Other Names/Brands

Aluquine, Esele, Farneltik, Hydroxin, Hydroxychloroquine Sulfate, Hyloquin, Kalquine, Sanloquin

Mechanism of Action

Hydroxychloroquine works by modulating the immune system and has anti-inflammatory effects. This drug was originally used to treat malaria, but it is also effective in treating autoimmune diseases such as lupus and rheumatoid arthritis.

Hydroxychloroquine works by inhibiting enzyme activity and processes within immune cells, such as inhibiting the production of pro-inflammatory cytokines and reducing T-cell activity. Furthermore, hydroxychloroquine can increase the pH within cells and intracellular vesicles, which interferes with viral replication and certain immune processes.

Indications

Hydroxychloroquine is indicated for the treatment and prevention of malaria caused by the Plasmodium parasite. It is also used to manage autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis due to its anti-inflammatory and immunomodulatory effects. In these conditions, hydroxychloroquine helps reduce inflammation, joint pain, and other systemic symptoms.

Contraindications

Hydroxychloroquine is contraindicated in patients with a history of hypersensitivity to hydroxychloroquine or similar drugs such as chloroquine. This drug should also not be used in patients with retinal disorders or visual impairment related to the use of 4-aminoquinoline compounds, as it may worsen these conditions. Furthermore, use should be avoided in patients with certain heart conditions, such as QT interval prolongation, due to the risk of serious arrhythmias.

Side Effects

Side effects of hydroxychloroquine can vary, ranging from mild to serious. Common side effects include nausea, vomiting, stomach pain, and headache. In some cases, this drug can cause vision problems due to retinal toxicity, especially with long-term use or high doses.

Other serious side effects include heart rhythm disturbances (arrhythmias), low blood sugar levels, and muscle and nerve disorders. Therefore, regular medical monitoring is important while taking hydroxychloroquine.

Preparations

Hydroxychloroquine is available as an oral tablet. Each tablet typically contains 200 mg of hydroxychloroquine sulfate, which is equivalent to approximately 155 mg of hydroxychloroquine base.

This medication is taken orally once or twice daily, depending on the condition being treated and your doctor's recommendation. This preparation is designed for short-term or long-term use, depending on the medical indication, such as malaria, lupus, or rheumatoid arthritis.

Dosage

The dosage of hydroxychloroquine varies depending on the indication. For malaria prevention in adults, the typical dose is 400 mg once weekly, starting one to two weeks before exposure and continuing for four weeks after returning from an endemic area.

For the treatment of lupus erythematosus or rheumatoid arthritis, the initial dose is usually 400–600 mg per day, which can then be reduced to a maintenance dose of 200–400 mg per day depending on the patient's response and tolerance. The dose should be adjusted based on the patient's weight and medical condition and monitored by a healthcare professional to prevent serious side effects, especially with long-term use.

Safety of Drugs

Hydroxychloroquine is classified as a pregnancy safety category C by the FDA, meaning animal studies have shown adverse effects on the fetus, but there are no adequately controlled studies in humans. Therefore, use of this drug during pregnancy is only recommended if the expected benefits outweigh the potential risks.

In some cases of autoimmune diseases, such as lupus, hydroxychloroquine may still be prescribed during pregnancy because it can help control the disease and prevent complications. Its use should always be monitored by a medical professional.

Drug Interactions

Hydroxychloroquine has potential drug interactions that require attention, especially when used with other medications that affect heart rhythm, such as those that can prolong the QT interval (e.g., amiodarone, azithromycin, or certain antipsychotics), as this can increase the risk of serious arrhythmias.

Hydroxychloroquine can interact with antidiabetic medications and enhance their blood sugar-lowering effects, potentially increasing the risk of hypoglycemia. Interactions can also occur with antiepileptic drugs, digoxin, and some antibiotics. Therefore, it is important to inform your healthcare provider about all medications you are currently taking before starting hydroxychloroquine therapy.

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