Antimalarial agents are medications used to treat malaria, an infection with a single-celled parasite, and several other conditions, including those associated with skin disorders. Scientists are not exactly sure how these drugs effectively treat skin conditions, but believe that they inhibit skin reactions to ultraviolet light, suppress the immune system and reduce inflammation. It is also believed that antimalarials may work by binding to the genetic material in cells, such as deoxyribonucleic acid (DNA).
Numerous antimalarial agents are used to treat malaria, a disease that occurs in tropical areas and is extremely rare in the United States. The U.S. Food and Drug Administration (FDA) has also approved antimalarial agents to treat one dermatologic condition, lupus erythematosus. However, physicians may also prescribe them for other skin-related disorders, including dermatomyositis, sarcoidosis and solar urticaria. Three antimalarial agents currently are used to treat dermatologic disorders: chloroquine, hydroxychloroquine and quinacrine (which is not widely available in the United States).
Patients who take antimalarial agents must be sure to use them exactly as prescribed by a physician. An overdose of an antimalarial agent can result in acute poisoning that can be fatal.
About antimalarial agents
Antimalarial agents are medications used chiefly to treat malaria, an infection with a single-celled parasite. However, they are also prescribed to treat several other conditions, including those associated with skin disorders.
Malaria occurs mostly in tropical and subtropical areas, especially in Africa, Asia, South America and Central America. In the United States, the disease has almost been eradicated. Nonetheless, each year hundreds of Americans get the disease while traveling overseas and are treated with antimalarial drugs.
In addition, several conditions that cause symptoms in the skin can be treated with antimalarial agents. Scientists are not exactly sure how antimalarial agents work to treat skin conditions. However, it is believed that antimalarials inhibit skin reactions to ultraviolet light, suppress the immune system and reduce inflammation. It is also believed that antimalarials may work by binding to the genetic material in cells, such as deoxyribonucleic acid (DNA). Antimalarial agents are sometimes used in conjunction with oral corticosteroids for certain skin conditions.
Because of the risk for side effects, people taking antimalarial agents must be monitored with blood tests, including CBC and liver function tests. Frequent eye exams (every three to six months) are also recommended.
Types and differences of antimalarial agents
Several different kinds of antimalarial agents are prescribed to fight malaria. These medications are given either orally or intravenously, depending on the severity of infection. In some countries, antimalarial agents are given as suppositories.
Three antimalarial agents are currently used to treat skin disorders: chloroquine, hydroxychloroquine and quinacrine. Chloroquine and hydroxychloroquine are the most commonly used medications. They are derivatives of quinine, an alkaloid obtained from the bark of the cinchona tree in South America. Quinine has been used as an antimalarial agent since the 1800s.
Quinacrine is difficult to obtain in the United States. Recently, several individual pharmacies have been compounding quinacrine and offering it by mail order.
Uses
Generic Name
Brand Name(s)
Skin
chloroquine
Aralen
hydroxychloroquine
Plaquenil
quinacrine
n/a
Other
doxycycline
Doryx, Vibramycin
atovaquone and
proguanil combination
Malarone
sulfadoxine and
pyrimethamine combination
Fansidar
mefloquine
Lariam
quinine sulfate
n/a
Conditions treated with antimalarial agents
The U.S. Food and Drug Administration (FDA) has approved antimalarial agents for treatment of one skin condition, lupus erythematosus. A chronic, inflammatory autoimmune disorder, lupus erythematosus often causes a "butterfly" rash over the cheeks and bridge of the nose made worse by sun exposure. Antimalarial agents are sometimes used to treat this condition in patients who do not respond to other measures, including sunscreens and topical corticosteroids. Antimalarial agents have been shown to improve skin problems, joint problems and ulcers associated with the condition.
Physicians also sometimes prescribe antimalarial medications, such as hydroxychloroquine or chloroquine phosphate, to treat other conditions that affect the skin. These disorders include:
Solar urticaria. Hives that appear on parts of the body within a few minutes of exposure to the sun.
Morphea. A rare, localized form of scleroderma marked by oval-shaped patches that are red or purple and that often develop a whitish center.
Sjögren syndrome. A disorder of the immune system that causes symptoms such as dry eyes, dry mouth, and skin rash or dry skin (xerosis). Hydroxychloroquine is sometimes prescribed to treat this condition.
Sarcoidosis. Disease in which inflammation occurs in the skin, lymph nodes, lungs, liver, eyes or other tissues.
Dermatomyositis. A rare disease marked by muscle weakness and a skin rash. Antimalarial medications are sometimes prescribed to treat cases of persistent rash.
Porphyria cutanea tarda. Characterized by sensitivity to the sun, this condition results from underactivity of the enzyme uroporphyrinogen decarboxylase (UROD). Individuals with this condition develop blistering, scarring, changes in pigmentation and increased hair growth when their skin is exposed to the sun.
Aside from their use in treating various skin-related conditions, antimalarial agents are chiefly used to treat or prevent malaria. This disease occurs when humans are infected by a single-celled parasite (Plasmodium) through a mosquito bite. There are only four species of the Plasmodium parasite that can cause malaria. They live in mosquitoes in tropical and subtropical areas of Africa, Asia, and Central and South America. Patients with malaria experience fever and chills that comes in recurrent attacks. Left untreated, the disease can be deadly.
In addition to treating already existing malaria, antimalarial agents are often prescribed to prevent the disease. People who are traveling overseas to an area where malaria is common may take antimalarial agents before, during and after their trip.
Potential side effects of antimalarials
Some patients who take antimalarial medications may find that their skin is more sensitive to sunlight. Special precautions may be necessary to ensure that skin is not sunburned during this time. In addition, some patients who take antimalarial agents for four months or longer find that their skin temporarily takes on a bluish-gray to black tint. This typically affects the shins, face, palate or nail beds. Progressive bleaching of the hair roots of the scalp or face also may occur. These effects are reversible with cessation of therapy.
Other side effects associated with antimalarials include dry skin (xerosis), itchy skin (pruritus), skin rash, stomach upset, loss of appetite, nausea, vomiting, diarrhea, headache, nervousness, irritability, dizziness, mild hair loss and difficulty sleeping.
Patients with psoriasis may experience severe flare-ups while taking antimalarial drugs. Antimalarial drugs belong to a class of drugs known as disease-modifying antirheumatic drugs (DMARDs) and may be prescribed to help minimize joint damage that occurs in psoriatic arthritis and rheumatoid arthritis. Again, these drugs may cause severe psoriasis flare-ups in people who take them to treat psoriatic arthritis. Hydroxychloroquine is less likely to cause these flare-ups than other antimalarials.
Patients who have been treated with antimalarial agents may feel very weak and tired afterward. It may take a few weeks before a patient recovers completely.
Individuals experiencing severe or persistent side effects should contact their physician. Patients should contact their physician immediately if any of the following signs or symptoms occur:
These signs and symptoms may signal a serious adverse reaction, such as damage to the retina (the tissue that lines the inside of the eye) or myopathy (a disorder or disease of the skeletal muscles).
Conditions of concern with antimalarials
Antimalarial agents should not be taken by anyone who has had a previous reaction to using the drug. In addition, patients who have a G6PD (glucose-6-phosphate dehydrogenase) deficiency should not take antimalarial drugs such as chloroquine, isoniazid or primaquine, which is sometimes used to treat patients infected with a specific Plasmodium parasite that can lie dormant in the liver. A screening test is available to help determine whether or not patients have this deficiency.
Other conditions that may prevent use of antimalarial agents include:
Myasthenia gravis (neuromuscular disorder characterized by muscle weakness)
Psoriasis
Retinal changes or changes to visual field
Severe blood disease
Alcoholism
Significant liver dysfunction
Significant neurological disorders
Auditory damage
In addition, antimalarials may not be recommended for women who are pregnant, planning to become pregnant or breastfeeding.
Drug or other interactions with antimalarials
Patients should consult their physician before taking any additional prescriptions, over-the-counter medications, nutritional supplements or herbal medications.
Kaolin (diarrhea drug) and magnesium trisilicate (antacid) may decrease absorption of both chloroquine and hydroxychloroquine. Chloroquine may interfere with antibody response to intradermal human diploid cell rabies vaccine. Cimetidine, which is used to treat duodenal ulcers, may reduce oral clearance and metabolism of chloroquine. Use of the cardiac drug digoxin with hydroxychloroquine may increase serum digoxin levels.
Symptoms of antimalarial agent overdose
Patients who take greater than recommended levels of an antimalarial agent are at risk for acute poisoning that can be fatal. This often manifests as irreversible cardiac arrest within several hours of ingesting excess dosage of the drug. Symptoms may first appear within 30 minutes and include headache, drowsiness, visual changes and seizures. Patients who experience these symptoms should seek immediate medical treatment, which usually includes induced vomiting or flushing the stomach with water, followed by administration of activated charcoal (which prevents poison from being absorbed into the body).
Pregnancy use issues with antimalarial agents
The U.S. Food and Drug Administration has classified most antimalarials as unrated, which means they have not been assigned a risk level related to pregnancy. Experts disagree about the potential harm to a fetus or breastfeeding newborn (antimalarial agents are secreted in breast milk) posed by a mother’s use of antimalarial agents. However, many studies have suggested that chloroquine and hydroxychloroquine should not be taken by pregnant women. As a result, women generally are urged not to take antimalarial agents during pregnancy or nursing.
Women who discover they are pregnant while taking antimalarial agents should consult with their physician about whether or not they should immediately discontinue therapy or finish the treatment regimen.
Child use issues with antimalarial agents
For many years, experts suggested that children should not take antimalarial agents, because it was believed that they had a much greater risk of toxicity. However, in recent years studies have shown that children may not face greater risks in using antimalarial agents than adults as long as dosage levels are appropriate for their age and size. Parents should discuss with their child’s physician whether the benefit of taking antimalarial medications outweighs any potential risk to their child’s health.
Questions for your doctor about antimalarials
Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to antimalarial agents:
Are antimalarials safe for me to take?
How and when should I take this drug?
What should I do if I miss a dose?
What side effects may I develop?
For what side effects should I seek medical attention?
How long will it take for the drug to take effect?
How long will I have to take this drug?
Are there medications, nutritional supplements or herbal medications I should avoid while taking this drug?
How will I know if the drug is working?
What are other possible treatments if the drug does not work?
