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Pronunciation | /ˈklɔːrəkwiːn/ |
Trade names | Aralen, other |
Other names | Chloroquine phosphate |
AHFS/Drugs.com | Monograph |
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Routes of administration | By mouth |
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Pharmacokinetic data | |
Metabolism | Liver |
Elimination half-life | 1-2 months |
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ECHA InfoCard | 100.000.175 |
Chemical and physical data | |
Formula | C18H26ClN3 |
Molar mass | 319.88 g·mol−1 |
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Chloroquine is an antiparasitic medication that treats malaria. It works by increasing the levels of haeme in the blood, a substance toxic to the malarial parasite. This kills the parasite and stops the infection from spreading. [1] Certain types of malaria, resistant strains, and complicated cases typically require different or additional medication. [1] Chloroquine is also occasionally used for amebiasis that is occurring outside the intestines, rheumatoid arthritis, and lupus erythematosus. [1] While it has not been formally studied in pregnancy, it appears safe. [1] [2] It was studied to treat COVID-19 early in the pandemic, but these studies were largely halted in the summer of 2020, and the NIH does not recommend its use for this purpose. [3] It is taken by mouth. [1]
Common side effects include muscle problems, loss of appetite, diarrhea, and skin rash. [1] Serious side effects include problems with vision, muscle damage, seizures, and low blood cell levels. [1] [4] Chloroquine is a member of the drug class 4-aminoquinoline. [1] As an antimalarial, it works against the asexual form of the malaria parasite in the stage of its life cycle within the red blood cell. [1] How it works in rheumatoid arthritis and lupus erythematosus is unclear. [1]
Chloroquine was discovered in 1934 by Hans Andersag. [5] [6] It is on the World Health Organization's List of Essential Medicines. [7] It is available as a generic medication. [1]
Chloroquine has been used in the treatment and prevention of malaria from Plasmodium vivax , P. ovale , and P. malariae . It is generally not used for Plasmodium falciparum as there is widespread resistance to it. [9] [10]
Chloroquine has been extensively used in mass drug administrations, which may have contributed to the emergence and spread of resistance. It is recommended to check if chloroquine is still effective in the region prior to using it. [11] In areas where resistance is present, other antimalarials, such as mefloquine or atovaquone, may be used instead. The Centers for Disease Control and Prevention recommend against treatment of malaria with chloroquine alone due to more effective combinations. [12]
In treatment of amoebic liver abscess, chloroquine may be used instead of or in addition to other medications in the event of failure of improvement with metronidazole or another nitroimidazole within five days or intolerance to metronidazole or a nitroimidazole. [13]
As it mildly suppresses the immune system, chloroquine is used in some autoimmune disorders, such as rheumatoid arthritis and has an off-label indication for lupus erythematosus. [1]
Side effects include blurred vision, nausea, vomiting, abdominal cramps, headache, diarrhea, swelling legs/ankles, shortness of breath, pale lips/nails/skin, muscle weakness, easy bruising/bleeding, hearing and mental problems. [14] [15]
Chloroquine has not been shown to have any harmful effects on the fetus when used in the recommended doses for malarial prophylaxis. [22] Small amounts of chloroquine are excreted in the breast milk of lactating women. However, this drug can be safely prescribed to infants, the effects are not harmful. Studies with mice show that radioactively tagged chloroquine passed through the placenta rapidly and accumulated in the fetal eyes which remained present five months after the drug was cleared from the rest of the body. [16] [23] Women who are pregnant or planning on getting pregnant are still advised against traveling to malaria-risk regions. [22]
There is not enough evidence to determine whether chloroquine is safe to be given to people aged 65 and older. Since it is cleared by the kidneys, toxicity should be monitored carefully in people with poor kidney functions, as is more likely to be the case in the elderly. [16]
Chloroquine has a number of drug–drug interactions that might be of clinical concern:[ citation needed ]
Chloroquine, in overdose, has a risk of death of about 20%. [24] It is rapidly absorbed from the gut with an onset of symptoms generally within an hour. [25] Symptoms of overdose may include sleepiness, vision changes, seizures, stopping of breathing, and heart problems such as ventricular fibrillation and low blood pressure. [24] [25] Low blood potassium may also occur. [24]
While the usual dose of chloroquine used in treatment is 10 mg/kg, toxicity begins to occur at 20 mg/kg, and death may occur at 30 mg/kg. [24] In children as little as a single tablet can be fatal. [25] [16]
Treatment recommendations include early mechanical ventilation, cardiac monitoring, and activated charcoal. [24] Intravenous fluids and vasopressors may be required with epinephrine being the vasopressor of choice. [24] Seizures may be treated with benzodiazepines. [24] Intravenous potassium chloride may be required, however this may result in high blood potassium later in the course of the disease. [24] Dialysis has not been found to be useful. [24]
This section needs additional citations for verification .(March 2024) |
Absorption of chloroquine is rapid and primarily happens in the gastrointestinal tract. [26] It is widely distributed in body tissues. [27] Protein binding in plasma ranges from 46% to 79%. [28] Its metabolism is partially hepatic, giving rise to its main metabolite, desethylchloroquine. [29] Its excretion is ≥50% as unchanged drug in urine, where acidification of urine increases its elimination.[ citation needed ] It has a very high volume of distribution, as it diffuses into the body's adipose tissue.[ citation needed ]
Accumulation of the drug may result in deposits that can lead to blurred vision and blindness. [30] It and related quinines have been associated with cases of retinal toxicity, particularly when provided at higher doses for longer times.[ citation needed ] With long-term doses, routine visits to an ophthalmologist are recommended.[ citation needed ]
Chloroquine is also a lysosomotropic agent, meaning it accumulates preferentially in the lysosomes of cells in the body.[ citation needed ] The pKa for the quinoline nitrogen of chloroquine is 8.5, meaning it is about 10% deprotonated at physiological pH (per the Henderson-Hasselbalch equation).[ citation needed ] This decreases to about 0.2% at a lysosomal pH of 4.6.[ citation needed ] Because the deprotonated form is more membrane-permeable than the protonated form, a quantitative "trapping" of the compound in lysosomes results.[ citation needed ]
The lysosomotropic character of chloroquine is believed to account for much of its antimalarial activity; the drug concentrates in the acidic food vacuole of the parasite and interferes with essential processes. Its lysosomotropic properties further allow for its use for in vitro experiments pertaining to intracellular lipid related diseases, [31] [32] autophagy, and apoptosis. [33]
Inside red blood cells, the malarial parasite, which is then in its asexual lifecycle stage, must degrade hemoglobin to acquire essential amino acids, which the parasite requires to construct its own protein and for energy metabolism. Digestion is carried out in a vacuole of the parasitic cell.[ citation needed ]
Hemoglobin is composed of a protein unit (digested by the parasite) and a heme unit (not used by the parasite). During this process, the parasite releases the toxic and soluble molecule heme. The heme moiety consists of a porphyrin ring called Fe(II)-protoporphyrin IX (FP). To avoid destruction by this molecule, the parasite biocrystallizes heme to form hemozoin, a nontoxic molecule. Hemozoin collects in the digestive vacuole as insoluble crystals.[ citation needed ]
Chloroquine enters the red blood cell by simple diffusion, inhibiting the parasite cell and digestive vacuole. Chloroquine (CQ) then becomes protonated (to CQ2+), as the digestive vacuole is known to be acidic (pH 4.7); chloroquine then cannot leave by diffusion. Chloroquine caps hemozoin molecules to prevent further biocrystallization of heme, thus leading to heme buildup. Chloroquine binds to heme (or FP) to form the FP-chloroquine complex; this complex is highly toxic to the cell and disrupts membrane function. Action of the toxic FP-chloroquine and FP results in cell lysis and ultimately parasite cell autodigestion. [34] Parasites that do not form hemozoin are therefore resistant to chloroquine. [35]
Since the first documentation of P. falciparum chloroquine resistance in the 1950s, resistant strains have appeared throughout East and West Africa, Southeast Asia, and South America. The effectiveness of chloroquine against P. falciparum has declined as resistant strains of the parasite evolved.
Resistant parasites are able to rapidly remove chloroquine from the digestive vacuole using a transmembrane pump. Chloroquine-resistant parasites pump chloroquine out at 40 times the rate of chloroquine-sensitive parasites; the pump is coded by the P. falciparum chloroquine resistance transporter (PfCRT) gene. [36] The natural function of the chloroquine pump is to transport peptides: mutations to the pump that allow it to pump chloroquine out impairs its function as a peptide pump and comes at a cost to the parasite, making it less fit. [37]
Resistant parasites also frequently have mutation in the ABC transporter P. falciparum multidrug resistance (PfMDR1) gene, although these mutations are thought to be of secondary importance compared to PfCRT. An altered chloroquine-transporter protein, CG2 has been associated with chloroquine resistance, but other mechanisms of resistance also appear to be involved. [38]
Verapamil, a Ca2+ channel blocker, has been found to restore both the chloroquine concentration ability and sensitivity to this drug. Other agents which have been shown to reverse chloroquine resistance in malaria are chlorpheniramine, gefitinib, imatinib, tariquidar and zosuquidar. [39]
As of 2014 [update] chloroquine is still effective against poultry malaria in Thailand. Sohsuebngarm et al. 2014 test P. gallinaceum at Chulalongkorn University and find the parasite is not resistant. [40] : 1237 Sertraline, fluoxetine and paroxetine reverse chloroquine resistance, making resistant biotypes susceptible if used in a cotreatment. [41]
Chloroquine has antiviral effects against some viruses. [42] It increases late endosomal and lysosomal pH, resulting in impaired release of the virus from the endosome or lysosome — release of the virus requires a low pH. The virus is therefore unable to release its genetic material into the cell and replicate. [43] [44]
Chloroquine also seems to act as a zinc ionophore that allows extracellular zinc to enter the cell and inhibit viral RNA-dependent RNA polymerase. [45] [46]
Chloroquine inhibits thiamine uptake. [47] It acts specifically on the transporter SLC19A3.
Against rheumatoid arthritis, it operates by inhibiting lymphocyte proliferation, phospholipase A2, antigen presentation in dendritic cells, release of enzymes from lysosomes, release of reactive oxygen species from macrophages, and production of IL-1.[ medical citation needed ]
In Peru, the indigenous people extracted the bark of the Cinchona tree ( Cinchona officinalis ) [48] and used the extract to fight chills and fever in the seventeenth century. In 1633, this herbal medicine was introduced in Europe, where it was given the same use and also began to be used against malaria. The quinoline antimalarial drug quinine was isolated from the extract in 1820. [49] : 130–131
After World War I, the German government sought alternatives to quinine. Chloroquine, a synthetic analogue with the same mechanism of action was discovered in 1934, by Hans Andersag and coworkers at the Bayer laboratories, who named it resochin. [50] [51] It was ignored for a decade, because it was considered too toxic for human use. Instead, in World War II, the German Africa Corps used the chloroquine analogue 3-methyl-chloroquine, known as sontochin. After Allied forces arrived in Tunis, sontochin fell into the hands of Americans, who sent the material back to the United States for analysis, leading to renewed interest in chloroquine. [52] [53] United States government-sponsored clinical trials for antimalarial drug development showed unequivocally that chloroquine has a significant therapeutic value as an antimalarial drug. [49] : 61–66 It was introduced into clinical practice in 1947 for the prophylactic treatment of malaria. [54]
The first synthesis of chloroquine was disclosed in a patent filed by IG Farben in 1937. [55] In the final step, 4,7-dichloroquinoline was reacted with 1-diethylamino-4-aminopentane.
By 1949, chloroquine manufacturing processes had been established to allow its widespread use. [56]
Chloroquine comes in tablet form as the phosphate, sulfate, and hydrochloride salts. Chloroquine is usually dispensed as the phosphate. [57]
Brand names include Chloroquine FNA, Resochin, Dawaquin, and Lariago. [58]
Chloroquine, in various chemical forms, is used to treat and control surface growth of anemones and algae, and many protozoan infections in aquariums, [59] e.g. the fish parasite Amyloodinium ocellatum . [60] It is also used in poultry malaria. [40] : 1237
Chloroquine was proposed as a treatment for SARS, with in vitro tests inhibiting the severe acute respiratory syndrome coronavirus (SARS-CoV). [61] [62] In October 2004, a published report stated that chloroquine acts as an effective inhibitor of the replication of SARS-CoV in vitro. [61] In August 2005, a peer-reviewed study confirmed and expanded upon the results. [63]
Chloroquine was being considered in 2003, in pre-clinical models as a potential agent against chikungunya fever. [64]
This article needs to be updated.(April 2024) |
Chloroquine and hydroxychloroquine are anti-malarial medications also used against some auto-immune diseases. [65] Chloroquine, along with hydroxychloroquine, was an early experimental treatment for COVID-19. [66] Neither drug has been useful to prevent or treat SARS-CoV-2 infection. [67] [68] [69] [70] [71] [72] Administration of chloroquine or hydroxychloroquine to COVID-19 patients, either as monotherapies or in conjunction with azithromycin, has been associated with deleterious outcomes, such as QT prolongation. [73] [74] As of 2024, [update] scientific evidence does not substantiate the efficacy of hydroxychloroquine, with or without the addition of azithromycin, in the therapeutic management of COVID-19. [73]
Cleavage of the SARS-CoV-2 S2 spike protein required for viral entry into cells can be accomplished by proteases TMPRSS2 located on the cell membrane, or by cathepsins (primarily cathepsin L) in endolysosomes. [75] Hydroxychloroquine inhibits the action of cathepsin L in endolysosomes, but because cathepsin L cleavage is minor compared to TMPRSS2 cleavage, hydroxychloroquine does little to inhibit SARS-CoV-2 infection. [75]
Several countries initially used chloroquine or hydroxychloroquine for treatment of persons hospitalized with COVID-19 (as of March 2020), though the drug was not formally approved through clinical trials. [76] [77] From April to June 2020, there was an emergency use authorization for their use in the United States, [78] and was used off label for potential treatment of the disease. [79] On 24 April 2020, citing the risk of "serious heart rhythm problems", the FDA posted a caution against using the drug for COVID-19 "outside of the hospital setting or a clinical trial". [80]
Their use was withdrawn as a possible treatment for COVID-19 infection when it proved to have no benefit for hospitalized patients with severe COVID-19 illness in the international Solidarity trial and UK RECOVERY Trial. [81] [82] On 15 June 2020, the FDA revoked its emergency use authorization, stating that it was "no longer reasonable to believe" that the drug was effective against COVID-19 or that its benefits outweighed "known and potential risks". [83] [84] [85] In fall of 2020, the National Institutes of Health issued treatment guidelines recommending against the use of hydroxychloroquine for COVID-19 except as part of a clinical trial. [65]
In 2021, hydroxychloroquine was part of the recommended treatment for mild cases in India. [86]
In 2020, the speculative use of hydroxychloroquine for COVID-19 threatened its availability for people with established indications (malaria and auto-immune diseases). [69]The radiosensitizing and chemosensitizing properties of chloroquine are being evaluated for anticancer strategies in humans. [87] [88] In biomedicinal science, chloroquine is used for in vitro experiments to inhibit lysosomal degradation of protein products. Chloroquine and its modified forms have also been evaluated as treatment options for inflammatory conditions like rheumatoid arthritis and inflammatory bowel disease. [89]
Malaria is a mosquito-borne infectious disease that affects vertebrates and Anopheles mosquitoes. Human malaria causes symptoms that typically include fever, fatigue, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. Symptoms usually begin 10 to 15 days after being bitten by an infected Anopheles mosquito. If not properly treated, people may have recurrences of the disease months later. In those who have recently survived an infection, reinfection usually causes milder symptoms. This partial resistance disappears over months to years if the person has no continuing exposure to malaria. The mosquito vector is itself harmed by Plasmodium infections, causing reduced lifespan.
Mefloquine, sold under the brand name Lariam among others, is a medication used to prevent or treat malaria. When used for prevention it is typically started before potential exposure and continued for several weeks after potential exposure. It can be used to treat mild or moderate malaria but is not recommended for severe malaria. It is taken by mouth.
Antimalarial medications or simply antimalarials are a type of antiparasitic chemical agent, often naturally derived, that can be used to treat or to prevent malaria, in the latter case, most often aiming at two susceptible target groups, young children and pregnant women. As of 2018, modern treatments, including for severe malaria, continued to depend on therapies deriving historically from quinine and artesunate, both parenteral (injectable) drugs, expanding from there into the many classes of available modern drugs. Incidence and distribution of the disease is expected to remain high, globally, for many years to come; moreover, known antimalarial drugs have repeatedly been observed to elicit resistance in the malaria parasite—including for combination therapies featuring artemisinin, a drug of last resort, where resistance has now been observed in Southeast Asia. As such, the needs for new antimalarial agents and new strategies of treatment remain important priorities in tropical medicine. As well, despite very positive outcomes from many modern treatments, serious side effects can impact some individuals taking standard doses.
Clindamycin is a lincosamide antibiotic medication used for the treatment of a number of bacterial infections, including osteomyelitis (bone) or joint infections, pelvic inflammatory disease, strep throat, pneumonia, acute otitis media, and endocarditis. It can also be used to treat acne, and some cases of methicillin-resistant Staphylococcus aureus (MRSA). In combination with quinine, it can be used to treat malaria. It is available by mouth, by injection into a vein, and as a cream or a gel to be applied to the skin or in the vagina.
Mepacrine, also called quinacrine or by the trade names Atabrine or Atebrin, is a medication with several uses. It is related to chloroquine and mefloquine. Although formerly available from compounding pharmacies, as of August 2020 it is totally unavailable in the United States.
Artemether is a medication used for the treatment of malaria. The injectable form is specifically used for severe malaria rather than quinine. In adults, it may not be as effective as artesunate. It is given by injection in a muscle. It is also available by mouth in combination with lumefantrine, known as artemether/lumefantrine.
Primaquine is a medication used to treat and prevent malaria and to treat Pneumocystis pneumonia. Specifically it is used for malaria due to Plasmodium vivax and Plasmodium ovale along with other medications and for prevention if other options cannot be used. It is an alternative treatment for Pneumocystis pneumonia together with clindamycin. It is taken by mouth.
Plasmodium vivax is a protozoal parasite and a human pathogen. This parasite is the most frequent and widely distributed cause of recurring malaria. Although it is less virulent than Plasmodium falciparum, the deadliest of the five human malaria parasites, P. vivax malaria infections can lead to severe disease and death, often due to splenomegaly. P. vivax is carried by the female Anopheles mosquito; the males do not bite.
Hydroxychloroquine, sold under the brand name Plaquenil among others, is a medication used to prevent and treat malaria in areas where malaria remains sensitive to chloroquine. Other uses include treatment of rheumatoid arthritis, lupus, and porphyria cutanea tarda. It is taken by mouth, often in the form of hydroxychloroquine sulfate.
Dihydroartemisinin is a drug used to treat malaria. Dihydroartemisinin is the active metabolite of all artemisinin compounds and is also available as a drug in itself. It is a semi-synthetic derivative of artemisinin and is widely used as an intermediate in the preparation of other artemisinin-derived antimalarial drugs. It is sold commercially in combination with piperaquine and has been shown to be equivalent to artemether/lumefantrine.
Malaria prophylaxis is the preventive treatment of malaria. Several malaria vaccines are under development.
Tafenoquine, sold under the brand name Krintafel among others, is a medication used to prevent and to treat malaria. With respect to acute malaria, it is used together with other medications to prevent relapse by Plasmodium vivax. It may be used to prevent all types of malaria. It is taken by mouth.
Biocrystallization is the formation of crystals from organic macromolecules by living organisms. This may be a stress response, a normal part of metabolism such as processes that dispose of waste compounds, or a pathology. Template mediated crystallization is qualitatively different from in vitro crystallization. Inhibitors of biocrystallization are of interest in drug design efforts against lithiasis and against pathogens that feed on blood, since many of these organisms use this process to safely dispose of heme.
Haemozoin is a disposal product formed from the digestion of blood by some blood-feeding parasites. These hematophagous organisms such as malaria parasites, Rhodnius and Schistosoma digest haemoglobin and release high quantities of free heme, which is the non-protein component of haemoglobin. Heme is a prosthetic group consisting of an iron atom contained in the center of a heterocyclic porphyrin ring. Free heme is toxic to cells, so the parasites convert it into an insoluble crystalline form called hemozoin. In malaria parasites, hemozoin is often called malaria pigment.
The administration of drugs to whole populations irrespective of disease status is referred to as mass drug administration (MDA) or mass dispensing.
Pyronaridine is an antimalarial drug. It was first made in 1970 and has been in clinical use in China since the 1980s.
Piperaquine is an antiparasitic drug used in combination with dihydroartemisinin to treat malaria. Piperaquine was developed under the Chinese National Malaria Elimination Programme in the 1960s and was adopted throughout China as a replacement for the structurally similar antimalarial drug chloroquine. Due to widespread parasite resistance to piperaquine, the drug fell out of use as a monotherapy, and is instead used as a partner drug for artemisinin combination therapy. Piperaquine kills parasites by disrupting the detoxification of host heme.
Pregnancy-associated malaria (PAM) or placental malaria is a presentation of malaria in pregnancy which is life-threatening to both pregnant women and unborn fetuses. PAM occurs when a pregnant woman contracts malaria, generally as a result of Plasmodium falciparum infection, and because she is pregnant, is at greater risk of associated complications such as placental malaria. Placental malaria interferes with the transmission of vital substances through the fetal placenta, which can result in stillbirths, miscarriages, and dangerously low birth weights.
Drug repositioning is the repurposing of an approved drug for the treatment of a different disease or medical condition than that for which it was originally developed. This is one line of scientific research which is being pursued to develop safe and effective COVID-19 treatments. Other research directions include the development of a COVID-19 vaccine and convalescent plasma transfusion.
Chloroquine and hydroxychloroquine are anti-malarial medications also used against some auto-immune diseases. Chloroquine, along with hydroxychloroquine, was an early experimental treatment for COVID-19. Neither drug has been useful to prevent or treat SARS-CoV-2 infection. Administration of chloroquine or hydroxychloroquine to COVID-19 patients, either as monotherapies or in conjunction with azithromycin, has been associated with deleterious outcomes, such as QT prolongation. As of 2024, scientific evidence does not substantiate the efficacy of hydroxychloroquine, with or without the addition of azithromycin, in the therapeutic management of COVID-19.
There are no controlled data in human pregnancies.