Pharm 2 - Ectoparasiticides

drraythe's version from 2015-11-23 13:01


Question Answer
*(Also key note) What are the routes of dermal absorption & which is most common?
(A) Lateral diffusion
(B) Appenadgeal (Sweat pores)
(C) Transfollicular
( ) Transcellular (Intracellular)
(D) Intercellular (most drugs are absorbed this way)
Key note: MOA of ectoparasiticides: (3 things, some have subtypes)(1) Ectoparasite nervous system: AChE-inhibitors, Na+ channel blockers, nAChR inhibitors, GABA & Cl- channel inhibitors
(2) Ectoparasite repellents
(3) Insect growth & development inhibitors
Mechanism of insect resistance incld (3)(1) ↓ penetration of the drug
(2) ↑ activity of detoxifying enzymes (the cz of cross resistance btwn classes of drugs)
(3) ↓ sensitivity of the target site (changes in Na+ channels lead to diminished binding of Pyrethroids)


Question Answer
MOA of Fipronil?Non-competitive block of the GABA & Glutamate ion channels (Fi likes to GAB when she eats sugar)
What does Fipronil Tx?Txs adult fleas & different stages of a variety of ticks (Fi can only handle so much...F for her name, & T so she can be FIT)
Firponil in what animals?Dogs & cats
Contraindications of Fipronil?DO NOT USE IN YOUNG RABBITS (Fi hates rabbits - FIP THE HARE LIP)
Things to note about Fipronil?FLEAS & TICKS MUST BITE 1st (Fi is covered in bug bites)
Has Fipronil been combined w/ anything?Has been combined w/ IGR (Fi didnt want to get fat, so she has to use Growth Regulators)
How safe?*Wide safety margin, less affinity for mammalian GABA (Fi wouldn't hurt an animal, except rabbits)


Question Answer
What are the 2 drugs in this group?Imidacloprid, Nytenpyram (clop, clop, nyaaannn)
MOA of Imidacloprid?Competitive inhibition of post-synaptic nicotinic receptors (nAChR) (clop right through the nicotine addiction)
Admin of Imidacloprid? Absorption?Topical → does not absorb into the skin (lateral diffusion) – lg. safety margin (it is advantage or w/e when combined w/ the Permethrin or w/e)
Imidacloprid/Nytenpyram is used for Txing? How effective?Adult & larval fleas → RAPID DEATH (only fleabags care about cigarettes)
Thing to note about Imidacloprid?PREVENTS biting (also Tx fleas resistant to Fipronil) (clop it right in the face before it bites)
Has Imidacloprid been combined w/ anything?Combo w/ Permethrin = repel & kill misquotes & ticks on adult dogs (ADVANTIX) (perm your pet clop - it will look like it's from the 80s)
Admin of Nytenpyram?Oral, 100% absorption (you say nyan w/ your mouth)
Contraindications of Neonicotinoids?DO NOT USE IN CATS (cats are bitchy enough w/o a nicotine addiction)
How safe?Wide safety margin (but don't use in cats) (that's a wide clop you made there - musta been painful)

Macrocyclic Lactones (also antinematodal w/ ectoparasite activity)

Question Answer
MOA of Avermectins?Targets ~Glutamate, GABA & glycine gated ion channels (Good Going God, for making MyDumbRetard) ← as much as I don't like using that word, I will do w/e it takes to learn this shit
Contraindications of Avermectins?NOT USED be used in Collies, Bobtails, Shelties → *Toxicity in collies, Bobtails, Shelties (have the MDR1 mutation) bc they target the GABA receptor (mydumbretarded1 → stupid Collies, Shelties & Bobtails)
Which drugs are in the oil pour-on preparations?Erpinomectin & Moxidectin (primo milk on the skin & the moxi to go on any way it wants)
Spectrum of activity of Macrocyclic Lactones?Broad (mac & his broad shoulders)
Which drugs have no withdrawal for milk?Eprinomectin & Moxidectin (the same 1s as oil pour on...& primo milk, moxie to do what it wants w/ no consequences)
Which animal/breed is very susceptible to Macrocyclic Lactones?Dog breed w/ an MDR1 gene mutation

Organophosphates & Carbamates (← BZDs, the most effective 1s)

Question Answer
MOA of Carbamates?Reversible inhibition of AcH esterase (bc Carbamates are like Organophosphates, even tho the anthelmintic say otherwise. also reversible means less toxic)
When are Carbamates unstable?Relatively unstable in alkali environments (cars & organs are not basic things for life)
What do Carbamates Tx?Used against lice, fleas, ticks & sometimes mites (a car full of everyone - lice, fleas, ticks & sometimes mites, if you want the 4th seat filled up)
What are the drugs in Carbamates?Carbaryl, Propoxur, Bendiocarb
MOA of Organophosphates?Irreversible inhibition of AcH esterase (remember? Just like Dichlorvos) (irreversible is also why it's more toxic)
When are Organophosphates unstable?Unstable in alkali environments (cars & organs are not basic things for life)
Which is more toxic, Organophosphates or Carbamates? What are the clinical signs?Organophosphates are more toxic than Carbamates (...they are powerful pesticides, makes sense theyre more toxic) clinical signs similar to stimulation of parasympathetic nervous system
How soluble are Organophosphates?Poorly water soluble (poor water solubility, when was the last time you saw an organ dissolve in water)
What do Organophosphates Tx?Used against lice, fleas, ticks & sometimes mites
What are the drugs in Organophosphates?Coumaphos
Sensitive animals?Brahman cattle, grey hounds, cats
Odd SFx?Delayed neurological effects (can be nicotinic or muscarinic)
CarbarylSpray & dust for dogs & cats
PropoxurFlea collars for dogs & cats
OP → Coumaphos → doesnt Tx what?Ticks

Formamidines (Amitraz)

Question Answer
MOA of Amitraz?Inhibition of monoamino oxidase, Agonistic effects on the α-2 receptors, Agonists of the insect’s Octopamine receptors (so...MAO AmiAmi ← α-2 & she will eat an octopus)
Tox of Amitraz presents as?Intoxications is characterized by α2 – Adrenergic effects such as sedation & colon obstipation ((Ami's trax marks indicate when she ODs, she must be extremely sedated & constipated)
Who is sensitive to Amitraz?Horses & cats are sensitive (horses & cats are sensitive about Ami having traz marks on her arm)
Do NOT use Amitraz in who?DO NOT use in Chihuahuas, pregnant or nursing bitches or puppies less than 3 months old (extremely tiny things, or things that have to deal w/ very tiny things. bc AMI WILL CRUSH THEMMMMM)

Insect Development Inhibitors (IDIs)

Question Answer
MOA?Inhibition of chitin synthesis, Larvicidal - Interfere w/ the synthesis of the exoskeleton (egg shell & larval development) (can't develop w/ no exoskeleton or egg)
What are the 3 drugs in this category?Lufenuron
How can you improve oral bioavail of IDIs?Enhanced w/ food
Which IDI is highly protein bound?Lufenuron (Lu thinks it's fen eating protein)
Contraindications of IDIs?Do not use in lactating animals
LufenuronInhibits chitin synthesis - exoskeleton development

Insect Growth Regulators (IGRs)

Question Answer
MOA?Interferes w/ the hormonal regulation of the maturation process of larvae (larvicidal) - Agonists of the juvenile hormone (cant grow w/o juvenile hormones)
What do you combine w/ these & what do these Tx?Used in combination w/ adulticides in the Tx of fleas (stopping form growing doesnt help w/ fully grown) & grow fleas for alphabetical order
Which drug in this category is susceptible for larval esterases?S-Methoprene (ES-METH for ESTER...i mean easter)
MethopreneJuvenile hormone analogue (Meth will stunt your growth for sure)

Pyrethrins & (synthetic) Pyrethroids

Question Answer
MOA?Interacts w/ the Na+ channels - Targets voltage gated Na channels in axonal membrane; GABA gated Cl channels; mitochondrial ATPase & nicotinic receptors (put salt on a python it will shrivel up like a gabbing nicotine addict)
How does resistance occur in the Pyrethrins & Pyrethroids?Resistance → mutations in Na channels = ↓ binding of the ectoparasiticide to the Na channel
What is the safety like for Pyrethrins & Pyrethroids, & why is it like that?Minimal systemic absorption after dermal application → NO food & milk withdrawal time (pythons arent going to be in your milk & meat)
Admin? Why benefit is related to its PK & the admin?Topical/dermal - Minimal dermal uptake - minimal withdrawal time
Contraindications?DO NOT use in cats → grooming → ingestion. Also Aquatic animals = highly sensitive. (Pythons will eat cats & fishes easily)
Txs what?Fleas, lice, mites, & ticks (repellent effect on flies) (pythons will eat anything)
Allethrin & Phenothrin are used for what?Used as a spot-in formulation against fleas & ticks in dogs (Dogs get ALL the PHEN)
Resmethrin & Permethrin... note about these?Short withdrawal time (The Res is Permanent....unless we withdrawal it, which would give it a short time)
Fenvalerate...note about these?Used in ear tags for cattle (FEN for VAL to put earrings on cows)
Flumethrin & Cypermethrin...note about these?Used as fly repellent spray in horses (horse flew pass the cypresses, repelled by the fire)
Fenvalerate note about SFx?Serious SFx at low doses

Isoxazoline Ectoparasiticides & Oclacitinib

Question Answer
What is the drug in the Isoxazoline Ectoparasiticides?Fluralaner (FLURNER ERH MER SERKS)
MOA of FluralanerSelective inhibition of arthropod GABA & L-Glutamate- gated chloride channels → Binding w/in the chloride channel lumen → Similar effects as Fipronil but different class of drugs (Fi like fluras - flur same as Fipronil MOA)
Oclacitinib is used for what? MOA?New anti-itch drug → MOA: Inhibition of JAK-1 (Janus kinase-1) → Inhibits activation of nerve cells & immune cells by cytokines (Janus lacktit)