Antimalarial drugs such as chloroquine, along with community hygiene measures, have significantly decreased malaria-associated mortality rates . However, it continues to be a challenge in developing countries.

In the following article, we will talk in detail about the best known antimalarial of all: chloroquine . We will mention its action, uses beyond malaria, possible adverse effects and when it should not be used.

What is chloroquine?

Malaria is the most significant parasitic disease worldwide, capable of claiming thousands of lives annually (1) . In this sense, chloroquine is a schizonticide antiparasitic drug , that is, it affects the blood schizont that causes the symptoms of patients.

Note: Chloroquine comes in presentations of chloroquine phosphate, in tablets of 100, 150, 200 and 250 mg, with oral route of administration. In addition, you can find its analogue on the market: hydroxychloroquine , also used as a treatment for malaria.

What is chloroquine used for?

Chloroquine is a medicine that is part of the group of antimalarials . However, its use is not limited to this, it can also be used in rheumatic conditions or infections by other parasites, as we will see below:

1. Malaria

Chloroquine is the treatment of choice against malaria, caused by strains of P. vivax , P. ovale and P. malariae. In this case, chloroquine is capable of eliminating the patient’s fever in a period of 24 to 48 hours.

Important: In children, a scheme of 25 mg/kg divided over 3 days is used . First, a dose of 10 mg/kg during the first two days and one of 5 mg/kg on the third day, according to the report of the Pan American Health Organization (PAHO) . (two)

2. Rheumatoid arthritis

Rheumatologic diseases such as rheumatoid arthritis can be treated with chloroquine or hydroxychloroquine, since the drug reduces inflammation by inhibiting immune action and the release of free radicals .

You should know: The initial dose is 200 mg per day. It is very important not to exceed the maximum dose (250 mg/day) , as it could cause retinopathy or ototoxicity (ear damage) in patients weeks after use.

3. Protozoan or helminth infections

A clear example of these infections is extraintestinal amoebiasis , caused by the protozoan Entamoeba Histolytica . In this case, the usefulness of chloroquine lies in its large volume of distribution (that is, penetrance into the tissues), managing to eliminate the parasites housed in the liver .

4. Collagen diseases

Sjögren’s syndrome and systemic lupus erythematosus (SLE) are some examples of these diseases. In fact, some studies on the rheumatological effects of the drug have reflected evidence in its favor. (3)

To highlight: Chloroquine decreases the production of interferon proinflammatory cytokines and prevents platelet aggregation, reducing the risk of thrombotic events in people with SLE. 

Chloroquine Side Effects

Chloroquine is a medication that should be used with extreme caution . Prolonged administration of this drug is associated with systemic adverse reactions as we will see below:

  • Hypersensitivity reactions.
  • Ocular alterations (blurred vision, changes in color perception).
  • Weightloss.
  • QT prolongation, cardiomyopathies and hypotension (low blood pressure).
  • Metabolic disorders, such as hypocalcemia (calcium deficiency) or hypoglycemia (low blood sugar).

Important: If you have any of the aforementioned symptoms, or any other not on the list, immediately stop using the medication and contact your treating doctor for more information.

Chloroquine Contraindications

Due to the high risk of a possible adverse effect , some of which are completely irreversible, chloroquine should not be used in people with the following conditions:

  • Known hypersensitivity to the drug.
  • Eye diseases .
  • Hematological disorders (porphyria).
  • Glucose-6-phosphate dehydrogenase deficiency.

You should know: You must inform the doctor about the health conditions that are suffered , thus avoiding unwanted reactions and to receive more information about therapeutic alternatives.

Key Findings

  • Chloroquine is an antimalarial drug, which is also indicated as a treatment in patients with rheumatic diseases .
  • Chloroquine comes in presentations of 100, 150, 200 and 250 mg tablets , taken orally.
  • The adverse effects of chloroquine include gastrointestinal, cardiovascular, and ocular disorders .
  • Chloroquine is contraindicated in patients with hypersensitivity , eye conditions, and hematologic disorders.

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