Antiparasitics

Antiparasitic drugs are medications used to treat infections caused by parasites. Parasites are organisms that live on or inside the human body and rely on it for survival. These infections are more common in certain parts of the world, but can affect people anywhere through contaminated food or water, insect bites, or close contact.

Antiparasitic drugs play an essential role in infectious disease treatment. They are used to treat a wide range of parasitic diseases, from mild intestinal infections to serious, life-threatening illnesses such as malaria and river blindness. Because parasites vary widely in structure and behavior, different antiparasitic agents are used depending on the type of organism involved.

Antiparasitic drugs, also called antiparasitic agents, are medications designed to kill parasites or stop them from growing and reproducing. They are considered a type of antimicrobial medication, but they work differently from antibiotics, which target bacteria.

Parasitic infections are broadly divided into those caused by protozoa, helminths, and ectoparasites. Protozoa are single-celled organisms such as Giardia or Plasmodium. Helminths are parasitic worms, including roundworms, hookworms, and tapeworms. Ectoparasites live on the surface of the body and include organisms that cause scabies.

Antiparasitic drugs are selected based on the specific parasite, the location of infection, and the severity of disease.

Antiparasitic drugs work through different mechanisms of action depending on the parasite they target. Some drugs interfere with the parasite’s nervous system, while others disrupt energy production, cell membranes, or reproduction.

Certain anthelmintic and antihelminthic drugs affect chloride channels or muscle function in helminths, causing paralysis and death of the worms. Others interfere with the parasite’s ability to absorb nutrients.

Antiprotozoal drugs often target DNA synthesis, metabolic enzymes, or other essential processes inside protozoa. Antimalarial drugs interfere with parasite survival inside red blood cells. These varied mechanisms allow antiparasitic drugs to be effective against a wide range of parasitic diseases.

Drugs for helminths (worms)

These medications are used to treat helminth infections caused by nematodes, roundworms, tapeworms, and related parasites.

Albendazole (Albenza).

Mebendazole (Vermox).

Ivermectin (Stromectol), also used for scabies and other ectoparasitic infections.

Praziquantel (Biltricide).

Pyrantel pamoate (Pin-X, Reese’s Pinworm Medicine).

Diethylcarbamazine (Hetrazan).

Levamisole (Ergasimol, Ascardil).

These drugs are commonly used for ascariasis, enterobiasis (pinworm), hookworm, strongyloidiasis, tapeworm infections, and river blindness.

Antiprotozoal drugs

These broad-spectrum medications target protozoa that cause intestinal and systemic infections.

Metronidazole (Flagyl).

Tinidazole (Tindamax).

Nitazoxanide (Alinia).

Paromomycin (Humatin).

Iodoquinol (Yodoxin).

Pentamidine (Pentam 300).

Benznidazole (Rochagan).

Eflornithine (Ornidyl).

They are used for giardiasis, trichomoniasis, toxoplasmosis, amoebic infections, and trypanosomiasis.

Antimalarial drugs

Antimalarial drugs are used to treat infections caused by Plasmodium species.

Chloroquine (Aralen).

Quinine (Qualaquin).

Artemether/ Lumefantrine(Coartem).

These medications are often used in combination and are essential for treating malaria, a serious parasitic disease transmitted by mosquitoes.

Drugs for leishmaniasis

Sodium stibogluconate (Pentostam).

Meglumine antimoniate (Glucantime).

Miltefosine (Impavido).

These are used to treat cutaneous leishmaniasis and other forms of leishmanial infection.

Antiparasitic drugs are used to treat a wide range of parasitic infections.

Intestinal and gastrointestinal infections: to treat intestinal infection caused by protozoa or worms. This includes giardiasis, ascariasis, pinworm, and hookworm infections.

Systemic parasitic diseases: for malaria, toxoplasmosis, trypanosomiasis, and parasitic diseases that affect the blood or nervous system.

Skin and ectoparasitic infections: to treat infections that affect the skin, such as scabies and cutaneous leishmaniasis.

Prevention and public health: to reduce the spread of parasitic diseases in high-risk populations.

Common side effects include:

• Nausea or vomiting.

• Abdominal pain or diarrhea.

• Headache or dizziness.

Some antiparasitic drugs can cause more serious side effects, including liver toxicity, nervous system effects, or allergic reactions. Ivermectin and praziquantel may cause symptoms related to parasite die-off, such as fever or rash.

These are not all of the possible side effects of antiparasitics. You should always seek medical advice from your healthcare provider for any questions or concerns about your medical condition or treatment. Read all patient information, medication guides, or drug information sheets that come with this medication. You can also report adverse effects to the Food and Drug Administration at www.fda.gov/medwatch or 1-800-FDA-1088.

Although these medications are generally well-tolerated and safe, there are certain warnings, precautions, and drug interactions you should be aware of.

Warnings

Before starting antiparasitics, it is crucial to discuss any existing health conditions with your healthcare provider. You should be sure that your healthcare provider is aware of all your medical conditions, including:

Liver disease.

Kidney disease.

Neurologic conditions.

A weakened immune system.

Contraindications

Antiprotozoal agents

Chloroquine should not be used if you:

Are allergic to 4-aminoquinoline drugs.

Have G6PD deficiency.

Have porphyria or psoriasis.

Have vision problems or muscle disease.

Primaquine should not be used if you:

Have G6PD deficiency.

Have certain blood disorders, including methemoglobinemia or low white blood cells.

Are pregnant.

Mefloquine should not be used if you:

Have heart rhythm or conduction problems.

Have epilepsy or seizure disorders.

Have psychiatric or mental health conditions.

Need to perform tasks that require high alertness or fine motor skills.

Iodoquinol should not be used if you:

Have kidney disease.

Have thyroid disease.

Are sensitive to iodine.

Have ongoing iodine toxicity symptoms such as fever, itching, or skin irritation.

Diloxanide furoate should generally be avoided if you:

Are pregnant.

Metronidazole should not be used if you:

Are pregnant.

Drink alcohol while taking it, due to a severe reaction.

Take lithium or blood thinners like warfarin without close monitoring.

Emetine should not be used if you:

Have kidney disease.

Have heart disease.

Are pregnant.

Antihelminthic agents

Albendazole should not be used if you:

Have liver cirrhosis.

Are allergic to benzimidazole medications.

Amphotericin B should be used with caution if you:

Have kidney problems.

Take other medications that can damage the kidneys.

Praziquantel should not be used if you:

Have eye involvement from parasitic infection.

Need to stay alert for activities such as driving.

Are pregnant.

Ectoparasiticides

Lindane should not be used if you:

Have a seizure disorder.

Are an older adult, a young child, or weigh less than 50 kg, unless no other options are available.

Drug interactions

When antiparasitics are taken with other prescription drugs, over-the-counter medications, vitamins, and supplements, it may change how they work or increase the frequency or severity of side effects. Make sure that you tell your healthcare professional about anything that you are taking to avoid any negative drug interactions.

Drug interactions depend on the specific antiparasitic, but can include:

Ivermectin interacts with blood thinners, CNS depressants, azole antifungals, and alcohol.

Drugs that impact the action of certain liver enzymes.