Antiparasitics are a class of

medications A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the medical field and re ...

which are indicated for the treatment of parasitic diseases, such as those caused by

helminths Parasitic worms, also known as helminths, are large macroparasites; adults can generally be seen with the naked eye. Many are intestinal worms that are soil-transmitted and infect the gastrointestinal tract. Other parasitic worms such as ...

amoeba An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudop ...

, ectoparasites, parasitic fungi, and

protozoa Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Histo ...

, among others. Antiparasitics target the parasitic agents of the infections by destroying them or inhibiting their growth; they are usually effective against a limited number of parasites within a particular class. Antiparasitics are one of the

antimicrobial An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ar ...

drug A drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via inhala ...

s which include

antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and preventio ...

that target

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

, and

antifungal An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as ...

s that target

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately fr ...

. They may be administered orally, intravenously or topically. Broad-Spectrum antiparasitics, analogous to

broad-spectrum antibiotic A broad-spectrum antibiotic is an antibiotic that acts on the two major bacterial groups, Gram-positive and Gram-negative, or any antibiotic that acts against a wide range of disease-causing bacteria. These medications are used when a bacterial ...

s for bacteria, are antiparasitic drugs with efficacy in treating a wide range of parasitic infections caused by parasites from different classes.

Types

Broad-spectrum

Nitazoxanide Nitazoxanide, sold under the brand name Alinia among others, is a broad-spectrum antiparasitic and broad-spectrum antiviral medication that is used in medicine for the treatment of various helminthic, protozoal, and viral infections. It is ind ...

Antiprotozoals

* Melarsoprol (for treatment of sleeping sickness caused by ''

Trypanosoma brucei ''Trypanosoma brucei'' is a species of parasitic kinetoplastid belonging to the genus '' Trypanosoma'' that is present in sub-Saharan Africa. Unlike other protozoan parasites that normally infect blood and tissue cells, it is exclusively extrace ...

'') * Eflornithine (for sleeping sickness) *

Metronidazole Metronidazole, sold under the brand name Flagyl among others, is an antibiotic and antiprotozoal medication. It is used either alone or with other antibiotics to treat pelvic inflammatory disease, endocarditis, and bacterial vaginosis. It is ...

(for

vaginitis Vaginitis, also known as vulvovaginitis, is inflammation of the vagina and vulva. Symptoms may include itching, burning, pain, discharge, and a bad smell. Certain types of vaginitis may result in complications during pregnancy. The three ma ...

caused by

Trichomonas ''Trichomonas'' is a genus of anaerobic excavate parasites of vertebrates. It was first discovered by Alfred François Donné in 1836 when he found these parasites in the pus of a patient suffering from vaginitis, an inflammation of the vagina ...

) *

Tinidazole Tinidazole is a drug used against protozoan infections. It is widely known throughout Europe and the developing world as a treatment for a variety of anaerobic amoebic and bacterial infections. It was developed in 1972 and is a prominent member o ...

(for intestinal infections caused by '' Giardia lamblia'') *

Miltefosine Miltefosine, sold under the trade name Impavido among others, is a medication mainly used to treat leishmaniasis and free-living amoeba infections such as ''Naegleria fowleri'' and ''Balamuthia mandrillaris''. This includes the three forms of le ...

(for the treatment of visceral and cutaneous

leishmaniasis Leishmaniasis is a wide array of clinical manifestations caused by parasites of the trypanosome genus '' Leishmania''. It is generally spread through the bite of phlebotomine sandflies, ''Phlebotomus'' and ''Lutzomyia'', and occurs most freq ...

, currently undergoing investigation for

Chagas disease Chagas disease, also known as American trypanosomiasis, is a tropical parasitic disease caused by ''Trypanosoma cruzi''. It is spread mostly by insects in the subfamily '' Triatominae'', known as "kissing bugs". The symptoms change over the co ...

)

Antihelminthic

Antinematodes

* Mebendazole (for most nematode infections) *

Pyrantel pamoate Pyrantel is a medication used to treat a number of parasitic worm infections. This includes ascariasis, hookworm infections, enterobiasis (pinworm infection), trichostrongyliasis, and trichinellosis. It is taken by mouth. Side effects inclu ...

(for most nematode infections) * Thiabendazole (for roundworm infections) *

Diethylcarbamazine Diethylcarbamazine is a medication used in the treatment of filariasis including lymphatic filariasis, tropical pulmonary eosinophilia, and loiasis. It may also be used for prevention of loiasis in those at high risk. While it has been used for ...

(for treatment of Lymphatic filariasis) * Ivermectin (for prevention of river blindness)

Anticestodes

Niclosamide Niclosamide, sold under the brand name Niclocide among others, is an anthelmintic medication used to treat tapeworm infestations, including diphyllobothriasis, hymenolepiasis, and taeniasis. It is not effective against other worms such as flukes ...

(for

tapeworm Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda (the other subclass is Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Cesto ...

infections) * Praziquantel (for tapeworm infections) * Albendazole (broad spectrum)

Antitrematodes

* Praziquantel

Antiamoebics

* Rifampin *

Amphotericin B Amphotericin B is an antifungal medication used for serious fungal infections and leishmaniasis. The fungal infections it is used to treat include mucormycosis, aspergillosis, blastomycosis, candidiasis, coccidioidomycosis, and cryptococcosis ...

Antifungals

Fumagillin Fumagillin is a complex biomolecule and used as an antimicrobial agent. It was isolated in 1949 from the microbial organism ''Aspergillus fumigatus''. Uses In animals It was originally used against microsporidian parasites '' Nosema apis'' infect ...

(for microsporidiosis)

Medical uses

Antiparasitics treat parasitic diseases, which impact an estimated 2 billion people.

Administration

Antiparastics may be given via a variety of routes depending on the specific medication, including oral, topical, and intravenous. Resistance to antiparasitics has been a growing concern, especially in veterinary medicine. The

Egg hatch assay Egg hatch assay (EHA), also called an egg hatch test (EHT), is a method used to determine a given parasite's resistance to extant drug therapy Pharmacotherapy is therapy using pharmaceutical drugs, as distinguished from therapy using surgery (su ...

can be used to determine whether a parasite causing an infection has become resistant to standard drug treatments.

Drug development history

Early antiparasitics were ineffective, frequently toxic to patients, and difficult to administer due to the difficulty in distinguishing between the host and the parasite. Between 1975 and 1999 only 13 of 1,300 new drugs were antiparasitics, which raised concerns that insufficient incentives existed to drive development of new treatments for diseases that disproportionately target low-income countries. This led to new public sector and public-private partnerships (PPPs), including investment by the

Bill and Melinda Gates Foundation The Bill & Melinda Gates Foundation (BMGF), a merging of the William H. Gates Foundation and the Gates Learning Foundation, is an American private foundation founded by Bill Gates and Melinda French Gates. Based in Seattle, Washington, it was l ...

. Between 2000 and 2005, twenty new antiparasitic agents were developed or in development. Metal-containing compounds are the subject of another avenue of approach.

Research

In the last decades, triazolopyrimidines and their metal complexes have been looked at as an alternative drug to the existing commercial antimonials, searching for a decrease in side effects and the development of parasite drug resistance.

References

{{Authority control Biocides