Antiprotozoals and Antimalarial Drugs

An antiprotozoal drug used to treat infections caused by anaerobic bacteria and some protozoa.

Drugs that target protozoa, single-celled organisms that can cause infections.

An infection caused by the protozoan Giardia lamblia, often causing diarrhea.

An infection caused by the protozoan Entamoeba histolytica, often affecting the intestines.

A sexually transmitted infection caused by the protozoan Trichomonas vaginalis.

An antimetabolite used to treat toxoplasmosis, targeted against a specific enzyme.

A group of antiprotozoal drugs, some of which are commonly used to treat bacterial infections.

The growing stage of protozoa, sometimes used in drug mechanisms.

An organism that can produce its own food from inorganic substances.

Protozoa that live and infect the intestines.

Infection by amebae, specifically in the lumen, the inner space of the intestines; not invasive.

An animal that carries a disease-causing microorganism from one host to another.

Having a weakened immune system, making them more vulnerable to infections.

A vector-borne parasitic disease transmitted by Anopheles mosquitoes.

A vector-borne parasitic disease transmitted by ticks.

A type of fungus that can cause pneumonia, particularly in immunocompromised individuals.

The most dangerous species of Plasmodium, responsible for the most severe form of malaria.

A breakdown product of hemoglobin, toxic to parasitic protozoa.

A crystalline form of heme, produced by parasitic protozoa to neutralize its toxicity.

A parasitic stage where the parasite multiplies within a host cell, releasing numerous merozoites.

A stage of the parasitic protozoa that is released from a schizont and invades new host cells.

A dormant stage of the parasite, located in the liver, responsible for relapses in malaria.

They prevent the parasitic protozoa from crystallizing heme into hemozoin, causing the parasite to build up toxic heme levels and die.

Chloroquine interferes with the parasite's ability to digest hemoglobin by accumulating within food vacuoles, disrupting its metabolism.

Chloroquine is primarily used to treat malaria, a mosquito-borne parasitic disease.

Common side effects include nausea, vomiting, abdominal pain, and headache. Less common but serious effects include retinopathy (eye damage), seizures, and psychosis.

Hydroxychloroquine is another antimalarial drug with similar mechanisms and side effects to chloroquine, but it is more commonly used for systemic lupus erythematosus (lupus).

Do not take halofantrine with food. It should be taken on an empty stomach.

Cation-containing antacids reduce the absorption of quinine and chloroquine.

Amodiaquine can cause agranulocytosis (low white blood cell count) and liver toxicity with prolonged use.

Chloroquine can cause retinopathy (eye damage) with long-term use, mainly affecting the retina.

Artemisinin-based Combination Therapies (ACTs) are the primary treatment for uncomplicated malaria. This approach combines artemisinin with another antimalarial drug to prevent drug resistance.

For severe malaria, intravenous quinine is the preferred treatment. Mefloquine may be used as an alternative, but it's not the first choice.

Mefloquine has a unique mechanism of action that often leads to resistance when used alone. This is why it's not the first-line treatment.

Mefloquine's secondary mechanism of action involves blocking acetylcholinesterase. This enzyme is important in the nervous system, and its inhibition can lead to side effects.

To eliminate dormant liver hypnozoites (sleeping parasites), primaquine is used. It's not recommended for pregnant women.

Cinchonism is a collection of side effects associated with quinine. These effects include ringing in the ears (tinnitus), headache, nausea, abdominal pain, and blurred vision.

For pregnant women, chloroquine is the first-line prophylactic drug. Primaquine is given after childbirth.

First-line treatment for babesiosis usually involves azithromycin and atovaquone. Quinine and clindamycin can be used as alternatives.

The malaria parasite undergoes a complex life cycle involving two hosts: humans and mosquitos. It begins with a mosquito bite, the parasite enters the human bloodstream, infects liver cells, and then invades red blood cells, where it multiplies and causes symptoms. The parasite then transforms into gametes in the red blood cells, which are ingested by a mosquito during a blood meal. Sexual reproduction occurs inside the mosquito, and sporozoites are formed. These sporozoites travel to the mosquito's salivary glands, thus completing the cycle.

Malaria parasites digest hemoglobin from red blood cells, releasing toxic heme. To survive, they convert this heme into a non-toxic crystalline form called hemozoin. This process is vital for the parasite's survival.

Chloroquine is an antimalarial drug that works by interfering with hemozoin crystallization inside the parasite. This prevents the parasite from detoxifying heme, leading to the parasite's death.

Malaria parasites can develop resistance to antimalarial drugs like chloroquine. This resistance often arises from mutations in the parasite's transporter protein, which is involved in transporting molecules into the digestive vacuole where hemozoin formation occurs.

Artemisinin is a powerful antimalarial drug derived from the plant Artemisia annua. Artemisinin derivatives have an endoperoxide bridge, which is crucial for their action. They are most effective against rapidly multiplying parasites.

Prophylaxis refers to measures taken to prevent malaria infection. It involves using antimalarial drugs (like mefloquine) prior to travel to malaria-endemic areas, as well as preventative measures like mosquito bite prevention.

Treatment for malaria usually involves a combination of drugs. Quinolones are used for treatment, but resistance is emerging. Chloroquine is no longer recommended as monotherapy due to increasing resistance. Artemisinin derivatives, combined with other drugs, are commonly used.

Preventing malaria transmission involves controlling mosquito populations. This can be achieved through measures such as removing stagnant water sources where mosquitoes breed, using insect repellents, and avoiding outdoor exposure during peak mosquito activity hours.