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1,592 bytes added ,  11:59, 30 October 2008
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==Modes of Action==
 
==Modes of Action==
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These drugs mainly act on the parasites nervous system and neuromuscular junction. They are selectively toxic by having a greater affinity for the parasite receptor than the animal receptor. They can either by '''contact posions''' - arbsorbed through the parasites exoskeleton, or are '''stomach poisons''' - they are absorbed through the parasites stomach and so the parasite must bite to be affected. Thus the stomach poisons are usually given systemically to the host animal.
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===Insecticides===
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'''Synthetic Pyrethroids - Cypermethrin, Deltamethrin'''
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* Many products and are in widespread use.
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* They increase the permeability of neuronal membranes to sodium ions. This makes the membrane hyperxcitable leading to convulsions and death.
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* In high concentrations these products can cause adverse reactions in cats and dogs.
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* '''Piperonyl butoxide''' is a syngeristic product that is often put in formulations to potentiate the action of the pyrethroids.
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'''Semicarbazones - Metaflumizone'''
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* A new group of insecticides
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* They work be blocking sodium ion channels in the axonal membrane of nerves, this prevents the propagation of nerve impulses leading to paralysis of the insect and hence death.
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'''Organophosphates and Carbamates - Diazinon, Dichlorvos'''
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* Their use has been limited of late as they are potentially neurotoxic to animals and man, and can cause environmental damage.
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* They are anticholinesterases and so resukt in the build up of acetylcholine in the parasites's synapses, leading to paralysis and death.
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'''Neonicotinoids - Imidacloprid, Nitenpyram'''
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*
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