Lecture 23 Flashcards
What is an example of the pyrethrin and the pyrethroids?
allethrin, phenothrin, permethrin
What is the mechanism of action of the pyrethrin and the pyrethroids?
Affects the sodium channels capacity to depolarize causing death of the parasite (1000 times more selective for insects than for animals)
What is the main genera of parasite that is targeted by the pyrethrin and the pyrethroids?
Insects
What is it important not to use a dog pyrethrin and the pyrethroids on a cat?
The concentrations used on cats are typically much lower than those used on dogs
What are the two different types of insect growth regulators and how do they work?
Methoprene - is a hormone growth antagonist meaning that the insect will not grow up
Triflumuron - inhibits the chitin synthesis pathway meaning that the insect is unable to develop
Why is there a lag period in the use of insect growth regulators (IGR’s)?
Lag period as effective control is not achieved for several weeks. It is not adulticidal (however this can be fixed by giving it with an adulticide)
How safe are the insect growth regulators?
Considered to be incredibly safe - a very high lethal dose is required they are classed as a schedule zero.
What is the mechanism of action of fipronil?
spastic paralysis
What are the pharmacokinetics of fipronil?
very lipophilic and with limited systemic absorption
What adverse reactions in the host can fipronil cause?
Host toxicity that causes hyperactivity and convulsions
What is the mechanism of action of the drug Imadacloprid?
Insect paralysis
How safe is the use of the drug imidacloprid?
Very safe there is little binding to mammalian receptors and hence it is considered to be very safe
What is the mechanism of action of the drug spinosad?
paralysis and death
How toxic is the drug spinosad to the human population?
Limited toxicity to people and hence no wool re-handling period and no wool harvesting interval
Briefly explain how the selective toxicity of Indoxacarb works:
It causes neurotoxicity in fleas. It is metabolized into active metabolite in the flea. It is metabolized into a relatively inactive substance in non-target insects and mammalian hosts.
