Antiamoebic Agents

Antiamoebic agents are compounds of drugs used to cure amoebiasis, a parasitic illness carried by a protozoan bloodsucker known as entamoeba histolytica. Entamoeba histolytica is a disease with adverse effects, especially on dwellers of tropical regions with unhygienic surroundings and poor sanitisation. It may be difficult to diagnose as its appearance can be similar to other parasites when observed under a microscope. These parasites are also known as amebicides. Amebicide drugs can be classified into two different categories based on their site of action, which can be distinguished in three areas where these parasites prevail. Its first line of antiamoebic agents that act on tissue amebicides include ornidazole, metronidazole, and secnidazole. The second-line agents that act on luminal amebicides include chloroquine phosphate, emetine hydrochloride, etc.

Explanation of Key Terms

Amoebiasis

Amoebiasis is a disease caused by entamoeba histolytica and is a significant concern, especially in developing nations with unhygienic sanitary conditions. Individuals who encounter symptoms of amebiasis are generally present with amebic infection along with ulcers and a harrowing amebic pus collection in the liver. Therefore, the abscess eventually results in the spreading of the illness. Infection can spread when sufferers do not hygienically dispose of excreta or fail to sanitise their hands after using the washroom. Infected hands can circulate parasites via food consumed by others and surfaces that may come in contact with others. Hands also get infected while changing the nappies of infected babies.

Amebicides 

Amebicides or antiamoebic agents remove trophozoites but not cysts of entamoeba histolytica and effectively eradicate intestinal and extraintestinal tissue infections. There are various antiamoebic agents which act differently. Amebicide drugs are distributed to all tissues and body fluids such as milk, saliva, and cerebrospinal fluid; these are assimilated by corrosion in the liver, followed by a conjugation reaction which synthesises supplementary water-soluble solvents by incorporating an element with an endogenous molecule to improve excretion of that substance. It is urinated as a constant drug and butyrate. Amebicide drugs have certain detrimental effects like abdominal discomfort causing oral infections, including metallic taste, and vomiting/nausea. Their actual purpose is to eliminate the amoebic parasites in living beings. These drugs are taken through the mouth (orally) or a tube or needle inserted directly into veins (intravenously) because the absorption of an antiamoebic is quick and complete.

Diagnosis of Amebiasis

It is not always easy to diagnose amebiasis. Its appearance is similar to other parasites while observed through a microscope, and so it is commonly believed to be incapable of causing disease (nonpathogenic). A doctor may recommend a stool test and an antigen test to individuals with amoebiasis. An antigen test involves the insertion of a toxin or other foreign substance that induces an immune response in the body, especially the production of antibodies.

Exams and Tests

• In general, patients are advised a stool test on several days to detect the bloodsucker. The amoebas may vary and be very low in number to be correctly read from a single stool test. The ELISA (enzyme-linked immunosorbent assay) stool test, a gold standard procedure to examine a vast spectrum of target molecules boosted with suitable member molecules, is most commonly recommended.
• A blood test or nasal swab, a microscopic PCR (polymerase chain reaction) test is also referred to identify entamoeba histolytica. 
• The disease becomes incapable of being diagnosed through stool once it reaches outside the intestine. Then the physician would further recommend a CT scan or ultrasound. 
• If wounds appear, extracting a substance from the wound via a needle is recommended for the abscess in the liver caused by amebiasis.
• Lastly, a test using a piece of pliable fibre-optic equipment to be entered via the anus to assess the intestine (colonoscopy) can be referred to as an essential method to look for the parasite.

Treatment of Amebiasis

Antiamoebic agents are compounds of the drugs to cure amoebiasis. These parasites are also known as amebicides. These amebicide drugs can be classified into two categories based on their site of action, which can be distinguished in three areas where these parasites prevail. The first line of antiamoebic agents that act upon tissue amebicides include ornidazole, metronidazole, and secnidazole. The second-line agents that act upon luminal amebicides include chloroquine phosphate, emetine hydrochloride, etc.

Metronidazole

Individuals analysed with amoebic parasites are recommended metronidazole. It is currently the standard therapy for treating adults and children with encroaching Amoebiasis. Unfortunately, it doesn’t prove enough to remove the amoebic abscess in the intestine. Metronidazole renders nasty effects like rashes on the skin, digestive issues, bad taste, stomach aches, etc. Therefore, parasite stubbornness to this drug has resulted in the evolution of substitute drugs. Although this dose may have adequate activity against trophozoites and cysts, the widespread assumption is that metronidazole alone is not reliably effective in eradicating cysts in the colonic lumen due to its failure to reach adequate therapeutic concentrations in the large intestines. Thus, the general recommendation is that patients with invasive amoebiasis should receive a luminal amoebicide after treatment with a tissue amoebicide to eliminate any surviving organisms in the colon.

Secnidazole

Secnidazole, the other antiamoebic agent, is used to treat infection of the intestine with a subphylum mastigophora (flagellate protozoan), which causes diarrhoea and other diarrhoea symptoms like amoebiasis. It is available as a pill to be consumed orally. Certain measures should be considered seriously before consuming this medicine in alcoholics and individuals with a history of blood disorders. Its adverse effects include mouth ulcers, digestive issues, and stomachache. Sometimes, rashes and the decreasing count of WBC may also be seen as side effects.

Ornidazole

Ornidazole, another antiamoebic agent, is used to cure amoebiasis. It is available as a pill to be consumed orally. Physicians suggest various preventive measures for those with a history of neurological disturbances followed by relapses of sensory disorders, loss of consciousness, seizures relevant to the abnormal programmed activity in the brain (epilepsy), exceptional rigidity of body tissue (sclerosis), stomach and intestine disease, and pregnant and breastfeeding women. It may result in nausea or sleepiness. Driving vehicles or operating machinery on this medication is not recommended. Side effects include CNS (Central Nervous System) nausea, severe headache, quivering, inability to bend or be forced out of shape, partial epilepsy, exhaustion, non-permanent unconsciousness, and swooning. In addition, uncommon side effects include vomiting, liver impairment, rashes, itching, inflammation, etc. Therefore, a substitute for ornidazole is often preferred.

Conclusion

Amebicides or antiamoebic agents remove trophozoites but not cysts of entamoeba histolytica and effectively eradicate intestinal and extraintestinal tissue infections. Various antiamoebic agents act differently depending on the parasite spread in the body. Though it is difficult to diagnose the correct amoebiasis because of its similar appearance to other amoebic parasites, medical science has made progress in examining it through various tests like ELISA, microscopic PCR, etc. Besides these, many antiamoebic agents like ornidazole, metronidazole, and secnidazole are also available in the contemporary era. These are a boon because the immersion of the antiamoebic is quick and complete.