Quinine Hydrochloride Dihydrate CAS 6119-47-7

Its molecular structure contains a quinoline ring and a methoxyquinoline ring, and this unique bicyclic structure endows it with multiple pharmacological activities. Quinine hydrochloride has been used to treat malaria for nearly 400 years, from its discovery in the 17th century to its successful isolation into pure form in the 19th century, and still plays a role in the global anti malaria front line today. It is not only the first widely used antimalarial drug in human history, but also one of the starting points of modern medicinal chemistry - it is the study of quinine structure that gave birth to a series of synthetic antimalarial drugs such as chloroquine and mefloquine.

The most essential and irreplaceable use is to treat malaria. This is also its most primitive and important mission since its discovery from the bark of cinchona bark.
Its anti malaria mechanism is very clear: quinine can quickly penetrate the cell membrane of malignant malaria parasites, causing an increase in calcium ion concentration in the parasite, resulting in the destruction of the nuclear membrane, thereby inhibiting the growth and reproduction of parasites and killing malaria parasites in red blood cells. Meanwhile, quinine can also inhibit the uptake of glucose by malaria parasites, making them unable to survive due to energy depletion.

In clinical practice, quinine hydrochloride dihydrate is mainly used for the following types of malaria: cerebral malaria and other severe malignant malaria, which are the most critical application scenarios. It is usually administered intravenously with quinine hydrochloride injection, at a dose of 5 to 10 milligrams per kilogram of body weight (maximum amount of 0.5 grams), after 4 hours, and can be repeated 12 hours later. After the condition improves, it can be switched to oral administration. In addition, it is also used to treat intermittent malaria and chloroquine resistant malignant malaria, and is an important alternative for patients with chloroquine resistant malaria.

In compound preparations, it is often used in combination with artemisinin, sulfamethoxazole, pyrimethamine, and other drugs. For example, artemisinin quinine tablets combine the quick acting malaria killing effect of artemisinin with the long-lasting inhibition effect of quinine, which can quickly control symptoms and prevent recurrence. It is one of the recommended antimalarial combination therapy regimens by the World Health Organization. Compound quinine injection plays a synergistic role in antipyretic, antimalarial, anti-inflammatory, antiemetic, and anticonvulsant effects.

It should be emphasized that it is contraindicated for pregnant women because it has an inducing effect and can cause fetal hearing loss and congenital damage to the central nervous system and limbs through the placenta. Patients with glucose-6-phosphate dehydrogenase deficiency are also contraindicated, as quinine can induce acute hemolytic anemia, leading to black urine fever and acute renal failure.

Quinine hydrochloride has a clear antipyretic effect, which is achieved by inhibiting the hypothalamic thermoregulatory center, increasing heat dissipation and reducing heat production, thereby reducing fever symptoms. In the era before antibiotics and acetaminophen were available, quinine was one of the most important antipyretic drugs in Europe, widely used to treat high fever caused by various reasons.

In addition to antipyretic effects, it also has anti-inflammatory and analgesic effects. Its anti-inflammatory mechanism mainly involves inhibiting the cyclooxygenase pathway in arachidonic acid metabolism, blocking prostaglandin synthesis, and thereby reducing inflammatory reactions.

At the same time, quinine has strong antibacterial activity against various Gram positive bacteria, so it has also been used in anti rheumatic therapy in history to alleviate arthritis symptoms by inhibiting the production of inflammatory factors such as interleukin-1 β.
However, due to its relatively large side effects, its antipyretic and analgesic uses have gradually been replaced by safer drugs in modern clinical practice. However, in specific scenarios such as high fever caused by malaria and certain refractory fever, it is still an irreplaceable choice.

This is an easily overlooked but clinically significant use. Quinine has a direct effect on myocardial cells, which can depolarize membrane potential, slow down conduction velocity, prolong myocardial refractory period, and thus have a significant anti arrhythmic effect.
In clinical practice, it is occasionally used to treat certain refractory arrhythmias, especially atrial fibrillation.

Its mechanism of action is related to quinine's ability to enhance the frequency of chloride ion channel opening mediated by gamma aminobutyric acid type A receptors, achieving stable electrophysiological activity through central nervous system inhibition. But this use must be carried out under strict monitoring of electrocardiogram conditions, as quinine has significant cardiac toxicity, high doses can damage nerve tissue and constrict retinal blood vessels, intravenous injection is rare for atrioventricular block, ventricular fibrillation, and even sudden death. Therefore, intravenous infusion is strictly prohibited and can only be administered slowly. Patients with asthma, atrial fibrillation, and other serious heart diseases should use it with caution.

Has anticonvulsant effects and can relieve muscle rigidity caused by excessive nerve impulses. Its mechanism is to block neuromuscular conduction and inhibit cortical neurons, which helps stabilize electrophysiological activity and prevent epileptic seizures. Clinically, it is commonly used to treat convulsive states caused by various reasons such as electrolyte imbalance or hypoxia, and is generally administered intravenously or intramuscularly. In terms of antiemetic effects, it can inhibit the vomiting center and have an antiemetic effect.

For nausea and vomiting caused by motion sickness, seasickness, etc., it can be used under the guidance of a doctor. However, quinine hydrochloride dihydrate is worth noting that quinine can also stimulate the vomiting center to produce emetic effects. This bidirectional effect depends on the dosage and administration method, with low-dose inhibition and high-dose excitation, which is also one of the reasons why its use requires precise dosage control.

In addition, it can reduce the excitability of motor nerve endings and the involuntary contraction of muscle fibers, so it is also used to treat nocturnal leg cramps. Quinine sulfate tablets are a commonly used oral dosage form.

Has the ability to kill amoebic protozoa and is effective against amoebic diseases. Due to its ability to compete with alkaloid toxins for excretion and its mild diuretic effect, quinine has been historically used as an antidote to promote the elimination of toxins from the body.
However, these two uses are less commonly used in modern clinical practice, and there are more specialized drugs such as metronidazole for anti amoebic diseases, as well as more efficient detoxification plans. But understanding these uses helps to comprehend their pharmacological breadth as' broad-spectrum alkaloids'.

This is a very special and still in use use use of quinine hydrochloride. According to the records of applied pharmacology in dermatology, quinine salts have the ability to defend against ultraviolet radiation, absorb ultraviolet radiation, and protect the skin from light damage.
In clinical dermatology, it is made into a 2% to 5% solution, powder or ointment for the treatment of photodermatitis, including photodermatitis, lupus erythematosus, vegetable dermatitis, etc.

Its formulation forms include topical solutions, powders, and ointments, which are directly applied to the affected area and exert light shielding protection through a dual mechanism of local absorption and surface shielding.
Although the volume of this use is not large, it is irreplaceable in specific patient populations, especially for patients who are allergic to ultraviolet radiation. Quinine preparations are one of the few clinically proven effective topical light avoidance drugs.

There is a unique and ongoing use in the food industry - as a bittering agent in beverage production. The most classic product is "Tonic Water", also known as Tonic Water.
Quinine has an extremely strong and distinct bitterness, which cannot be completely masked by other sweeteners, and is therefore widely used in bitter drinks such as tonic water and bitterer lemon.

In history, British colonizers drank quinine water in tropical regions to prevent malaria. Although the actual preventive effect was limited, this habit has continued to this day, making quinine water an indispensable base drink in global cocktail culture. Gin&Tonic is the most typical representative.
In the regulations on food additives, quinine is allowed to be used as a bitter taste agent, but the dosage must be strictly controlled, as excessive intake can also cause cinchona reactions such as tinnitus, headache, dizziness, nausea, vomiting, etc.

In the field of scientific research, it is used as a potassium ion channel inhibitor to suppress the mSlo3 (KCa5.1) channel current caused by voltage pulses, and is an important tool drug in electrophysiological research.
In analytical chemistry, quinine can also be used to interfere with the determination of 17 hydroxysteroids. Although this property is considered an "interfering factor" in clinical diagnosis, it can also be reverse utilized in the development of specific analytical methods. In addition, deuterated derivatives of quinine are used as labeled compounds and internal standards in nuclear magnetic resonance studies, with specific applications in high-end drug metabolism research.