Questions and Answers
What are anthelmintics?
What are vermifuges used for?
Expelling parasites from the intestinal tract
What are vermicides?
Agents which can kill intestinal parasites and expel them out
List the properties of an ideal anthelmintic.
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The selectivity of action of anthelmintics in helminth parasites depends on what factors?
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Except for ____, the other commonly used anthelmintics do not normally produce pharmacological effects.
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Most anthelmintics may be used in all domestic animal species.
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In which species cannot levamisole be used?
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Praziquantel can only be used in which species?
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Piperazine salts can only be used in which species?
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Salicylanilides can only be used in which species?
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Nitroxynil can only be used in which species?
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Clorsulon can only be used in which species?
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What drugs are in the Benzimidazoles (carbamates) class?
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What drugs are in the Benzimidazoles (thiazoles) class?
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What drugs are in the Probenzimidazoles?
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What drugs are in the Imidazothiazoles?
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What drugs are in the Tetrahydropyrimidines class?
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What drugs are in the Organophosphate compounds class?
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What drugs are in the Macrocyclic lactones (avermectins) class?
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What drugs are in the Macrocyclic lactones (Milbemycin) class?
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What drugs are in the Piperazine compounds class?
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What drugs are in the Benzenedisulphonamide class?
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What drugs are in the Isoquinoline class?
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What drugs are in the Salicylanilide class?
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What drugs are in the Nitrobenzonitrile class?
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What drugs are in the Arsenical compound class?
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Benzimidazoles are typically mostly effective against _______________, but substituted BZDs (carbamate or thiazole ones) are effective against certain _____________?
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Describe the spectrum, safety margin, MOA, pharmacokinetics, and metabolism of benzimidazoles.
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Study Notes
Anthelmintics Overview
- Anthelmintics are drugs designed to kill and expel parasitic worms from the body.
- Vermifuges are agents that specifically expel parasites from the intestinal tract.
- Vermicides not only expel but also kill intestinal parasites.
Ideal Anthelmintic Properties
- Should have a broad spectrum of activity against both mature and immature parasites.
- Easy to administer with a wide margin of safety.
- Should have minimal withholding periods and be economical.
- Must be selectively toxic to helminth parasites.
Mechanism of Selectivity
- The action of anthelmintics relies on drug receptors being unique or more sensitive in parasites.
- They work by inhibiting essential metabolic processes in the parasite that are either unimportant or absent in the host.
- Pharmacokinetic properties ensure higher concentrations in parasites than in host cells.
Exceptions in Anthelmintics Usage
- Organophosphorus compounds and levamisole are exceptions, having pharmacological effects through specific mechanisms.
- Most anthelmintics can be used across various domestic animal species, with exceptions for specific drugs like levamisole and praziquantel.
Species Specificity of Anthelmintics
- Levamisole is not suitable for horses and cats.
- Praziquantel is only approved for use in dogs, cats, and horses.
- Piperazine salts are restricted to monogastrics.
- Salicylanilides, nitroxynil, and clorsulon are only for ruminant species.
Classes of Anthelmintics
- Benzimidazoles (carbamates) include Albendazole, Fenbendazole, Mebendazole, Oxfendazole, Oxibendazole, Parbendazole.
- Benzimidazoles (thiazoles) consist of Thiabendazole and Cambendazole.
- Probenzimidazoles are inactive until converted to active forms by ruminal microbes or the liver, including Netobimin and Febantel.
- Imidazothiazoles consist of Levamisole and Tetramisole.
- Tetrahydropyrimidines include Pyrantel, Morantel, and Oxantel.
- Organophosphate compounds include Dichlorvos, Trichlorfon, Haloxon, Coumaphos, and Crufomate.
- Macrocyclic lactones (avermectins) include Ivermectin, Abamectin, Doramectin, Eprinomectin, and Selamectin.
- Macrocyclic lactones (Milbemycin) consist of Milbemycin oxime and Moxidectin.
- Piperazine compounds include Piperazine and Diethylcarbamazine citrate (DEC).
- Benzenedisulphonamide refers to Clorsulon.
- Isoquinoline class has Praziquantel and Epsiprantel.
- Salicylanilide class includes Closantel, Oxyclozanide, and Rafoxanide.
- Nitrobenzonitrile class is represented by Nitroxynil.
- Arsenical compounds consist of Thiacetarsamide sodium and Melarsomine.
Benzimidazoles Efficacy
- Generally effective against nematodes; specific substituted benzimidazoles target certain tapeworms and flukes.
- Exhibit broad-spectrum efficacy against gastrointestinal and lung nematodes with a wide safety margin.
- Mechanism of action involves irreversible binding to β-tubulin in nematodes, preventing microtubule formation.
- Resistance development in parasites is often due to variations in β-tubulin.
Pharmacokinetics of Benzimidazoles
- Lower aqueous solubility leads to poor gastrointestinal absorption.
- Clinical application demands consideration of pharmacokinetics for effective treatment outcomes.
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Description
This quiz covers the essential properties and mechanisms of action of anthelmintics, drugs used to combat parasitic worms. It includes details on vermifuges, vermicides, and the selectivity of these agents based on their interaction with parasites. Test your knowledge on the unique characteristics that make an effective anthelmintic and its exceptions in usage.
