How Do Antimalarials Work?

Reviewed on 9/28/2021

HOW DO ANTIMALARIALS WORK?

  • Antimalarial drugs are used to treat malaria and as a prophylaxis for malaria. Antimalarial drugs are also used to treat other diseases such as Pneumocystis carinii pneumonia, rheumatoid arthritis, systemic lupus erythematosus, and arrhythmias (irregular heartbeats).
  • Antimalarial drugs work by killing the parasite present in the affected red blood cells. There are several antimalarial drugs that differ in their structure with each working uniquely to kill the parasite.
  • Artemether/lumefantrine: Inhibits nucleic acid and protein synthesis and the parasite through endoperoxide or possibly by inhibiting beta-hematin formation.
  • Artesunate: Contains endoperoxide bridge activated by heme iron and leads to oxidative stress; it inhibits protein and nucleic acid synthesis and ultrastructural changes and reduces parasite growth and survival.
  • Atovaquone: Inhibits the electron transport chain at cytochrome bc1 complex and collapses parasite mitochondrial membrane in Plasmodium
  • Atovaquone/proguanil: Disrupts electron transport and collapses the mitochondria, whereas proguanil inhibits enzyme dihydrofolate reductase essential for reproduction of the parasite. 
  • Chloroquine: Acts against erythrocytic forms of Plasmodium; however, the exact mechanism of action is unknown.
  • Hydroxychloroquine sulfate: Exact action against Plasmodium is unknown. As it is a weak base, it may affect acid vesicles of the parasite and inhibit polymerization of heme. It may also inhibit other essential enzymes.
  • Mefloquine: Structural analog of quinine; although its exact mechanism is unknown, it kills schizonts in the blood. This may increase intravesicular pH in parasites.
  • Primaquine: Disrupts Plasmodium mitochondria, leading to the death of the parasite.
  • Pyrimethamine: Folic acid antagonist, selectively inhibiting plasmodial form of dihydrofolate reductase enzyme and reducing the production of folic acid required for nucleic acid synthesis in the parasite.
  • Quinidine: Builds up in the food vacuole of the parasite and forms a complex with heme and starves the Plasmodium to death.
  • Quinine: Although the mechanism of action of this drug is unknown; quinine may disrupt Plasmodium DNA transcription/replication and interferes with the digestion of hemoglobin. This leads to starvation and death of the parasite.
  • Tafenoquine: The metabolite of tafenoquine is active against pre-erythrocytic form in the liver and erythrocytic form in the blood and gametocytes of Plasmodium and prevents its development, thus preventing relapse of malaria.

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HOW ARE ANTIMALARIALS USED?

Antimalarials are given as injections, oral tablets, or oral suspension to treat:

  • Malaria
    • Uncomplicated malaria (Plasmodium falciparum)
    • Chloroquine-resistant (Plasmodium falciparum, Plasmodium vivax)
  • Malaria (prophylaxis)
  • Prevention of relapse of Plasmodium vivax malaria
  • Acute malarial infection

Antimalarials are also used in conditions such as:

WHAT ARE SIDE EFFECTS OF ANTIMALARIALS? 

Side effects associated with antimalarials include:

 

The information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

WHAT ARE NAMES OF ANTIMALARIALS?

Generic and brand names of antimalarials include:

QUESTION

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References
https://reference.medscape.com/drugs/antimalarials

https://malariajournal.biomedcentral.com/articles/10.1186/1475-2875-7-S1-S8

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