ulipristal acetate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Acetate esters, Antiglucocorticoids, Antiprogestogens, so understanding it makes those chapters shorter.
In everyday life: Look for Ulipristal acetate outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Ulipristal acetate in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Ulipristal acetate means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Ulipristal acetate out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Ulipristal acetate in simple terms?

Why does Ulipristal acetate matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Ulipristal acetate?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Ulipristal acetate.