chemistry

Quinine

Quinine 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 Quinine rather than just read about it. In short: Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to Plasmodium falciparum that is resistant to chloroquine when artesunate is not available.

Key takeaways

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

Reference excerpt

Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to Plasmodium falciparum that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg cramps, quinine is not recommended for this purpose due to the risk of serious side effects. It can be taken by mouth or intravenously. Malaria resistance to quinine occurs in certain areas of the world. Quinine is also used as an ingredient in tonic water and other beverages to impart a bitter taste. Common side effects include headache, ringing in the ears, vision issues, and sweating. More severe side effects include deafness, low blood platelets, and an irregular heartbeat. Use can make one more prone to sunburn. While it is unclear if use during pregnancy carries potential for fetal harm, treating malaria during pregnancy with quinine when appropriate is still recommended. Quinine is an alkaloid, a naturally occurring chemical compound. It possesses a C9H7N quinoline functional group (pyridine fused to benzene). Quinine was first isolated in 1820 from the bark of a cinchona tree, which is native to Peru, and its molecular formula was determined by Adolph Strecker in 1854. The class of chemical compounds to which it belongs is thus called the cinchona alkaloids. Bark extracts had been used to treat malaria since at least 1632 and it was introduced to Spain as early as 1636 by Jesuit missionaries returning from the New World. It is on the World Health Organization's List of Essential Medicines. Treatment of malaria with quinine marks the first known use of a chemical compound to treat an infectious disease.

Uses

Medical As of 2006, quinine is no longer recommended by the World Health Organization (WHO) as a first-line treatment for malaria, because there are other substances that are equally effective with fewer side effects. They recommend that it be used only when artemisinins are not available. Quinine is also used to treat lupus and arthritis. Quinine was frequently prescribed as an off-label treatment for leg cramps at night, but this has become less common since 2010 due to a warning from the US Food and Drug Administration (FDA) that such practice is associated with life-threatening side effects. Quinine can also act as a competitive inhibitor of monoamine oxidase (MAO), an enzyme that removes neurotransmitters from the brain. As an MAO inhibitor, it has potential to serve as a treatment for individuals with psychological disorders, similar to antidepressants that inhibit MAO.

Available forms Quinine is a basic amine and is usually provided as a salt. Various existing preparations include the hydrochloride, dihydrochloride, sulfate, bisulfate and gluconate. In the United States, quinine sulfate is commercially available in 324 mg tablets under the brand name Qualaquin. All quinine salts may be given orally or intravenously (IV); quinine gluconate may also be given intramuscularly (IM) or rectally (PR). The main problem with rectal administration is that the dose can be expelled before it is completely absorbed; in practice, this is corrected by giving a further half dose. No injectable preparation of quinine is licensed in the US; quinidine is used instead.

Beverages

Quinine is a flavor component of tonic water and bitter lemon soft drinks. On the soda gun behind many bars, tonic water is designated by the letter "Q" representing quinine. Tonic water was initially marketed as a means of delivering quinine to consumers in order to offer anti-malarial protection. According to tradition, because of the bitter taste of anti-malarial quinine tonic, British colonials in India mixed it with gin to make it more palatable, thus creating the gin and tonic cocktail, which is still popular today. While it is possible to drink enough tonic water to temporarily achieve quinine levels that offer anti-malarial protection, it is not a sustainable long-term means of protection. In France, quinine is an ingredient of an apéritif known as quinquina, or "Cap Corse", and the wine-based apéritif Dubonnet. In Spain, quinine (also known as "Peruvian bark" for its origin from the native cinchona tree) is sometimes blended into sweet Malaga wine, which is then called "Malaga Quina". In Italy, the traditional flavoured wine Barolo Chinato is infused with quinine and local herbs, and is served as a digestif. In Britain, the company A.G. Barr uses quinine as an ingredient in the carbonated and caffeinated beverage Irn-Bru. In Uruguay and Argentina, quinine is an ingredient of a PepsiCo tonic water named Paso de los Toros. In Denmark, it is used as an ingredient in the carbonated sports drink Faxe Kondi made by Royal Unibrew. As a flavouring agent in drinks, quinine is limited to 83 ppm (83 mg/L) in the United States, to 85 mg/L in Taiwan, and to 100 mg/L in the European Union. Direct use of cinchona bark in beverages is also allowed in the US, with a maximum allowed total cinchona alkaloid level of 83 ppm in the finished beverage.

Scientific Quinine (and quinidine) are used as the chiral moiety for the ligands used in Sharpless asymmetric dihydroxylation as well as for numerous other chiral catalyst backbones. Because of its relatively constant and well-known fluorescence quantum yield, quinine is used in photochemistry as a common fluorescence standard.

Contraindications Because of the narrow difference between its therapeutic and toxic effects, quinine is a common cause of drug-induced disorders, including thrombocytopenia and thrombotic microangiopathy. Even from minor levels occurring in common beverages, quinine can have severe adverse effects involving multiple organ systems, among which are immune system effects and fever, hypotension, hemolytic anemia, acute kidney injury, liver toxicity, and blindness. In people with atrial fibrillation, conduction defects, or heart block, quinine can cause heart arrhythmias, and should be avoided. Quinine can cause hemolysis in G6PD deficiency (an inherited deficiency), but this risk is small and the physician should not hesitate to use quinine in people with G6PD deficiency when there is no alternative. While not necessarily an absolute contraindication, concomitant administration of quinine with drugs primarily metabolized by CYP2D6 may lead to higher than expected plasma concentrations of the drug, due to quinine's strong inhibition of the enzyme.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Quinine

Start with the simplest possible case. Write down what Quinine 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 Quinine 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 Quinine 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 Quinine

In research: Quinine 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 Quinine 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: Quinine is common in secondary-school and first-year university syllabi. It links to neighbouring topics Antimalarial agents, Bitter compounds, CYP2D6 inhibitors, so understanding it makes those chapters shorter.
In everyday life: Look for Quinine 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.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Quinine in 20 minutes

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

Frequently asked questions

What is Quinine in simple terms?

Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to Plasmodium falciparum that is resistant to chloroquine when artesunate is not available.

Why does Quinine 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 Quinine?

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 Quinine.