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Antiprotozoal Drugs- Medicinal Chemistry-Pharmacy

This document discusses anti-protozoal drugs used to treat protozoan infections. It describes how protozoan infections are caused by organisms formerly classified as protozoa and are contracted through insect vectors or contact with infected substances. It then outlines several classes of pharmaceuticals used to treat protozoan diseases, including nitroimidazole derivatives like metronidazole, diloxanide, iodoquinol, pentamidine, atovaquone, and eflornithine. It provides details on the structures and mechanisms of action of these various antiprotozoal agents.

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Anti Protozoal Drugs Dr. Akhil Nagar RCP-IPER Shirpur
Anti Protozoal Drugs • Protozoan infections are parasitic diseases caused by organisms formerly classified in the Kingdom Protozoa. • They are usually contracted by either an insect vector or by contact with an infected substance or surface and include organisms called Amoebozoa. • Protozoan infections are responsible for diseases that affect many different types of organisms. Many of the most prevalent and deadly human diseases are caused by a protozoan infection, including African Sleeping Sickness, amoebic dysentery, and malaria.
• The species originally termed "protozoa" are not closely related to each other and only have superficial similarities. • In some areas with temperate climates in which sanitation is poor, the prevalence of amebiasis has been estimated to be as high as 20% of the population. • The causative organism, Entamoeba histolytica, can invade the wall of the colon or other parts of the body. • Antiprotozoal agents is a class of pharmaceuticals used in treatment of protozoan infection. • Common protozas are Trypanosoma which is a genus of kinetoplastids. • African trypanosomiasis, also known as African sleeping sickness or simply sleeping sickness, is an insect- borne parasitic disease.
• The Amebicides that are effective against both intestinal and extraintestinal forms of the disease. • Group-1: Alkaloids emetine and dehydroemetine, the nitroimidazole derivative metronidazole, and the antimalarial agent chloroquine and Atovaquone • Group-2: amebicides that are effective only against intestinal forms of the disease includes the aminoglycoside antibiotic paromomycin, 8- hydroxyquinoline derivative iodoquinol and diloxanide. • Other than Trypanosoma, Leishmaniasis is a chronic tropical disease caused by various flagellate protozoa of the genus Leishmania. • The more common visceral form caused by Leishmania donovani, called kala-azar.
Metronidazole Tinidazole, Ornidazole 2-Methyl-5-nitroimidazole-1-ethanol
• Nitoimidazole Derivatives: • It is effective against Gram-positive anaerobic bacilli. It is also effective against Gram-positive anaerobic bacilli, bactericidal in action. • Reactive intermediate formed in the microbial reduction of the 5-nitro group of metronidazole covalently binds to the DNA of the microorganism • Potential reactive intermediates include the nitroxide, nitroso, hydroxylamine, and amine. • Metronidazole acts as an artificial electron acceptor after accumulating with in cell as reduced comp. • Nitro group accepts the proton and divert the normal pathway. • The electron sources can be NADH or sulfide bonds. • Metronidazole and other derivatives can also cause loss of helical structure of DNA.
Diloxanide Iodoquinol Pentamidine
• DILOXANIDE: • Its an ester of 2,2-dichloro methylacetanilide, with the discovery of dichloroacetamides which possessed amebicidal activity. • Drug metabolism studies indicate that hydrolysis of the amide is required for the amebicidal effect. • Nonpolar esters of diloxanide are more potent than polar ones. • IODOQUINOL: • 5,7-Diiodo-8-quinolinol microcrystalline, light-sensitive substance.
• Pentamidine Isethionate: • The principal use of pentamidine is for the treatment of pneumonia. • Pentamidine has been used for the prophylaxis and treatment of African trypanosomiasis. It also has some value for treating visceral leishmaniasis. • Atovaquone: 1,4-naphthoquinone, highly lipophilic, water-insoluble, an essential component of the mitochondrial electron transport chain in microorganisms. • They interfere with the function of electron transport enzymes. • Eflornithine: • Eflornithine is a myelosuppressive drug that causes high incidences of anemia, leukopenia, and thrombocytopenia.
• The irreversible inactivation of ornithine decarboxylase by eflornithine is accompanied by decarboxylation and release of fluoride ion from the inhibitor. • Eflornithine is supplied as the hydrochloride salt. It may be administered either intravenously or orally. Approximately 80% of the unchanged drug is excreted in the urine. Isethionates are esters of long-chain aliphatic carboxylic acids (C8 – C18) with isethionic acid (2-hydroxyethanesulfonic acid) or salts thereof, such as ammonium isethionate or sodium isethionate. They are also referred to as acyl isethionates or acyloxyethanesulfonates.
Atovaquone Eflornithine