science

Trilostane

Trilostane is a science 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 Trilostane rather than just read about it. In short: Trilostane, sold under the brand name Vetoryl among others, is a medication which has been used in the treatment of Cushing's syndrome, Conn's syndrome, and postmenopausal breast cancer in humans. It was withdrawn for use in humans in the United States in the 1990s but was subsequently approved for use in veterinary medicine in the 2000s to treat Cushing's syndrome in dogs.

Key takeaways

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

Reference excerpt

Trilostane, sold under the brand name Vetoryl among others, is a medication which has been used in the treatment of Cushing's syndrome, Conn's syndrome, and postmenopausal breast cancer in humans. It was withdrawn for use in humans in the United States in the 1990s but was subsequently approved for use in veterinary medicine in the 2000s to treat Cushing's syndrome in dogs. It is taken by mouth.

Medical uses Trilostane has been used in the treatment of Cushing's syndrome (hypercortisolism), Conn's syndrome (hyperaldosteronism), and postmenopausal breast cancer in humans. When used to treat breast cancer, trilostane is administered in combination with a corticosteroid to prevent glucocorticoid deficiency.

Contraindications Trilostane should not be used in pregnant women. Trilostane should not be given to a dog that:

Has kidney or liver disease Takes certain medications used to treat cardiovascular disease Is pregnant, nursing or intended for breeding

Side effects Side effects of trilostane in conjunction with a corticosteroid in humans include gastrointestinal side effects like gastritis, nausea, vomiting, and diarrhea. Nonsteroidal antiinflammatory drugs (NSAIDs) may decrease the incidence of diarrhea with trilostane. Serious gastrointestinal side effects of trilostane alone or in combination with an NSAID like peptic ulcer, erosive gastritis, gastric perforation, hematemesis, and melena may occur in some individuals. Reversible granulocytopenia and transient oral paresthesia may occur with trilostane.

Pharmacology

Pharmacodynamics

Trilostane is a steroidogenesis inhibitor. It is specifically an inhibitor of 3β-hydroxysteroid dehydrogenase (3β-HSD). As a result of this action, trilostane blocks the conversion of Δ5-3β-hydroxysteroids, including pregnenolone, 17α-hydroxypregnenolone, dehydroepiandrosterone (DHEA), and androstenediol, into Δ4-3-ketosteroids, including progesterone, 17α-hydroxyprogesterone, androstenedione, and testosterone, respectively. Consequently, trilostane inhibits the production of all classes of steroid hormones, including androgens, estrogens, progestogens, glucocorticoids, and mineralocorticoids. The mechanism of action of trilostane in Cushing's syndrome and Conn's syndrome is by inhibiting the production of corticosteroids such as cortisol and aldosterone in the adrenal glands. Trilostane has also been used as an abortifacient due to its inhibition of progesterone synthesis. Trilostane is not an aromatase inhibitor and hence does not inhibit the conversion of androgens like androstenedione and testosterone into estrogens like estrone and estradiol. However, trilostane may nonetheless inhibit estrogen synthesis by inhibiting androgen synthesis. In addition to steroidogenesis inhibition, trilostane has been found to act as a noncompetitive antiestrogen, via direct and presumably allosteric interactions with the estrogen receptor. The effectiveness of trilostane in postmenopausal breast cancer may relate to this apparent antiestrogenic activity. Trilostane has also been found to act as an agonist of the androgen receptor. As such, its use in men with prostate cancer may warrant caution.

Pharmacokinetics Trilostane is metabolized in the liver. The major metabolite of trilostane is 17-ketotrilostane. The conversion of trilostane into 17-ketotrilostane is reversible, suggesting that trilostane and 17-ketotrilostane undergo interconversion in the body. 17-Ketotrilostane circulates at 3-fold higher levels than trilostane and is more active than trilostane as a 3β-HSD inhibitor. The elimination half-lives of trilostane and 17-ketotrilostane are both 1.2 hours, with both compounds cleared from the blood within 6 to 8 hours of a dose of trilostane. 17-Ketotrilostane is excreted by the kidneys.

Chemistry Trilostane, also known as 4α,5-epoxy-3,17β-dihydroxy-5α-androst-2-ene-2-carbonitrile, is a synthetic androstane steroid and a derivative of 5α-reduced androstane derivatives like 3α-androstanediol, 3β-androstanediol, and dihydrotestosterone.

Synthesis Trilostane is prepared from testosterone in a four-step synthesis.

History Trilostane was withdrawn from human use in the United States market in April 1994. It continued to be available in the United Kingdom for use in humans under the brand name Modrenal for the treatment of Cushing's disease and breast cancer in humans, but was eventually discontinued in this country as well. Trilostane was approved in the United States in 2008 for the treatment of Cushing's disease (hyperadrenocorticism) in dogs under the brand name Vetoryl. It was available by prescription in the United Kingdom for dogs under the Vetoryl brand name for some time before it was approved in the United States. The drug is also used to treat the skin disorder Alopecia X in dogs. Trilostane was the first drug approved to treat both pituitary- and adrenal-dependent Cushing's in dogs. Only one other drug, Anipryl (veterinary brand name) selegiline, is FDA-approved to treat Cushing's disease in dogs, but only to treat uncomplicated, pituitary-dependent Cushing's. The only previous treatment for the disease was the use of mitotane (brand name Lysodren) off-label. A number of compounding pharmacies in the United States sell trilostane for dogs. Since the United States approval of Vetoryl in December 2008, compounding pharmacies are no longer able to use a bulk drug product for compounding purposes, but must prepare the compounded drug from Vetoryl.

Society and culture

Legal status In March 2024, the Committee for Veterinary Medicinal Products (CVMP) of the European Medicines Agency adopted a positive opinion, recommending the granting of a marketing authorization for the veterinary medicinal product Trilocur, oral suspension for dogs. The applicant for this veterinary medicinal product is Emdoka. In March 2024, the CVMP adopted a positive opinion, recommending the granting of a marketing authorization for the veterinary medicinal product Trilorale, oral suspension for dogs. The applicant for this veterinary medicinal product is Axience. Trilocur and Trilorale were approved for medical use in the European Union in May 2024.

Generic names Trilostane is the generic name of the drug and its INNTooltip International Nonproprietary Name, USANTooltip United States Adopted Name, BANTooltip British Approved Name, and JANTooltip Japanese Accepted Name. Its developmental code name was WIN-24,540.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Trilostane

Start with the simplest possible case. Write down what Trilostane claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Trilostane 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 Trilostane 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 Trilostane

In research: Trilostane appears in science 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 Trilostane 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: Trilostane is common in secondary-school and first-year university syllabi. It links to neighbouring topics 11β-Hydroxylase inhibitors, 3β-Hydroxysteroid dehydrogenase inhibitors, Androgens, so understanding it makes those chapters shorter.
In everyday life: Look for Trilostane 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 Trilostane in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Trilostane 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 Trilostane out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Trilostane in simple terms?

Why does Trilostane matter?

Because it connects several science 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 Trilostane?

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 Trilostane.