Hydroxychloroquine

Malaria Prevention and Treatment

Hydroxychloroquine is used to prevent and treat malaria, an infection caused by parasites that enter the body through the bite of an infected mosquito. It is typically used for malaria in areas where the parasites have not developed resistance to similar medications.

Autoimmune Conditions

This medication is also prescribed to treat several autoimmune disorders, including:

• Systemic lupus erythematosus (SLE): A condition where the immune system attacks the body's own tissues.
• Discoid lupus erythematosus (DLE): A chronic skin condition involving sores and inflammation.
• Rheumatoid arthritis: A condition that causes pain, swelling, and stiffness in the joints.

In these cases, hydroxychloroquine is often used when other treatments have not been effective.

COVID-19

While hydroxychloroquine was studied as a potential treatment for COVID-19, clinical trials have shown it is not effective for this use. The U.S. Food and Drug Administration (FDA) has cautioned against using the drug for COVID-19 outside of a hospital setting or a clinical trial due to the risk of serious heart rhythm problems and other safety concerns.

Treating Malaria

Hydroxychloroquine belongs to a class of medications known as antimalarials. When used for malaria, it works by killing the parasites that cause the infection. It can be used to prevent malaria in people traveling to areas where the disease is common, or to treat an active infection.

Treating Autoimmune Conditions

For conditions like rheumatoid arthritis and systemic lupus erythematosus, hydroxychloroquine is classified as a disease-modifying antirheumatic drug (DMARD). While its exact mechanism for these conditions is not fully understood, it is believed to work by:

• Modulating the immune system: It may interfere with the communication between cells in the immune system.
• Reducing inflammation: By affecting the immune response, it helps decrease the inflammation, pain, and swelling associated with these diseases.
• Preventing flares: In lupus, it helps reduce the frequency of symptom flare-ups and may prevent long-term organ damage.

Because it targets the underlying disease process rather than just the symptoms, it may take several weeks or months of consistent use before the full benefits are noticed.

Common Side Effects

Many people using hydroxychloroquine experience mild symptoms that may go away as the body adjusts to the medication. These include:

• Nausea, vomiting, or stomach cramps
• Diarrhea
• Loss of appetite
• Headache
• Dizziness
• Skin rash or itching
• Hair loss

Serious Side Effects

Seek medical attention immediately if you experience any of the following serious symptoms:

• Vision changes: Blurred vision, seeing light flashes or halos, difficulty reading, or any other changes in eyesight. Long-term use may lead to permanent damage to the retina.
• Heart rhythm issues: Fast, pounding, or irregular heartbeat and fainting. These risks may increase if the drug is taken with certain other medications.
• Mental health and mood: New or worsening anxiety, depression, irritability, or thoughts of self-harm.
• Muscle and nerve problems: Unexplained muscle weakness, tingling, or numbness in the hands or feet.
• Hearing problems: Ringing in the ears or sudden hearing loss.
• Low blood sugar: Symptoms such as sweating, shakiness, hunger, or confusion.
• Severe skin reactions: Redness, blistering, or peeling of the skin, which may be accompanied by a fever.
• Blood system changes: Unusual bleeding, bruising, or signs of infection such as a persistent sore throat and fever.

Vision Changes

Long-term use or high doses of hydroxychloroquine can cause irreversible damage to the retina, the part of the eye that helps with vision. This condition, known as retinopathy, may lead to permanent vision loss. Regular eye examinations are typically recommended before starting treatment and periodically during therapy.

Heart Risks

Hydroxychloroquine can cause serious heart rhythm problems, such as QT prolongation, which can be life-threatening. These risks may increase if the medication is taken with other drugs that affect heart rhythm, such as azithromycin. It has also been linked to heart failure and cardiomyopathy.

Blood Sugar Levels

This medication may cause severe hypoglycemia (dangerously low blood sugar), even in patients who do not have diabetes. Symptoms can include sudden sweating, shaking, or confusion. If severe low blood sugar occurs, treatment may need to be stopped.

Mental Health and Neurological Effects

Some people taking hydroxychloroquine have reported mood changes, suicidal thoughts, or other psychiatric symptoms. It can also cause muscle weakness or nerve damage, particularly with long-term use.

Other Precautions

• Skin Reactions: Severe and potentially fatal skin reactions, such as Stevens-Johnson syndrome, have been reported.
• Blood Disorders: The drug may cause low blood cell counts, including anemia or a decrease in white blood cells.
• Psoriasis and Porphyria: Hydroxychloroquine may worsen these conditions.
• COVID-19: The FDA cautions against using hydroxychloroquine for COVID-19 outside of a hospital setting or clinical trial due to the risk of serious heart rhythm problems.

Pregnancy

The decision to use hydroxychloroquine during pregnancy often depends on the condition being treated. For individuals with autoimmune diseases like lupus or rheumatoid arthritis, healthcare providers may recommend continuing the medication because a disease flare can pose significant risks to both the parent and the pregnancy. When used for malaria prevention, the risks of contracting malaria are generally considered more dangerous to the fetus than the medication itself.

While some research suggests that hydroxychloroquine does not significantly increase the risk of major birth defects, the available data is limited. It is essential to discuss the potential risks and benefits with a doctor if you are pregnant or planning to become pregnant.

Breastfeeding

Hydroxychloroquine passes into breast milk in small amounts. Because the medication stays in the body for a long time, it can accumulate in a nursing infant. While many clinical guidelines consider the use of hydroxychloroquine to be compatible with breastfeeding, the long-term effects on the infant are not fully known. Parents should consult with their healthcare provider to evaluate the safety of breastfeeding while taking this medication.

Available Forms

Hydroxychloroquine is primarily available in the following form:

• Oral Tablet: This medication is manufactured as a tablet intended for oral administration.

While the medication is standardly produced as a solid tablet, healthcare providers or pharmacists may sometimes provide instructions for alternative administration methods for patients who have difficulty swallowing tablets.

FDA-Approved Indications

The U.S. Food and Drug Administration (FDA) has approved hydroxychloroquine for the following medical uses:

• Treatment and prevention of malaria in areas where chloroquine resistance is not present.
• Treatment of systemic lupus erythematosus and discoid lupus erythematosus.
• Treatment of acute and chronic rheumatoid arthritis in adults.

COVID-19 Regulatory History

In early 2020, the FDA issued an Emergency Use Authorization (EUA) for hydroxychloroquine to treat COVID-19. However, the FDA revoked this authorization in June 2020 after clinical trial data indicated the drug was unlikely to be effective for this use and that its potential benefits did not outweigh the known risks.

The FDA currently cautions against using hydroxychloroquine for COVID-19 outside of a hospital setting or a formal clinical trial. This caution is based on reports of serious heart rhythm problems and other safety concerns.

Safety Communications

The FDA has issued safety communications regarding the risk of serious heart-related adverse events associated with hydroxychloroquine. These risks include:

• QT interval prolongation, which can lead to life-threatening heart rhythms.
• Ventricular tachycardia and ventricular fibrillation.
• Increased risk of heart rhythm issues when used in combination with other medications, such as azithromycin.

The FDA Adverse Event Reporting System (FAERS) has also identified potential signals of serious risks, including neuropsychiatric events and severe skin reactions, which the agency continues to monitor.

Effectiveness and Safety

While hydroxychloroquine was initially studied as a potential treatment for COVID-19, large-scale clinical trials have demonstrated that the drug does not provide a clinical benefit for treating or preventing the virus. Consequently, the U.S. Food and Drug Administration (FDA) revoked the Emergency Use Authorization (EUA) that previously allowed its use for certain hospitalized patients with COVID-19.

FDA Warnings

The FDA has issued warnings against using hydroxychloroquine for COVID-19 outside of a hospital setting or a formal clinical trial. Using the medication for this purpose can lead to severe health risks, including:

• Serious heart rhythm problems, such as QT interval prolongation.
• Ventricular tachycardia or fibrillation.
• Increased risk of heart-related death, particularly when used in combination with the antibiotic azithromycin.

Other potential risks include severe liver and kidney issues, as well as blood glucose disturbances. Because the known and potential risks outweigh the lack of proven benefits, health authorities advise against its use for COVID-19.