How Do Aminoquinoline Antimalarials Work?

Aminoquinoline antimalarials are drugs used to treat and prevent malaria. They act against all malarial parasites, especially Plasmodium malariae, Plasmodium vivax, and all strains of Plasmodium falciparum.

Aminoquinoline antimalarials include:

Chloroquine: Inhibits the activity of an enzyme heme polymerase in malarial trophozoites; this prevents the conversion of heme to hemozoin. This leads to the accumulation of poisonous heme, eventually killing the parasite. Chloroquine accumulates in the organelles such as lysosomes and endosomes, increases the pH of the parasite, and alters the process of protein degeneration which changes their functionality and thus cannot enter into the host cells.

Hydroxychloroquine sulfate, whose exact mechanism of action is unknown, increases pH in the parasite and interferes with an enzyme that prevents normal growth and replication of the parasite. Hydroxychloroquine sulfate also increases the concentrations of toxic heme.

Primaquine may bind with and alter the properties of parasite DNA. 

Tafenoquine is active against most forms of Plasmodium in the body. Tafenoquine has good activity against hypnozoite, the pre-erythrocytic stage, which grows in the liver. The prevention of hypnozoite can prevent relapse of Plasmodium vivax malaria.

Aminoquinoline antimalarials are indicated for:

• Treatment of uncomplicated malaria due to Plasmodium falciparum, Plasmodium malariae, Plasmodium ovale, and Plasmodium vivax
• Prophylaxis of malaria in geographic areas where chloroquine resistance is not reported

Other uses of aminoquinoline antimalarials include:

• Systemic lupus erythematosus (an inflammatory disease caused when the immune system attacks its own tissues)
• Rheumatoid arthritis (an autoimmune and inflammatory disorder affecting many joints, including those in the hands and feet)

Off-label use includes:

• Coronavirus Disease (COVID-19)
• Porphyria Cutanea Tarda (a rare disorder characterized by painful, blistering skin lesions that develop on sun-exposed skin [photosensitivity])

Side effects associated with aminoquinoline antimalarials include:

• Headache
• Nausea and vomiting
• Dizziness
• Somnolence (state of being drowsy)
• Motion sickness
• Sleeplessness 
• Hypotension (low blood pressure)
• Hypoglycemia (low blood sugar)
• Ventricular arrhythmias (irregular heartbeats in the lower chambers of the heart)
• Atrioventricular block (heart block caused by impairment of electrical impulses traveling from atria to other chambers of the heart)
• Abdominal pain
• Anorexia (an eating disorder where there is loss of appetite)
• Hepatitis (inflammation of the liver)
• Increased liver enzymes
• Jaundice (yellowing of skin and eyes)
• Cytopenia (decrease in different types of blood cells) 
• Myopathy (disease of skeletal muscle that affects the movement of the body)
• Blurred vision
• Eye changes that affect vision
• Photophobia (inflammation of the skin when exposed to ultraviolet rays)
• Tinnitus (ringing in the ears)
• Hair loss
• Hypoesthesia (complete or partial loss of sensation in the body)
• Syncope (fainting or a sudden temporary loss of consciousness)
• Tremors
• Confusion
• Mood disorder
• Suicidal ideation
• Anaphylactic reaction (life-threatening allergic reactions)

 

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.

Generic and brand names of aminoquinoline antimalarials include:

• Arakoda
• Chloroquine
• Chloroquine phosphate
• Hydroxychloroquine sulfate
• Krintafel
• Plaquenil
• Primaquine
• Tafenoquine