Chloroquine is a medication primarily used to prevent and treat malaria. It also has applications in treating autoimmune diseases like rheumatoid arthritis and lupus. As an
antimalarial drug, chloroquine works by interfering with the growth of parasites within the red blood cells.
Chloroquine toxicity can occur through various pathways, primarily due to
overdose or chronic use. The drug is rapidly absorbed in the gastrointestinal tract, and its high lipid solubility allows it to accumulate in tissues such as the liver, spleen, kidney, and lungs. The risk of acute toxicity is heightened when high doses are taken, either accidentally or intentionally, which can lead to severe
cardiotoxicity.
The symptoms of chloroquine toxicity can vary based on the dose and duration of exposure. Acute toxicity is characterized by nausea, vomiting, dizziness, and vision changes. Severe cases can lead to
cardiac arrest, seizures, and coma. Chronic toxicity, often seen in patients using chloroquine long-term, can result in retinopathy, which can lead to
vision impairment or blindness.
Diagnosing chloroquine toxicity involves a combination of clinical evaluation and laboratory tests. Blood tests can measure the
serum levels of chloroquine, although these levels do not always correlate with toxicity due to the drug's extensive tissue distribution. Electrocardiograms (ECGs) are crucial for detecting cardiac effects, such as QT interval prolongation, which are indicative of toxicity.
Treating chloroquine toxicity requires prompt medical intervention. Initial management includes stabilization of the airway, breathing, and circulation. Activated charcoal may be administered if the patient presents within 1-2 hours of ingestion to limit absorption. In cases of severe toxicity, especially with cardiac involvement, intravenous
diazepam and epinephrine may be used to mitigate cardiac complications. Supportive care in an intensive care unit is often necessary.
Preventive measures for chloroquine toxicity emphasize proper dosing and monitoring, particularly in long-term use for autoimmune disorders. Patients should be educated on the importance of adhering to prescribed doses and the potential risks of
self-medication. Regular ophthalmologic examinations are recommended for individuals on prolonged chloroquine therapy to monitor for early signs of retinopathy.
Chloroquine has been used since the mid-20th century, and its extensive use has led to well-documented cases of
drug resistance in malaria-endemic regions. The COVID-19 pandemic brought renewed attention to chloroquine as a potential treatment, leading to increased reports of toxicity due to misuse and overprescription. This highlights the importance of understanding the
pharmacokinetics and safety profile of chloroquine.
Conclusion
Understanding chloroquine toxicity is essential for healthcare providers and patients alike. While it remains a valuable medication for certain conditions, its potential for serious toxicity necessitates careful management and adherence to dosing guidelines. Ongoing research and
pharmacovigilance are crucial in ensuring the safe use of chloroquine, particularly as new therapeutic contexts emerge.
