Antimalarials
Drugs that kill Plasmodium: artemisinin combinations for P. falciparum, chloroquine for P. vivax, primaquine against relapse, artesunate for severe malaria.
What they are
Drugs against the malaria parasites (Plasmodium falciparum, P. vivax, P. ovale, P. malariae, P. knowlesi). They are grouped by the parasite stage they hit: blood schizonticides clear the red-cell stages that cause the illness, tissue schizonticides (8-aminoquinolines) clear the dormant liver forms of P. vivax and P. ovale, and gametocytocides block transmission to mosquitoes. In Colombia P. vivax and P. falciparum cause almost all cases.
Mechanism of action
Several mechanisms. Quinolines (chloroquine, quinine, mefloquine, lumefantrine) block the parasite's detoxification of heme released when it digests haemoglobin, so toxic heme builds up. Artemisinins are activated by heme iron: their endoperoxide bridge opens and releases free radicals that damage parasite proteins. Atovaquone blocks the parasite's mitochondrial cytochrome bc1 complex; pyrimethamine and cycloguanil (from proguanil) inhibit parasite dihydrofolate reductase. 8-aminoquinolines (primaquine, tafenoquine) act on liver hypnozoites and gametocytes by a mechanism that is not fully known.
Target: Parasite heme detoxification, mitochondrial cytochrome bc1 and folate synthesis; artemisinins are activated by heme
Drugs in this class
- Artemether + lumefantrineThe artemisinin combination used in Colombia for uncomplicated P. falciparum malaria; taken with fatty food or milk so…Parasite heme (artemether is activated by heme iron; lumefantrine blocks heme detoxification)
- ArtesunateWater-soluble artemisinin given IV or IM as first treatment for severe malaria of any species; it clears parasites…Parasite heme iron, which opens the endoperoxide bridge (activation), and many parasite proteins
- ChloroquineOral 4-aminoquinoline for P. vivax, P. ovale and P. malariae; in Colombia it treats vivax malaria, with primaquine…Heme detoxification (hemozoin formation) in the parasite's digestive vacuole
- Primaquine8-aminoquinoline that kills dormant liver forms of P. vivax and P. ovale (radical cure) and blocks transmission; it…Not fully known: reactive metabolites act on liver hypnozoites and gametocytes
- QuinineCinchona alkaloid for malaria when ACTs cannot be used, mainly with clindamycin in early pregnancy; causes cinchonism…Heme detoxification in the parasite's digestive vacuole (presumed, like chloroquine)
- MefloquineLong-acting quinoline for malaria prevention in travellers and as a last-choice treatment; its boxed warning is…Not fully defined: binds hemozoin like chloroquine; one study showed it binding the P. falciparum 80S ribosome
- Atovaquone + proguanilDaily oral combination for malaria prevention in travellers and for uncomplicated P. falciparum; taken with food or…Parasite mitochondrial cytochrome bc1 complex, Qo site (atovaquone); parasite dihydrofolate reductase (cycloguanil, from proguanil)
- TafenoquineLong-acting 8-aminoquinoline, a single dose with chloroquine for P. vivax radical cure; G6PD must be shown normal first.Not fully known: like primaquine, acts on liver hypnozoites and gametocytes
- Dihydroartemisinin–piperaquineOral artemisinin combination for uncomplicated malaria: a fast, short-lived artemisinin plus piperaquine, which stays…Parasite heme (dihydroartemisinin is activated by heme iron; piperaquine blocks heme detoxification)
- Sulfadoxine–pyrimethamineFixed folate-blocking antimalarial combination, now used mostly to prevent malaria in pregnancy and in children in…Plasmodium dihydropteroate synthase (sulfadoxine) and dihydrofolate reductase (pyrimethamine)
Others in the class
- Artesunate + amodiaquine
- Artesunate + mefloquine
- Artesunate + pyronaridine
- Artesunate + sulfadoxine + pyrimethamine
- Dihydroartemisinin + piperaquine
- Sulfadoxine + pyrimethamine
- Artemether (injection)
- Hydroxychloroquine
Test yourself
Think of the answer, then tap the question to see it.
Which antimalarials act on the dormant liver forms (hypnozoites) of P. vivax?
The 8-aminoquinolines: primaquine and tafenoquine. Chloroquine and ACTs only clear blood stages, so without them P. vivax can relapse.
What is the first treatment for severe malaria?
Parenteral (intravenous or intramuscular) artesunate, followed by a full oral course of an artemisinin-based combination.
Why is an artemisinin always given with a partner drug?
Artemisinins clear parasites fast but are eliminated within hours; a longer-acting partner kills the survivors and protects both drugs from resistance.
Which test is checked before a full primaquine course?
G6PD activity, because primaquine can cause haemolytic anaemia in people with G6PD deficiency.
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Malaria (World Health Organization, 2025); Adopción Parcial de Guía de Práctica Clínica Diagnóstico y tratamiento de la malaria, OMS 2022. Guía para Colombia, GPC #67-2022 (Ministerio de Salud y Protección Social (Colombia), 2022); Treatment of Uncomplicated Malaria (Centers for Disease Control and Prevention (CDC), 2026).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.