Antimalarial medications are a primary treatment for lupus, an autoimmune condition. Originally developed to combat malaria, their effectiveness in managing lupus was discovered during World War II. These drugs are classified as disease-modifying antirheumatic drugs (DMARDs), meaning they regulate the immune system for long-term use. They are prescribed to control symptoms, reduce disease activity, and prevent flare-ups, improving the quality of life for those with this chronic condition.
Mechanism of Action in Lupus
Antimalarials modulate the body’s immune response, which is different from their effect on the malaria parasite. They interfere with cellular components called toll-like receptors (TLRs). In lupus, certain TLRs are overly active, leading to the production of inflammatory proteins like interferon. By blocking these receptors, antimalarials reduce the inflammatory signals that drive the disease.
These medications also affect parts of the cell known as lysosomes. Antimalarials increase the pH inside these structures, making them less acidic. This change disrupts antigen presentation, where immune cells display protein fragments to trigger an attack. Hindering this process helps calm the autoimmune response where the body targets its own tissues.
The drugs interfere with pathways that lead to inflammation without broadly suppressing the immune system, which is why they do not increase the risk of infection. This effect results in a stabilization of the underlying disease process in lupus.
Specific Antimalarial Drugs Prescribed
The most commonly prescribed antimalarial for lupus is hydroxychloroquine (Plaquenil), which is the standard for long-term therapy in patients with systemic lupus erythematosus (SLE). Another antimalarial, chloroquine (Aralen), is also used but is prescribed less frequently. A third option, quinacrine, may be considered in specific situations, sometimes in combination with other antimalarials for difficult-to-treat skin manifestations.
Hydroxychloroquine is the preferred choice due to its better safety profile compared to chloroquine. The selection of a specific antimalarial is based on the individual patient’s disease activity and risk factors.
Clinical Benefits for Lupus Patients
Antimalarials provide a wide range of benefits, including reducing the frequency and severity of lupus flares by as much as 50%. They are also effective for cutaneous lupus erythematosus (CLE), helping to clear up skin lesions. Patients often experience relief from common symptoms, including:
- Joint pain
- Muscle aches
- Skin rashes
- Fever
- Fatigue
Beyond symptom control, antimalarials offer protective effects against organ damage to the kidneys and central nervous system. For patients with lupus nephritis, hydroxychloroquine is associated with improved remission rates and a lower risk of progressing to end-stage kidney disease. These drugs also reduce the risk of blood clots, a serious complication for some individuals with lupus, especially those with antiphospholipid antibodies.
These medications are sometimes considered a form of long-term “lupus life insurance” because they help manage the disease over many years. Their consistent use is linked to increased long-term survival rates for patients. Additional benefits may include lower cholesterol and blood glucose levels.
Managing Side Effects and Monitoring
While antimalarials are safe for long-term use, they carry a risk of side effects that requires careful management. The most serious, though rare, side effect is damage to the retina, a condition known as retinopathy. This can lead to irreversible vision loss if not detected early. The risk is low, affecting about one in 5,000 people taking hydroxychloroquine within the first five years.
The risk of retinal damage is cumulative and increases with the duration of treatment and the daily dose. Because of this, monitoring is a standard part of the treatment protocol. A baseline eye exam with an ophthalmologist is required before or shortly after a patient starts taking an antimalarial to establish a reference point for retinal health.
Following the baseline exam, annual screenings are recommended, beginning after five years of continuous use. These check-ups involve specialized tests to detect the earliest signs of retinal changes before symptoms appear. Other common side effects are mild and can include gastrointestinal issues like nausea or diarrhea, and skin discoloration.