Anthelmintic_Drugs.pdf

Pharmacology Chemotherapy Anthelmintic Drugs Anthelmintic Drugs Content: Drugs for the Treatment of Nematodes ………………………………… 4 Drugs for the Treatment of Trematodes ………………………………… 15 Drugs for the Treatment of Cestodes ………………………………… 19 Anthelmintic Drugs Anthelmintic Drugs: The three primary groups of...

Pharmacology Chemotherapy Anthelmintic Drugs Anthelmintic Drugs Content: Drugs for the Treatment of Nematodes ………………………………… 4 Drugs for the Treatment of Trematodes ………………………………… 15 Drugs for the Treatment of Cestodes ………………………………… 19 Anthelmintic Drugs Anthelmintic Drugs: The three primary groups of helminths (nematodes, trematodes, and cestodes) that infect humans. Anthelmintic drugs are designed to target metabolic processes present in the parasites but not in the host. The goal of these drugs is to eliminate the organisms from the host and control the spread of infections. Drugs for the Treatment of Nematodes Drugs for the Treatment of Nematodes Nematodes, elongated roundworms with a complete digestive system, cause infections in the intestines, blood, and tissues. A. Mebendazole: A synthetic benzimidazole compound, is a first-line treatment for whipworms, pinworms, hookworms, and roundworms. It acts by binding to parasite β-tubulin, inhibiting microtubule polymerization, and expelling affected parasites in feces. Drugs for the Treatment of Nematodes A. Mebendazole: Adverse Effects: Include abdominal pain and diarrhea, with rare but serious effects like convulsions in infants and an increased risk of Stevens–Johnson syndrome or toxic epidermal necrolysis when combined with metronidazole. Mebendazole is contraindicated in pregnancy. Drugs for the Treatment of Nematodes Drugs for the Treatment of Nematodes B. Pyrantel Pamoate: Pyrantel pamoate is an effective treatment for pinworm and hookworm infections, particularly in the intestines. It functions as a depolarizing neuromuscular blocking agent, causing acetylcholine release and cholinesterase inhibition, resulting in worm paralysis and expulsion. Due to its poor absorption after oral administration, it mainly acts locally. Adverse effects: are generally mild and include nausea, vomiting, and diarrhea. Drugs for the Treatment of Nematodes C. Ivermectin: Ivermectin is the drug of choice for cutaneous larva migrans, strongyloidiasis, and onchocerciasis (river blindness). It also finds efficacy in treating scabies and head lice through a topical formulation. Effective by targeting glutamate-gated chloride channel receptors, enhances chloride influx, leading to hyperpolarization, paralysis, and death of the worm. Administered orally, it does not easily cross the blood–brain barrier and is contraindicated in pregnancy due to potential risks. Its use in onchocerciasis may induce a Mazzotti reaction, with symptoms alleviated by antihistamines or steroids. Drugs for the Treatment of Nematodes Drugs for the Treatment of Nematodes Drugs for the Treatment of Nematodes D. Moxidectin: Is an alternative to ivermectin for treating onchocerciasis, sharing a similar mechanism of action without affecting adult worms. Its safety in pregnancy is not confirmed, and its use can lead to the Mazzotti reaction due to the death of microfilaria in onchocerciasis. Drugs for the Treatment of Nematodes E. Diethylcarbamazine: Diethylcarbamazine is the preferred treatment for filariasis caused by Wuchereria bancrofti, Brugia malayi, or Brugia timori. It effectively kills microfilariae and targets adult worms. Administered orally with meals, the drug is rapidly absorbed and primarily excreted through urine. Adverse effects: include fever, nausea, vomiting, arthralgia, and headache. Drugs for the Treatment of Trematodes Drugs for the Treatment of Trematodes Drugs for the Treatment of Trematodes Trematodes, or flukes, are flatworms with a leaf-shaped structure, and they are identified based on the tissues they infect, such as the liver, lung, intestine, or blood. A. Praziquantel: Is the preferred treatment for various parasitic infections, including schistosomiasis, most trematode infections (excluding fascioliasis), and certain cestode infections like taeniasis. Its mechanism involves inducing contracture and paralysis in parasites by enhancing cell membrane permeability to calcium. The drug is rapidly absorbed orally and should be taken with food. Metabolized extensively, inactive byproducts are primarily excreted through urine. Drugs for the Treatment of Trematodes A. Praziquantel: Common side effects include dizziness, malaise, headache, and gastrointestinal disturbances. Phenytoin is contraindicated. Notably, praziquantel should not be used to treat ocular cysticercosis due to the risk of irreversible damage to the eye. Drugs for the Treatment of Trematodes B. Triclabendazole: Is a benzimidazole derivative used to treat fascioliasis caused by liver flukes (Fasciola hepatica and Fasciola gigantica). It is inhibiting tubulin function, protein synthesis, and enzyme synthesis. Common side effects include abdominal pain, hyperhidrosis, and nausea. Its use in pregnancy should be approached with caution due to limited available data. Drugs for the Treatment of Cestodes Drugs for the Treatment of Cestodes Cestodes, commonly known as "true tapeworms," are characterized by a flat, segmented body that attaches to the host's intestine. Similar to trematodes, tapeworms lack a mouth and digestive tract throughout their life cycle. A. Niclosamide: No longer available in the United States, serves as an alternative to praziquantel for treating taeniasis, diphyllobothriasis, and other cestode infections. Its mechanism involves inhibiting mitochondrial phosphorylation of adenosine diphosphate in the parasite, causing lethality for the cestode's scolex and segments, but not for the ova. Drugs for the Treatment of Cestodes A. Niclosamide: To enhance efficacy, a laxative is administered before oral intake to purge the bowel of dead segments and improve ova liberation. It is recommended to avoid alcohol within 1 day of niclosamide use. Drugs for the Treatment of Cestodes b. Albendazole: Albendazole, a benzimidazole derivative, is effective against a broad spectrum of nematodes by inhibiting microtubule synthesis and glucose uptake. Its primary therapeutic use is in treating cestodal infestations, particularly cysticercosis and hydatid disease caused by the larval stage of Echinococcus granulosus. Additionally, Albendazole is effective against microsporidiosis, a fungal infection. Despite erratic absorption, its uptake is improved with a high-fat meal. Prolonged treatment for hydatid disease carries a risk of hepatotoxicity, agranulocytosis, or pancytopenia, necessitating regular monitoring of blood counts and liver function tests every two weeks.