chloroquine

chloroquine. It is a medication primarily used to prevent and treat malaria in areas where the parasite remains sensitive to its effects. The drug is also employed in the treatment of certain autoimmune conditions, such as rheumatoid arthritis and lupus erythematosus. Discovered in 1934, it became a cornerstone of global antimalarial programs for decades.

History

The compound was first synthesized in 1934 by Hans Andersag and his colleagues at the German pharmaceutical company Bayer. Its significant antimalarial potential was not fully recognized until after World War II, when American researchers evaluated it as part of the U.S. Army's antimalarial research program. Large-scale use began in the late 1940s, revolutionizing malaria control and becoming a key component of the World Health Organization's Global Malaria Eradication Programme. Widespread resistance in the malaria parasite Plasmodium falciparum first emerged in the late 1950s in regions like Southeast Asia and South America, severely limiting its therapeutic utility for this disease.

Medical uses

Its primary licensed use is for the prophylaxis and treatment of uncomplicated malaria caused by Plasmodium vivax, Plasmodium ovale, and sensitive strains of Plasmodium falciparum. It is also a standard therapy for the autoimmune disorder lupus erythematosus, particularly for cutaneous and joint manifestations. In rheumatoid arthritis, it is often used in combination with other disease-modifying antirheumatic drugs like methotrexate. Furthermore, it has been used off-label in the management of conditions such as porphyria cutanea tarda and Q fever.

Adverse effects

Common side effects include gastrointestinal disturbances like nausea and diarrhea, as well as headache, blurred vision, and pruritus. More serious adverse effects are associated with long-term use or high doses, notably irreversible retinopathy that can lead to vision loss, requiring regular monitoring by an ophthalmologist. Other significant risks include cardiomyopathy, myopathy, and severe neuropsychiatric events. Acute overdose can be rapidly fatal, causing cardiovascular collapse and seizures, an issue highlighted in reports from the American Association of Poison Control Centers.

Pharmacology

The drug is a 4-aminoquinoline compound that concentrates in the acidic food vacuoles of malaria parasites, where it interferes with the detoxification of heme, leading to parasite death. In autoimmune diseases, its mechanism is thought to involve raising the pH within intracellular compartments, interfering with antigen presentation and cytokine production. It is well-absorbed after oral administration, extensively distributed into tissues, and metabolized in the liver by enzymes such as CYP2C8, with a very long elimination half-life.

Society and culture

It is on the World Health Organization's List of Essential Medicines. During the COVID-19 pandemic, it and its derivative hydroxychloroquine became the subject of intense global controversy and political debate, notably promoted by figures like Donald Trump despite a lack of robust evidence from organizations like the Food and Drug Administration and the European Medicines Agency. This period saw emergency use authorizations, subsequent revocations, and widespread media coverage, influencing public perception and drug policy. The drug has also appeared in popular culture, including mentions in novels by John le Carré.

Research

Ongoing investigation explores its potential antiviral properties against viruses like Zika virus and Chikungunya virus, though results have been inconclusive. Research continues into its role as a sensitizing agent in certain cancer therapies and its immunomodulatory effects in diseases like Sjögren's syndrome. A major focus remains on understanding and combating antimicrobial resistance, particularly through studies conducted by institutions like the National Institutes of Health and the Wellcome Trust.