Antimalarial drugs are used for the treatment and prevention of malaria infection. Most antimalarial drugs target the erythrocytic stage of malaria infection, which is the phase of infection that causes symptomatic illness. The extent of pre-erythrocytic (hepatic stage) activity for most antimalarial drugs is not well characterized.

Treatment of the acute blood stage infection is necessary for malaria caused by all malaria species. In addition, for infection due to Plasmodium ovale or Plasmodium vivax, terminal prophylaxis is required with a drug active against hypnozoites (which can remain dormant in the liver for months and, occasionally, years after the initial infection).

The mechanisms of action, resistance, and toxicities of antimalarial drugs will be reviewed here. Use of these agents for prevention and treatment of malaria is discussed in detail separately. (See "Prevention of malaria infection in travelers" and "Treatment of severe malaria" and "Treatment of uncomplicated falciparum malaria in nonpregnant adults and children".)

ARTEMISININ DERIVATIVES

The artemisinins are derived from the leaves of the Chinese sweet wormwood plant, Artemisia annua. They have been used in China for the treatment of malaria for over 2000 years and came to attention outside of China in the 1970s and 1980s. Artemisinin formulations include artemether, arteether, dihydroartemisinin, and artesunate. They are marketed as part of combination therapy throughout the world.

Artemisinins appear to act by binding iron, breaking down peroxide bridges, leading to the generation of free radicals that damage parasite proteins. They act rapidly, killing blood stages of all Plasmodium species and reducing the parasite biomass. Artemisinins have the fastest parasite clearance times of any antimalarial. Artemisinins are active against gametocytes, the parasite form that is infectious to mosquitoes, and their use has been associated with reduced malaria transmission when they were introduced in Thailand.

To diagnose malaria, your doctor will likely review your medical history and recent travel, conduct a physical exam, and order blood tests. Blood tests can indicate:

The presence of the parasite in the blood, to confirm that you have malaria

Which type of malaria parasite is causing your symptoms

If your infection is caused by a parasite resistant to certain drugs

Whether the disease is causing any serious complications

Some blood tests can take several days to complete, while others can produce results in less than 15 minutes. Depending on your symptoms, your doctor may order additional diagnostic tests to assess possible complications. The most common antimalarial drugs include: Chloroquine phosphate. Chloroquine is the preferred treatment for any parasite that is sensitive to the drug. But in many parts of the world, parasites are resistant to chloroquine, and the drug is no longer an effective treatment. Artemisinin-based combination therapies (ACTs). ACT is a combination of two or more drugs that work against the malaria parasite in different ways. This is usually the preferred treatment for chloroquine-resistant malaria. Examples include artemether-lumefantrine (Coartem) and artesunate-mefloquine.Other common antimalarial drugs include:

Atovaquone-proguanil (Malarone)

Quinine sulfate (Qualaquin) with doxycycline (Oracea, Vibramycin, others)

Primaquine phosphate

Regards

Adina Bernice

Clinical and Experimental Pharmacology