antimalarial, skeletal muscle relaxant
Primary alkaloid of various species of Cinchona (Rubiaceae). Optical isomer of Quinidine. Antimalarial; muscle relaxant (skeletal)
white to light yellow crystal powde
Quinine is one of the oldest antimalarial drugs. At as early as the 15th century, the quinine-containing cinchona bark has been used extensively in the treatment of malaria with its antimalarial effect being similar to that of chloroquine that is through interfering with DNA synthesis effect. It is capable of inhibiting the erythrocytic stage of a variety of Plasmodium, being able to control the malaria symptoms. It also has certain killing effect on the gametes of vivax malaria and quartan malaria. However, it has no effect on the exoerythrocytic stage. Its major advantage is not easy to produce drug resistance, possibly due to that quinine binds the plasmodium DNA in a different way from chloroquine, so having no cross-resistance and can be used for the treatment of the infection of anti-chloroquine strains (especially Plasmodium falciparum). In addition, quinine can also exciting the uterus, inhibit the myocardium and have antipyretic analgesic effect. In addition to medicinal application, in analytical chemistry it can be used as the detection agent of bismuth, platinum and other metal ions and also be used for the separation agent of racemic organic acid.
Because of its relatively constant and well-known fluorescence quantum yield, quinine is also used in photochemistry as a common fluorescence standard. It has been used for imaging of oxygen evolution and oxide formation. Chloride and bromide have been sh
Quinine, an alkaloid derived from the bark of the cinchona tree, is a blood schizontocidal agent that is more toxic than chloroquine.Quinine is used to treat malaria caused by Plasmodium falciparum. Plasmodium falciparum is a parasite that gets into the red blood cells in the body and causes malaria. Quinine works by killing the parasite or preventing it from growing. This medicine may be used alone or given together with one or more medicines for malaria.
Quinine should not be used to treat or prevent night time leg cramps. This medicine may cause very serious unwanted effects and should only be used for patients with malaria.It is administered parenterally to patients with severe or complicated malaria who cannot take drugs by mouth because of coma, convulsions or vomiting.
It is administered orally to less seriously ill patients with infections likely to be resistant to chloroquine or mefloquine, sometimes in combination with pyrimethamine/sulfadoxine or a tetracycline.
Quinine is an extremely basic compound and is, therefore, always presented as a salt. Various preparations exist, including the hydrochloride, dihydrochloride, sulphate, bisulphate, and gluconate salts; of these the dihydrochloride is the most widely used. Quinine has rapid schizonticidal action against intra-erythrocytic malaria parasites. It is also gametocytocidal for Plasmodium vivax and Plasmodium malariae, but not for Plasmodium falciparum. Quinine also has analgesic, but not antipyretic properties. The anti-malarial mechanism of action of quinine is unknown.
Crystallise the quinine from absolute EtOH. It has been used as a chiral catalyst (see previous entry). [Beilstein 23 H 511, 23 I 166, 23 II 416, 23 III/IV 3265, 23/13 V 395.]
1. It is not suitable to be used in combination with aminoglycoside antibiotics, furosemide and etacrynic acid
2. It is often used in combination with primaquine or pyrimethamine in order to achieve curing and enhance the effectiveness of the control of resistant strains.
The most frequently encountered signs of Quinine overdosage are:
- Tinnitus, decreased auditory acuity and vertigo. Permanent deafness has resulted from exposure to toxic doses.
- Amblyopia, constricted visual fields, diplopia and night blindness. Recovery is slow but usually complete.
- Quinidine-like effects resulting in hypotension, conduction disturbances, anginal symptoms and ventricular tachycardia.
- A local irritant effect on the gastrointestinal tract resulting in nausea, vomiting, abdominal pain and diarrhoea.
A single oral dose greater than 3 g is capable of causing serious and potentially fatal intoxication in adults, preceded by depression of the central nervous system and seizures. Much smaller doses can be lethal in children.
Dysrhythmias, hypotension and cardiac arrest can result from the cardiotoxic action and ocular toxicity can lead to blindness.
Emesis should be induced and gastric lavage undertaken as rapidly as possible. Activated charcoal should then be administered.
Supportive measures, to be employed as necessary, include ventilation, and symptomatic treatment of dysrhythmias, cardiac failure and convulsions. No specific measures of proven efficacy exist to reduce the toxicity or to promote the excretion of quinine.
1. Large doses can easily lead to the damage of the eighth cranial nerve and optic nerve. Patients of deafness, vestibular disorders and optic neuritis should be disabled. Patients suffering from acute phlebitis, nephritis, diabetes, cardiovascular disease, bradycardia, atrioventricular blocking should be disabled. Large doses have the effect of teratogenic and exciting the uterine smooth muscle. Menstrual women and pregnant women should be disabled for using it. It can reduce the skeletal muscle excitability so patients of myasthenia gravis should be disabled.
2 It has effects of inhibiting the heart with Intravenous infusion being easily lead to shock and not suitable for usage. Upon intravenous infusion, the patients should subject to close observation in changes of blood pressure; intramuscular injection can cause tissue necrosis, so it should be adopted of the deep gluteal muscle injection. It is forbidden to use in combination with quinidine and chloroquine so as not to cause cardiac arrest.
ChEBI: A cinchona alkaloid that is cinchonidine in which the hydrogen at the 6-position of the quinoline ring is substituted by methoxy.
1, cinchona reaction: this can occur when the daily quinine dosage exceeds more than 1g or a little longer, manifested as nausea, vomiting, tinnitus, headache, vision hearing loss, generally being able to be restored after drug withdrawal
2, specific reaction: it can be observed of acute hemolysis, dermatitis, itching, angioneurotic edema and bronchial asthma. A small number of patients with falciparum malaria, after administrating quinine, can get chills, fever, vomiting, hemoglobinuria, urinary retention and other acute hemolytic disease, called black urine heat which can be fatal in severe cases.
3, intravenous injection, can inhibit the heart and further cause decreased blood pressure and life-threatening shock, thus it is strictly prohibited to adopt intravenous injection. Intravenous infusion should be administrated with caution. Intramuscular injection is prone to cause tissue necrosis, and thus is generally not used except in cases that oral administration is not doable.
It can be subject to rapid and complete oral absorption with its plasma concentration being able to reach peak within 1 to 3 hours. It also has a plasma protein binding rate of about 70%. The concentration in the cerebrospinal fluid is about 2% to 5% of that in the plasma. It has a half-life of 7 to 8 hours. It can quickly penetrate through the placenta while the absorption through subcutaneous and intramuscular injection is slow. It is mainly subject to liver metabolism with about 5% of the dosage amount being excreted from the urine in the original form.
Clinically, quinine is mainly applied to the chloroquine-resistant patients infected with Plasmodium. Also used for the treatment of vivax malaria and falciparum malaria. Those for medical usage are all quinine salts. Sulfate can be used for oral administration while its hydrochloride is for injection. Until the 1920s, it had been an excellent anti-malaria drug. However, if used improperly, it can also cause poisoning, headaches, tinnitus, diarrhea, rash, vision and hearing disorders. It only has inhibitory effect on protozoan parasites without killing effect. The patient can still get relapse after being cured. To this end, scientists are still seeking more effective antimalarial drugs. Drugs currently in application include atabrine, plasmochin, chloroquinoline and so on. From a Chinese plant, antipyretic dichroa, people can extract a feerifuqine with its antimalarial effect being 100 times higher than quinine. However, it can’t be directly administrated due to the large toxicity. People are studying the structure and pharmacological effects of feerifuqine in order to find out the higher-efficacy antimalarial drugs.