chemistry

Tienilic acid

Tienilic acid 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 Tienilic acid rather than just read about it. In short: Tienilic acid (INN and BAN) or ticrynafen (USAN) is a loop diuretic drug with uric acid-lowering (uricosuric) action, formerly marketed for the treatment of hypertension. It was approved by FDA on May 2, 1979, and withdrawn in 1982, after case reports in the United States indicated a link between the use of ticrynafen and hepatitis.

Key takeaways

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

Reference excerpt

Tienilic acid (INN and BAN) or ticrynafen (USAN) is a loop diuretic drug with uric acid-lowering (uricosuric) action, formerly marketed for the treatment of hypertension. It was approved by FDA on May 2, 1979, and withdrawn in 1982, after case reports in the United States indicated a link between the use of ticrynafen and hepatitis. Criminal charges were brought against SmithKline executives with regard to hiding data related to toxicity while gaining FDA approval. The company pleaded guilty to 14 counts of failure to report adverse reactions and 20 counts of selling a misbranded drug. Tienilic acid was found to act as a suicide substrate at the cytochrome P450 enzymes involved in drug metabolism. However, the metabolic reaction carried out by these enzymes converted tienilic acid to a thiophene sulfoxide which was highly electrophilic. This encouraged a Michael reaction leading to alkylation of a thiol group in the enzyme's active site. Loss of water from the thiophene sulfoxide restored the thiophene ring and resulted in tienilic acid being covalently linked to the enzyme, thus inhibiting the enzyme irreversibly. In addition sera of patients who had liver failure after taking this drug contained antibodies recognizing CYP2C9 able to hydroxylate the drug and to give covalent binding. The above explanation is a hypothesis. It is still not known (after 15 years) if the reactive intermediate which inactivates the CYP2C9 is the thiophene sulfoxide or the thiophene epoxide. The target on the protein is also not known (could be multiple). However tienilic acid is a good mechanism based inhibitor of CYP2C9 and seems to inactivate it stoichiometrically. Progress in proteomics may one day give the answer. Recent studies indicate that in fact the primary metabolite of tienilic acid (5-OH tienilic acid) cannot be derived from a thiophene-S-oxide intermediate as was previously hypothesized. It was determined to be derived from a thiophene epoxide intermediate and this reactive intermediate is then likely a cause for the covalent binding to as well as mechanism-based inactivation of CYP2C9.

References

Illustrations

Worked examples

Example 1 — a first encounter with Tienilic acid

Start with the simplest possible case. Write down what Tienilic acid 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 Tienilic acid 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 Tienilic acid 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 Tienilic acid

In research: Tienilic acid 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 Tienilic acid 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: Tienilic acid is common in secondary-school and first-year university syllabi. It links to neighbouring topics Acetic acids, Chlorobenzene derivatives, Diuretics, so understanding it makes those chapters shorter.
In everyday life: Look for Tienilic acid 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 Tienilic acid in 20 minutes

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

Frequently asked questions

What is Tienilic acid in simple terms?

Why does Tienilic acid 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 Tienilic acid?

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 Tienilic acid.