Amoebiasis, intestinal

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. 

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. 

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. 

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. 

Amoebiasis (Entamoeba histolytica), including both intestinal and extra-intestinal infection... 

The minuta and magna forms excreted in the faeces in intestinal amoebiasis are usually not infectious, as they perish rapidly in the stools once they have been excreted. Today, differentiation can be made between the two forms using molecular biology techniques. Only the cysts are responsible for transmission, but they are not present in the stool in the acute phase infection from the cysts is transmitted by the faecal-oral route and hence only in the symptom-free, chronic stage of the disease. An exact incubation period has not been defined. The latent period may last for several years. 

Intestinal amoebiasis Initially, clinical differentiation must be made between diffuse colonic amoebiasis and the (rare) circumscribed involvement of the colon. Diffuse amoebiasis of the colon may take different courses (1.) asymptomatic, (2.) symptomatic, and (3.) symptomatic, but non-dysenteric. (18)... 

Asymptomatic intestinal amoebiasis may be witnessed both with and without excretion of cysts or the minuta form of the pathogen. It is, however, possible that the tissue is invaded without the appearance of symptoms, so that patients with extraintestinal amoebiasis do not complain of diarrhoea, either at the time of consultation or in the anamnesis. This is obviously of chnical and therapeutic relevance. 

Symptoms of amoebic dysentery are associated with mucosal invasion and ulceration. Mucosal erosion causes diarrhoea, the severity of which increases with the level of invasion and colonization. Symptoms can also be affected by the site of the infection. Peritonitis as a result of perforation has been reported in connection with severe amoebic infection. Extra-intestinal amoebiasis is usually associated with liver infection, causing abscesses and/or enlargement. The abscess appears as a slowly enlarging liver mass and will cause noticeable pain. Jaundice may also occur due to blockage of the bile. Pleural, pulmonary, and pericardial infection results from metastatic spread from the liver, but can also manifest in other parts of the viscera or give rise to a brain abscess. However, these complications are uncommon. 

Also, in Congolese traditional medicine macerations of root bark of V. africana are used as anti- amoebial. Intestinal amoebiasis is one of the current diseases in tropical regions causing diarrhea (4). 

Amoebiasis is marked by two phases of the infection (a) intestinal amoebiasis characterised by dysentery and diarrhea, nondysenteric colitis, amoeboma (amoebic granuloma) and amoebic appendicitis and (b) extraintestinal amoebiasis (hepatic amoebiasis) marked by liver abscess [48],... 

The extracts of the plants of the genus Holarrhena have been used in the Ayurvedic medicine for over 1500 years in the Indian subcontinent for the treatment of parasitic infections. An important plant of this class is H. antidysenterica, whose bark has been used to treat amoebic dysentery in man. The extract of the bark of this plant, called kurchi, conessi or telicherry bark, contains several alkaloids of which the major one is conessine (8) [32,33]. This alkaloid has been used in the treatment of intestinal and extraintestinal amoebiasis in humans [34,35]. However, neither conessine nor its structural analogues find use in the modern therapy of human amoebiasis [36]. 

A Mannich reaction with 5-halo-8-hydroxyquinolines has led to a series of 7-aminomethyl-5-halo-8-hydroxyquinolines with potent in vitro and in vivo activity against E. histolytica [116]. The most effective compound was found to be 7-(N,N-diethylaminomethyl)-5-chloro-8-hydroxyquinoline (79) [117], which exhibited activity against intestinal amoebiasis in man [112]. 

Like nitrofurans, the compounds of this class have been found to possess a wide-spectrum of antiparasitic activity. The first compound which exhibited potent antitrichomonal activity is entramin (13) [13]. Acylation of entramin gave a number of active compounds the most effective compound was 2-acetylamino-5-nitrothia-zole (acinitrazole, 14). This compound exhibited high in vitro and in vivo activity against Trichomonas vaginalis and T. foetus in animals, but did not prove to be of value in clinical trials [13-16]. Acinitrazole has, however, been found to be effective against intestinal amoebiasis in rats and dogs [13]. 

A number of N-(4-substituted benzyl)acetamides of the general formula 7 were synthesized, which showed promising antiamoebic activity. The most effective compounds of this series were 8 and 9 of which chlorphenoxamide, clefamide (9), was found to be useful in treating intestinal amoebiasis in human [15-18]. Replacement of the OH group in clefamide with OEt gives etofamide (10), which exhibited a high order of amoebicidal efficacy [19]. 

Vanadium compounds containing thiosemicarbazide- and hydrazide-derived ligands, such as 26 and 27 in Figure 5.15, exhibit antiamoebic activity against Entamoeba histolytica. This water-borne amoebic protozoan parasitises the human intestines and in some cases other visceral organs, especially the liver. It is the aetiological agent of amoebiasis (also known as amoebic dysentery) and thus responsible for amoebic colitis and intestinal and liver abscesses. Symptomatic patients typically suffer from abdominal pain, diarrhoea... 

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