Antiparasitics

Question 1

Selamectin

Revolution (Zoetis) /Paradyne (VCA)

Answer 1

Macrocyclic lactone

Binds to glutamate-gated chloride channels and hyperpolarizes neuromuscular junctions of insects and helminthes

Flea (Aduliticide, larvicide, ovicide), anthelmintic, tick (R.sanguineus, D. variabilis), hw (no microfilariae), ear mites, roundworm, hookworms

In dogs-American dog tick and Scabies (q 2wks, 3 x)

Question 2

Fipronil

Frontline (Merial)

Answer 2

GABA chloride channel antagonist

Fleas, ticks, mites-otodectes

Question 3

Fipronil +methoprene (not UV light stable)

Frontline Plus (Merial)

Answer 3

Fipronil -GABA chlorid channel antagonist

Methoprene kills ova and larvae, insect growth regulator

Frontline Plus-tickes, mites (otodectes), fleas, mosquitoes

Question 4

Imidaclopromid

Advantage (Bayer)

Answer 4

Imidaclopromid-Irreversibly bind at nicotinic Ach receptor sites on the parasite

Fleas only

Question 5

Imidaclopromid+pyriproxyfen

Advantage II (flea only) (Bayer)

Answer 5

Imidaclopromid-Irreversibly bind at nicotinic Ach receptor sites on the parasite

pyriproxyfen-insect growth regulator/juvenile hormone analog that prevents larvae from development into adults

Fleas only

Question 6

Imidaclopromid + permethrin

Advantix (Bayer)

Answer 6

Imidaclopromid-Irreversibly bind at nicotinic Ach receptor sites on the parasite

permethrin - keeps sodium channel open

Do not use in cats!

Fleas (adulticide), ticks (R. sanguineus, D. variablis, A. americanum, Ixodes), mosquitos, flies, lice (tunga penetrans)

Question 7

Imidaclopromid + moxidectin

Advantage Multi (Bayer)

Answer 7

Imidaclopromid-Irreversibly bind at nicotinic Ach receptor sites on the parasite

Moxdectin-gluatmate gated chloride ion channel

Fleas(adulticide, larvicide), heartworm, roundworms, hookworms, whipworms, lice (trichodectes), mites (otodectes cynotis, demodex canis, sarcoptes)

Question 8

Nitenpyram

Capstar (Novartis)

Answer 8

Acitivates insect specific nicotinic acetylcholine receptors

Age: for dogs and cats>4 weeks old
Dose by size; freq: 24 hours, can be used with lufenuron for sustained effect

Flea adulticide only

Question 9

Dinotefuran/Pyriproxifen

Vectra / Simpleguard -no perimtherin

Answer 9

Dinotefuran-mimics Ach

Pyriproxifen-insect growth regulator
-mimics insect juvenile growth hormone, halting development during metarmorphosis and larvae development. Also concentrates on female flea ovaries, causing non-viable eggs to be produced.

Fleas only

Question 10

Dinotefuran + Pyriproxifen + Permethrin

Vectra 3D

Answer 10

Dinotefuran-mimics Ach

Pyriproxifen-insect growth regulator
-mimics insect juvenile growth hormone, halting development during metarmorphosis and larvae development. Also concentrates on female flea ovaries, causing non-viable eggs to be produced.

Permethrin-keeps sodium channel open

Vectra 3 D- Repels and kills fleas, ticks, mosquitoes, biting and sand flies, lice and mites (excluding mange mites)
Fleas-eggs, larvae, pupae, adults

Question 11

Spinosad

Comfortis (Elanco) / Acuguard (VCA)

Answer 11

Dinotefuran-mimics Ach

Pyriproxifen-insect growth hormone mimic to prevent molting
Nonbacterial tetracyclic macrolide; activates nicontic Ach receptors on parasite (involuntary muscle contracts)

DO NOT USE WITH IVERMECTIN (may cause ivermectin toxicity)
Do not use in seizure patients

Flea adulticide

Question 12

Spinosad + milbemycin

Trifexis (Elanco) / Comobguard (VCA)

Answer 12

Spinosad- Nonbacterial tetracyclic macrolide; activates nicontic Ach receptors on parasite (involuntary muscle contracts

Milbemycin -macrolide related to avermectin; open glutamate sensitive chloride channels

DO NOT USE WITH IVERMECTIN (may cause ivermectin toxicity)
Do not use in seizure patients

fleas, adult hookworm, roundworm & whipworm

Question 13

Amitraz

Mitaban (Upjohn)

Answer 13

Inhibits monoamine oxidase in mites (demodex)

Causes sedation in dogs (α2 agonist); PUPD< bradycardia, hypothermia, hyperglycemia, seizures
Do not use pets / people taking other MAOI, selegiline or diabetic people.
Age for dogs and pups> 8 weeks, freq 42 days for flea, 30 days for ticks

Demodex mites

Comes in dip (mitaban) and collar (Preventic)

Question 14

Amitraz

Preventic (Virbac)

Answer 14

Causes sedation in dogs (α2 agonist); PUPD< bradycardia, hypothermia, hyperglycemia, seizure. Do not use pets / people taking other MAOI, selegiline or diabetic people.

Kills tick and demodex mitess

Collar

Question 15

amitraz +metaflumizone

Promeris (Pfizer) - discontinued
Promeris Duo, Promeris for dogs

Answer 15

Amitraz -Inhibits monoamine oxidase in mites

metaflumizone -just kills fleas by disrupting flea neural axonal impulses-binds sodium channels causing insect paralysis

Topical flea preventative

Promeris-Fleas (adulticide), tickes, Ixodes, dermacenter, A. americanum, R. sanguineus, mites (Demodex canis)

Question 16

metaflumizone

Promeris (Pfizer) - discontinued

Answer 16

metaflumizone -just kills fleas by disrupting flea neural axonal impulses-binds sodium channels causing insect paralysis

Fleas only

Question 17

Lufenuron/milbemycin oxime

Sentinal (Novartis) -HW +Fleas

Lufenuron

Program (Novartis) - kills developing fleas only

Milbemycin oxime

Interceptor (Novartis)- fleas only

Answer 17

Lufenuron-inhibits the production of chitin in larval fleas

Milbemycin-opens glutamate gated chloride channels in neurons of invertebrates causing hyperpolarization

Fleas (larvcide, ovicde), nematodes (d. immitis, ancylostoma, toxocara, trichuris vulpis)

No longer available

Question 17

Dinotefuran

Answer 17

3rd generation neonicotinoid class insecticide

Binds to nicotinic receptors in the nerve synapse, causing continuous nerve stimulation and death of insect

Vectra- has pyriproxyfen too
Vectra 3d- dogs only bc has permethrin

Question 18

Fipronil

Answer 18

An insecticide and acaricide in the phenylprazole class.

Acts as an antagonist at the gamma- aminobutyric acid (GABA)
receptor

Frontline spray or spot on

Use for non-follicular mite and lice
Ticks in dogs

Toxic to rabbits

Question 19

Formamidines

Answer 19

Acaricidal agents act by inhibition of monoamine oxidase. They are also prostaglandin synthesis inhibitors and alpha-adrenergic agonists.

Amitraz available as rinse, spot-on, and collar.

Good to kill demodex, feline demodex, chyeletiella, otodectes, sarcoptic, and notedres

Examples: Mitaban rinse( zoetis), certificate spot application (merial), preventic (vibrac)-doesn’t help demodex

Unstable and oxidizes rapidly when exposed to air and sunlight therefore, do not use expired product.

Side effects of Amitraz: transient sedation, pruritus, hypothermia, bradycardia, hypotension, hyperglycemia (be careful in DM patients)

Question 20

Insect growth regulators

Answer 20

Two types
1) juvenile growth hormone analogs
Prevents maturation of pupae to larvae
Ex. Methorprene, fenoxycarb, pyriproxyfen

Adult fleas exposed continuously to pyriproxyfen die of internal organ damage after 5-10 days of exposure. During feeding the flea is exposed to the agent and the eggs fall off. These eggs do not hatch.

2) chitin synthesis inhibitors

Question 21

Imidacloprid

Answer 21

Chloronicotinyl nitroguanidine class.
It binds to the flea’s nicotinic receptor on the post synaptic neuron and blocks impulse transmission.
Kills fleas and lice

Advantage II has pyriproxyfen

Advantix II has permethrin and kills ticks, biting flies, and Mosquitos too

Advantage multi has moxidectin which kills heart worm, various GI worms, fleas and live. The European product which has the identical formulation is also labeled to kill lungworms, ear mites, scabies and demodicosis

Question 22

Metaflumizone

Answer 22

Semicarbazone
Blocks sodium channels in insects resulting in nerve paralysis.

Promeris (Fort Dodge)
Associated with drug triggered pemphigus foliaceus and has been withdrawn from market

Question 23

Pyrethrin

Answer 23

Volatile oil extract of the chrysanthemum flower
Can be rapidly inactivated by UV light.
Bc of low toxicity, rapid inactivation, and lack of tissue residue and buildup so relatively environmentally safe but still toxic to fish and bees.

Cats may develop cns tox in piperonyl butoxide.

Pyrethrin is effective against fleas, otodectes, flies, lice, and mosquitoes

Question 24

Sulfur

Answer 24

Lime sulfur dip (lime plus dip by Dechra)

Very safe. Inexpensive.
Txt for nonfollicular mites (sarcoptes, notoedres, chyeletiella, chiggers, fur mites and lice), fungicidal, bactericidal, keratolytic, antipruritic.

Drawbacks: fowl odor, stains jewlery, temporarily discolors hairs (white)

Question 25

Macrolytic lactones

Avermectin ( ivermectin, doramectin, abamectin, selamectin)

Milbemycins (milbemycin, moxidectin)

Answer 25

MOA: potentiating the release and effects of GABA. Avermectins are also agonists of glutamate-gated chloride channels.

Pgp is encoded by MDR-1 or ABCB1. Pgp limits penetration of substances into CNS.

Nt230 (del4) mutation is well known in various herding breeds. Homozygous dogs are susceptible to intoxication, heterozygous are intermediate sensitivity.

Recommend challenge test. 0.05mg/kg po SID, 0.1, 0.15, 0.3, 0.3mg/kg and watch for CNS signs.

The issues is whether therapeutic dosage to treat external parasites is above or below intoxicating dosage

Question 26

Ivermectin

Answer 26

Kills nematodes, microfilaria, sarcoptes, chyeletiella, demodex, notoedres, and otodectes. Ivermectin does not affect trematodes and Cestoda bc GABA is not involved in neurotransmission in those species. Parasite paralysis is main action but also suppresses reproduction. Ticks are not killed but their egg production and molting is suppressed.

Question 27

Milbemycin

Answer 27

Milemycin is like ivermectin but also kills some intestinal parasites.
Used to treat nasal mites, scabies, and generalized demodecosis.

Products with milbemycin:
Interceptor
Trifexis

Question 28

Moxidectin

Answer 28

In USA, only labeled for dogs and cats but in Europe, ferrets too.
In the USA only labeled for fleas but elsewhere, labeled for fleas, lice, ear mite infestation, sarcoptic mange, and demodecosis. Licensed for once every 4 weeks, but need more frequent application if treating other things, especially demodex.

Products with moxidectin:
Advantage multi

Also licensed in cattle to treat: various nematodes, hypoderma sp., mites, lice, and horn flies.

Question 29

Selamectin

Answer 29

Selamectin is a semisynthetic avermectin. It is identified in sebaceous glands, hair follicles, and basal layers of the epithelium. Ok to use in ivermectin sensitive dogs at manufacturer’s recommendation.

Prevents heartworm disease, kills adult fleas and prevents their eggs from hatching, and treats and controls ear mites in cats and dogs. Also treats and controls canine scabies and Dermacentor variablis infestation in dogs.

Revolution

Question 30

Insect development inhibitors

Answer 30

Fleas feeding on treated blood lay eggs that do not hatch or develop beyond the larval stage. Larvae feeding on the feces of treated fleas do not develop.

Product:
Lufenuron (program, sentinel)
-it is a benzoyl phenol urea compound that inhibits chitin synthesis

Question 31

Neonicotinoid

Answer 31

MoA: act at the nicotinic acetylcholine receptor

Nitenpyram( capstar) is a flea adulticide. It exerts it’s action at the postsynaptic nicotinic acetylcholine receptor of the insect. Unlike imidacloprid, which is a paralytic, nitenpyram produces hyperexcitability. It is rapidly absorbed and kills 100%in 3-4 hours but no activity after 48 hours.

Question 32

Spinosad

Answer 32

Moa: activity occurs at the nicotinic acetylcholine receptor but does not interact with known insecticidal binding sites of other nicotinic or GABA-ergoc insecticides. It produces hyperexcitability, paralysis, and death of the insect.

Adverse neurological side effects may occurs when co-administered with high dose ivermectin. Data suggest Spinosad acts as a Pgp inhibitor, with resultant increased blood and CSF levels of ivermectin.