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Antimalarial Drugs

A group of drugs that is used for the prevention and treatment of malaria

Common drugs

  • Artemether with lumefantrine

  • Chloroquine

  • Doxycycline

  • Mefloquine

  • Primaquine

  • Proguanil

  • Proguanil with atovaquone

  • Pyrimethamine with sulfadoxine

  • Quinine

Antimalarial drugs are prescribed as a preventive measure against infection with malaria and also as treatment if the disease develops. There are various types of antimalarial drug. Some are suitable only for treatment of the infection, while others are used for both prevention and treatment.

Malaria is a serious infectious disease caused by protozoa that are transmitted to humans by the bites of infected mosquitoes. The protozoa travel through the blood to the liver, where they multiply before re-entering the blood and circulating throughout the body. At this stage, the symptoms of malaria appear.

No antimalarial provides complete protection against the disease because malarial protozoa continually develop drug resistance. For this reason, you should protect yourself from mosquito bites if you visit an area where malaria occurs. It is important to keep your body well covered and to use insect repellents and netting (see Travel health).

How do they work?

Antimalarial drugs are effective at different stages in the life cycle of the malarial protozoa. When taken to prevent malaria, the drugs act by killing the protozoa when they enter the liver or the red blood cells. To treat malaria once symptoms have appeared, higher doses of drugs are given to destroy the protozoa when they are released from the liver into the blood. In some cases, the protozoa lie dormant in the liver and reactivate to cause recurrent episodes of malaria. These protozoa are difficult to eradicate and are treated with primaquine.

How are they used?

The choice of drug usually depends on the part of the world you plan to visit or where you contracted the disease.

If you plan to visit a malarial risk area, you need to start preventive treatment up to 3 weeks before departure, continuing for 1–4 weeks after your return (the exact timings depend on the drugs taken). Antimalarials are usually taken orally, either once a day or once a week. To increase protection against the most drug-resistant strains, combinations of drugs may be given. For example, proguanil may be taken with chloroquine.

If you develop malaria, the drugs used for treatment may be taken orally or given by injection up to several times a day for several days. If you have recurrent bouts of malaria, your doctor will prescribe an oral antimalarial such as primaquine for 2–3 weeks or more to eradicate the protozoa.

What are the side effects?

Antimalarial drugs can cause a number of side effects, including nausea, diarrhoea, headaches, rashes, and blood disorders. Quinine can cause ringing in the ears (see Tinnitus), blurred vision, and hot flushes. Mefloquine can cause some people to experience panic attacks, dizziness, hallucinations, and depression.

If you are, or think you might be, pregnant, you should consult your doctor or pharmacist before taking antimalarial drugs. Mefloquine and chloroquine should not be taken by people with epilepsy.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

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