Table of Contents

  1. What is Chloroquine?
  2. Chloroquine composition
  3. History behind the Chloroquine
  4. Indications
  5. How does Chloroquine work? (Chloroquine Mechanism of Action)
  6. How to Take Chloroquine?
  7. Common Chloroquine Dose
  8. When to Avoid Chloroquine?
  9. Chloroquine Side Effects
  10. Effects on organs
  11. Warnings and Precautions
  12. Reported Allergic Reactions
  13. Effect of Chloroquine on the menstrual cycle
  14. Drug Interactions To Be Careful About
  15. Interactions with laboratory procedures
  16. Shows Effects / Results in (How Long Does the Effect Stay?)
  17. Is Chloroquine Addictive?
  18. Can I have Chloroquine with alcohol?
  19. Can I have Chloroquine When Pregnant?
  20. Can I have Chloroquine when feeding a baby?
  21. Can I drive after taking Chloroquine?
  22. Effect of an overdose of Chloroquine
  23. Effect of using expired Chloroquine
  24. Effect of missing a dose of Chloroquine
  25. Storage requirements
  26. Is Chloroquine Addictive?
  27. Substitutes

What is Chloroquine?

Chloroquine is an antimalarial drug generally used to treat and prevent malaria in the regions globally where there is sensitivity to malaria spread. Malaria is most commonly seen in Africa, South America, and Southern Asia.

Chloroquine Composition

The key constituents in this medication include Chloroquine Phosphate and basically available as Chloroquine 500 Mg Tablets and Chloroquine 250 Mg Tablets. 

History behind the Chloroquine

The history behind medicine is believed as initiated late in the 17th century itself. Indigenous people from Peru are known to extract the bark of the medicinal plant called Chinchona Officinalis to treat fever and chills in those days.

Again it was used in 1633 as herbal medicine in Europe to treat similar health issues including malaria. It was isolated as an antimalarial drug “Quinine” initially in 1820.

The actual Chloroquine was discovered by Hans Andersag and coworkers at the Bayer laboratories in the year 1934. They named it as Resochin. But it was not recognized well for a decade as it was then considered as more toxic to humans. Clinical trials to develop antimalarial medicine were sponsored by the United States government during World War II. As a result, Chloroquine got introduced as a prophylactic treatment for treating malaria in 1947.     

Drug Classification:

Chloroquine belongs to the class of drugs called Aminoquinolines which are used as Antimalarial agents.

Available Chloroquine Brand Names:

  • Aralen is one of the Chloroquine brand names with 2 sub-versions as Aralen Phosphate, Aralen Hydrochloride.
  • Chloroquine FNA, Resochin, Dawaquin, and Lariago are few other available Chloroquine Brand names.


Chloroquine Malaria Treatment

This medicine is basically intended to use for the prevention and treatment of malaria. However, it doesn’t prevent relapse in the case of vivax or ovale malaria. The reason behind this is, it is not efficient against exoerythrocytic forms of these parasites.

Chloroquine for Amebiasis Treatment

Apart from the treatment of malaria, it is also used in treating extra-intestinal amebiasis as a substitute to other medicine or along with some other medicine when the basic treatment for amebiasis fails with usage medicine such as metronidazole or nitroimidazole.  

Chloroquine for Rheumatoid Arthritis and Lupus Erythematosus

Chloroquine is used as an off label usage to treat autoimmune conditions like Rheumatoid Arthritis and lupus erythematosus as it has a mild suppressive effect on the immune system.

How does Chloroquine Work? (Chloroquine Mechanism of Action)

Chloroquine has a different mechanism of action depending on the condition it is used for.

In the case of Malaria:

In the human body red blood cells contain hemoglobin in which the globin part is the amino acid and hemo is the iron molecule. Malarial parasite damages the hemoglobin to acquire the globin part of the hemoglobin which is essential for its survival and growth. In this process, the parasite digests only the globin part and releases the heme part which is soluble and toxic to the parasite itself due to its porphyrin ring called Fe (II)-protoporphyrin IX (FP). To avoid self-damage the parasite biocrystallizes the toxic heme to non-toxic hemozine. Hemozine then gets collected in the digestive vacuole as insoluble crystals.  

When Chloroquine is administered, it enters the blood cells by simple diffusion then inhibits the parasite cell and digestive vacuole, then it becomes protonates and as the digestive vacuole is of acidic nature the Chloroquine cannot leave the digestive vacuole and thereby capping the bio crystallization of the heme molecules. As the accumulation of heme happens the Chloroquine binds to heme to form FP-Chloroquine complex is highly toxic to the parasite cell and disrupts the membrane function. As a result of FP-Chloroquine and FP (Fe (II)-protoporphyrin IX) cell damage and autodigestion of the parasite happens. Parasites that are not known to form hemozine are resistant to the medicine Chloroquine.

In the case of Antiviral treatment:

Chloroquine works by increasing the endosomal PH value, thereby impairing the cell fusion of the viral cell. In general low PH environment is needed for active growth of the viral cells.

Chloroquine for Rheumatoid Arthritis:

In the case of RA, Chloroquine works by inhibiting the action of auto-antigens that cause the inflammation by increasing the PH levels of these cytokines by inhibiting them.

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Chloroquine for COVID-19:

Usage of the Chloroquine for treating COVID-19 is not yet approved by the FDA and is under investigation stage only.

After the outbreak of Coronavirus in late January of 2020, the Chinese medical researchers stated about exploratory research about the Chloroquine and other two medicines called Remdesivir and Lopinavir, Ritonavir which seemed to have fairly good inhibitory effects on SARS-CoV-2, the virus that known to cause the COVID-19.

But there is no approval from the USFDA yet for this medicine to treat COVID-19. The Chinese, South Korea, and Italy used this medicine as an experimental basis only. Yet there is no clear declaration of the FDA about the official prescription use of the medicine. After the announcement of US President Donald Trump in the White House press meet on the 19th of March 2020. Yet the evidence is lacking whether the medicine can safely cure the new enemy SARS-CoV-2 (Coronavirus). Recently after his announcement Nigeria has announced two cases that got Chloroquine Poisoning, and Nigerian health officials had warned the Nigerian locals to not self-medicate with the drug. Hopefully, more research may be conducted about this medication to explore the possibilities, but everything as of now is a big question mark as the virus is rapidly spreading across the globe and the clinical research to approve any medicine by the FDA takes a certain good amount of time.

How to Take Chloroquine?

Chloroquine is available in the form of tablets and is prescribed to use orally. The dosage depends on the condition that is treated.

Common Chloroquine Dose

The common dosage depends on the condition it is prescribed. Follow the instructions by your doctor and never alter or suddenly stop the dosage without consulting your doctor.

When to Avoid Chloroquine?

It is advised to avoid this medication if there is

  • Hypersensitivity towards the Chloroquine, 4-aminoquinoline compounds.
  • In case of renal and visual related problems.
  • As prophylaxis in patients with a history of epilepsy.

Chloroquine Side Effects

Chloroquine may possibly show few side effects in some patients and is advised to consult your doctor immediately in case of such side effects without delay.

  • Blurred vision
  • Nausea
  • Vomiting
  • Abdominal cramps
  • Headache
  • Diarrhea
  • Skin discoloration
  • Liver health issues
  • Seizures
  • Behavioral changes

Effects on Organs

Chloroquine may possibly show adverse effects in the case of patients with cardiac, liver, and renal problems.

Warnings and Precautions

Chloroquine is advised to use with precautions under the strict medical supervision in few conditions considering the possible issues like –

Adverse Effects

  • Cardiovascular issues
  • Extrapyramidal effects
  • Hematologic effects
  • Hypoglycemia
  • Neuromuscular effects
  • Retinal toxicity

Disease-Related Issue

  • Auditory damage
  • Hepatic impairment
  • Porphyria
  • Psoriasis
  • Seizure

Reported Allergic Reactions

Chloroquine may possibly show some allergic reactions in rare cases and is advised to visit your doctor in case of such situations. Below mentioned are some possible allergic reactions of Chloroquine –

  • Hives                                                                                                                   
  • Difficult breathing
  • Swelling in face or throat
  • Fever
  • Sore throat
  • Burning in eyes
  • Skin rashes

Effect of Chloroquine on the Menstrual Cycle

Animal studies showed significant changes in the menstrual cycle. It is advised to use with doctor’s advice.

Chloroquine Drug Interactions to Be Careful About

Chloroquine may possibly show drug interaction with few medications. Below mentioned are some medications that Chloroquine may possibly show drug interactions.

  • Abiraterone Acetate
  • Agalsidase Alfa
  • Agalsidase Beta
  • Ampicillin
  • Androgens
  • Antacids
  • Antidiabetic Agents
  • Antipsychotic Agents like Phenothiazines
  • Aprepitant
  • Artemether
  • Cardiac Glycosides
  • Cholera Vaccine
  • Clofazimine
  • Dabrafenib
  • Domperidone
  • Tramadol
  • Vandetanib

This is not a comprehensive list and the medication may show drug interactions with other medications that are not listed here too. It is advised to share your current medication details if any with your doctor at the time of prescription to avoid complications.

Interactions with laboratory procedures

  • Chloroquine is known to cause hemolytic anemia, especially when used along with other drugs causing hemolysis.
  • It can cause hemolysis in patients with G6PD deficiency.

 Hence frequent monitoring is required.

Shows Effects / Results in (How Long Does the Effect Stay?)

It shows its effects within an hour after its administration. Chloroquine half-life is 20-60 days. It is excreted in the urine.

Is Chloroquine Addictive?

No adequate studies are available regarding the addiction to Chloroquine.

Can I have Chloroquine with alcohol?

Chloroquine, in general, may cause dizziness or blurred vision and if it is used along with alcohol, it may possibly show adverse effects. Hence it is not advised to use along with alcohol.

Can I have Chloroquine When Pregnant?

Chloroquine is known to pass through the placenta and discovered to be present in urinals of newborns. In general, symptoms of malarial infection in pregnancy are more severe compared to non-pregnant women and the chances of perinatal and maternal morbidity or mortality are high. Hence it is advised to use this medication only if is absolutely unavoidable and with proper medical supervision.   

Can I have Chloroquine when feeding a baby?

Chloroquine is known to pass into the milk and the effect of the passed medication on infants is unknown. Hence it is advised to consult your doctor if you are a feeding mother to avoid further complications.

Can I drive after taking Chloroquine?

Chloroquine may possibly cause blurred vision and dizziness which may even worsen if used along with alcohol. Hence it is not advised to do activities like driving and operating heavy machinery etc.

Effect of an overdose of Chloroquine

Overdosage of Chloroquine may cause some serious effects, hence it is advised to follow the dosage schedule as per prescription only. It may possibly show some side effects of overdosage like –

  • Decrease in urination
  • Drowsiness
  • Dry mouth
  • Increased or decreased pulse rate
  • Loss of appetite
  • Muscle cramps
  • Numbness or tingling sensation of limbs, and lips

Effect of using expired Chloroquine

Advised to not use an expired medication and check the dates properly while purchasing and also while administering the medication.

Effect of missing a dose of Chloroquine

Not advised to take an excess dose if a dose is missed and if it is nearing the next dose schedule but to continue with the next regular dose.  

Storage requirements

This medicine is advised to store at room temperature and away from direct sunlight as in the case of any other medicine. Keep it away from reach to children. The accidental ingestion of this medicine by children has shown fatal reactions.

Substitutes for Chloroquine

  • Primaquine
  • Qualaquin (Quinine)
  • Mefloquine (Larium)
  • Pyrimethamine
  • Artimisinin



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