Antiprotozoal

Antiprotozoal drugs are a class of medication used to treat infections caused by protozoa, which are single-cell organisms that belong to the type of parasites. Protozoal infections occur throughout the world and are a major cause of morbidity and mortality in some regions such as Africa and South-East Asia.

1. Memoona Arshad – Group 11 Antiprotozoal

2. Antiprotozoal Antiprotozoal agents is a class of pharmaceuticals used in treatment of protozoan infection. Protozoans have little in common with each other(for example, Entamoeba histolytica , a unikont eukaryotic organism, is more closely related to Homo sapiens, which belongs to the unikont phylogenetic group, than it is to Naegleria fowleri , a bikont eukaryotic organism) and so agents effective against one pathogen may not be effective against another. They can be grouped by mechanism or by organism.

3. Introduction The use of antiprotozoal drugs in dogs and cats is frequently extrapolated from their use in human patients or food animal species. Almost all antiprotozoal drugs are not specifically approved for treatment of protozoal infections in dogs and cats. Some antibacterial and antifungal drugs also have antiprotozoal activity. In vitro activity of antiprotozoal drugs, and monitoring of resistance, is more difficult for antiprotozoal drugs because standardized susceptibility testing is not routinely performed for these pathogens. In addition, many antiprotozoal drugs are designed to be active in the lumen of the intestine for treatment of intestinal protozoal infections and the concentration of active drug in the intestinal lumen after oral administration is difficult to measure. Therefore , the concentration of drug to which these pathogens are exposed is often not known. The activity and dosage regimens of antiprotozoal drugs are often based on the results of clinical trials, rather than concentration-exposure relationships between antiprotozoal drugs and the organism of interest.

4. Medical Uses Antiprotozoals are used to treat protozoal infections, which include Amebiasis giardiasis Cryptosporidiosis Microsporidiosis Malaria Babesiosis Trypanosomiasis Chagas disease Leishmaniasis toxoplasmosis Currently, many of the treatments for these infections are limited by their toxicity.

5. Metronidazole Metronidazole is usually given orally for the treatment of vaginal infections caused by  Trichomonas vaginalis , and it is effective in treating bacterial infections caused by anaerobes (organisms that can survive without oxygen ). It affects these organisms by causing nicks in, or breakage of, strands of DNA or by preventing DNA replication. Metronidazole is also the drug of choice in the treatment of giardiasis, an infection of the intestine caused by a flagellated amoeba.

6. Iodoquinol Iodoquinol inhibits several enzymes of protozoans . It is given orally for treating asymptomatic amoebiasis and is given either by itself or in combination with metronidazole for intestinal and hepatic amoebiasis .

7. Pneumocystis Pneumocystis carinii  causes pulmonary disease in immunocompromised patients. These infections are treated with trimethoprim-sulfamethoxazole , which inhibits folic acid synthesis in protozoans . An  alternative agent for treatment of these diseases is  pentamidine isethionate , which probably affects the parasite by binding to DNA.

8. Trypanosomes Trypanosomes are flagellated protozoans that cause a number of diseases. Trypanosoma cruzi , the causative agent of Chagas ’ disease, is treated with nifurtimox , a nitrofuran derivative. It is given orally and results in the production of activated forms of oxygen, which are lethal to the parasite. Other forms of trypanosomiasis (African trypanosomiasis, or sleeping sickness) are caused by T. brucei gambiense or T. brucei rhodesiense . When these parasites invade the blood or lymph , the drug of choice for either form is suramin, a nonmetallic  dye  that affects glucose utilization and hence energy production. Because suramin is not absorbed from the gastrointestinal tract, it is given by intravenous injection.

9. Chloroquine Chloroquine phosphate, given orally, is a drug used for the prevention and treatment of uncomplicated cases of malaria, which is caused by species of  Plasmodium. In regions where chloroquine -resistant P. falciparum  is encountered, mefloquine or doxycycline may be used for prevention of the disease. Infection with chloroquine -resistant P. falciparum  may be treated with quinine sulfate, often in combination with pyrimethamine and sulfadoxine , or with artemisinin, in combination with agents such as mefloquine or amodiaquine . A high level of quinine in the plasma frequently is associated with  cinchonism , a mild adverse reaction associated with such symptoms as a ringing noise in the ears (tinnitus), headache, nausea, abdominal pain, and visual disturbance.  Primaquine phosphate is given orally to prevent malaria after a person has left an area where P. vivax  and P. ovale  are endemic and to prevent relapses with the same organisms.

10. Outdated terminology Once upon a time protists were considered protozoans , but of late the categorization of unicellar organisms has undergone rapid development, however in literature, including scientific, there tends to persist the usage of the term antiprotozoal when they really mean  anti- protist . Protists are a supercategory of eukaryota which includes protozoa.

11. Mechanisms The mechanisms of antiprotozoal drugs differ significantly drug to drug. For example, it appears that eflornithine, a drug used to treat  trypanosomiasis, inhibits  ornithine decarboxylase , while the aminoglycoside  antibiotic/ antiprotozoals used to treat leishmaniasis are thought to inhibit protein synthesis.

12. References Antiprotozoal drug | Britannica Antiprotozoal Drugs- Medicinal Chemistry-Pharmacy (slideshare.net ) Definition of Antiprotozoal (medicinenet.com ) Antiprotozoal - Wikipedia

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