Amoebiasis

Salts of acetarsone are used in the treatment of intestinal amoebiasis, vaginal trichomoniasis, and necrotizing ulcerative gingivitis (Vincent s angina). The diethylamine salt (acetylarsan [534-33-8]) has antisyphilitic properties. Because of toxicity problems, safer dmgs have been developed. Oral LD q in rabbits is 150 mg /kg. 

E. histolytica colonization of the large intestine is eradicated using a luminal agent such as diloxanid furoate or paromomycin. Invasive amoebiasis (colitis,... 

Entamoeba histolytica is an anaerobic rhizopod that occurs in tropical and subtropical areas. It can cause intestinal and extraintestinal manifestations. It is transmitted orally by ingestion of cysts that develop into trophozoites in the large intestine. Amebic trophozoites release several cytolytic factors, e.g. amoe-bapore, which enable the parasite to invade tissue. In intestinal amoebiasis, E. histolyticatrophozoites invade the intestinal mucosa, causing a form of ulcerative colitis with bloody and mucous diarrhoea. Extraintestinal manifestation of amebiasis results in abscess formation, usually in the liver but sometimes in the brain. 

Paromomycin finds special use in the treatment of intestinal amoebiasis (it is amoebicidal against histolytica) and of acute bacillary dysentery. 

The emetic principle of ipecacuanha, emetine (363), has found important application against amoebiasis. An aqueous solution of the dihydrochloride was irradiated to ca. 50% decomposition at 254 nm. The decomposition pattern was qualitatively similar at longer wavelength (300 or 350 nm), but the reaction rate was reduced. The products isolated and characterized in an impressive piece of work included emetamine (l, 2, 3, 4 -tetradehydro-emetine), O-methylpsychotrine (l, 12-didehydroemetine), 1, 2 -didehydro-emetine and the dihydroisoquinolines (364) and (365). There were also five quaternary ammonium derivatives (366) to (370) isolated as their hydroxides [210]. 

VI.a.1. Agents Against Amoebiasis and Other Protozoal Diseases... 

Metronidazole is a nitro-imidazole. It is a mixed amoebicide, i.e. it acts at all sites of infection. It has to be activated in the parasite. By reduction in the amoeba of its nitro group reactive intermediates are formed, resulting in oxidative damage and ultimately cell kill. It is effective against many parasitic intestinal and tissue infections such as trichomoniasis, giardiasis and amoebiasis. It is the drug of choice for amoebic dysentery and amoebic liver abscess. 

Of the dichloroacetamides diloxanide furoate, clefamide, teclozan and etofamide the most frequently used agent is diloxanide furoate. It is the luminal amoebicide of choice in chronic intestinal amoebiasis, however it lacks efficacy acute intestinal amoebiasis. Its mechanism of action is unknown. Given orally, diloxanide is formed by bacterial hydrolases. Diloxanide is for 90% absorbed and then metabolized to diloxanide glucuronide. The remaining 10% remains in the intestine as the active drug. Diloxanide is generally well tolerated. Adverse effects include flatulence, nausea and abdominal cramps. 

The diagnosis is made by appropriate combinations of colonoscopy, biopsy and contrast radiology. Disease has to be differentiated from ulcerative colitis (see above) and from infective disease, notably tuberculosis and amoebiasis as well as diverticular disease and cancer. 

ZO105 Sohni, Y. R., and R. M. Bhatt. Activity of a crude extract formulation in experimental hepatic amoebiasis and in immunomodulation studies. J Ethnopharmacol 1996 54(2/3) 119-124. 

Diloxanide furoate is the furoate ester of 2,3-dichloro-4-hydroxy-A-methyl acetanilide. This antiamoebic drug was developed as a result of the discovery that various a,a-dichloroacetamides possessed an amoebicidal activity [1]. Diloxanide furoate is considered as a safe and effective drug for the treatment of asymptotic or mildly symptomatic persons who are passing cysts of Entameba histolytica [2,3], It acts principally in the bowel lumen, and is used in the treatment of the intestinal amoebiasis. It is less effective in amebic dysentery than in asymptotic infection, but the furoate gives high intestinal concentrations and is possibly more effective than metronidazole in the treatment of cyst passers [4],... 

Amoebiasis is an infectious disease caused by Entamoeba histolytica. It can cause asymptomatic intestinal infection, colitis (mild to moderate), dysentery (severe intestinal infection), ameboma, liver abscess etc. The drugs used in chemotherapy of amoebiasis are classified as in table 9.9.1. 

It is indicated in giardiasis, amoebic liver abscess, intestinal amoebiasis, trichomoniasis, ulcerative gingivitis, treatment and prophylaxis of anaerobic infections. 

It is also used in combination with diloxanide furoate and dicyclomine to eradicate intestinal and extraintestinal amoebiasis and also asymptomatic cyst passers. 

Diiodohydroxyquinoline is directly amoebicidal. It has activity against motile and cystic forms. It kills cyst forming trophozoites in intestine but has no tissue amoebicidal action. It is ineffective in extraintestinal amoebiasis. It is also effective in cyst passing patients. 

Adverse effects include nausea, diarrhoea, abdominal discomfort, headache and goitre (so contraindicated in patients with intolerance to iodine). Prolonged use of iodochlorohydroxyquin causes subacute myelooptic neuropathy (SMON). They are indicated in giardiasis, trichomonas vaginitis, intestinal amoebiasis and amoebic colitis. 

Emetine and dehydroemetine are natural alkaloid obtained from Cephaelis ipecacuanha and synthetic analog respectively. They are effective against tissue trophozoites of . histolytica. It has no effect on cysts but effective in amoebic liver abscess also. It acts by inhibiting protein synthesis by arresting intraribosome translocation of tRNA-amino acid complex. Dehydroemetine is less toxic than emetine and very effective drug for tissue amoebiasis. It is more rapidly eliminated from the body than emetine. 

It is mainly indicated in mild intestinal amoebiasis and asymptomatic cyst passers. 

It is also used in combination with tinidazole (TINIBA DF) and metronidazole (ENTAMIZOLE) in the treatment of intestinal amoebiasis, hepatic amoebiasis and other systemic diseases due to E. histolytica. 

Derivatives of 2-amino-5-nitrothiazole have antiparasitic activity. Niridazole (253) is used in the treatment of schistosomiasis, but its side-effects make it unattractive for treating other diseases, e.g. amoebiasis, for which safer drugs are available. The nitroimidazole metronidazole (254) is particularly useful in amoebiasis and trichomoniasis, and the latter disease may also be treated with nimorazole, l-morpholinoethyl-5-nitroimidazole. 

Amoebiasis. Infection of the gut (amoebic dysentery) or liver (amoebic hepatitis) by the protozoan Entamoeba histolytica. 

Iron-deficiency anaemia is the most common type of anaemia. Red blood cells often appear hypochromic (paler than usual) and microcytic (smaller than usual). Iron-deficiency anaemia is caused by insufficient dietary intake or absorption of iron, or by loss of blood, for example bleeding lesions of the gastrointestinal tract. Worldwide the most common cause of iron-deficiency anaemia is parasitic infestation (hookworm, amoebiasis, schistosomiasis and whipworm). 

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