Ectoparasitic Drugs Flashcards by Trenni Jefferson

Ideal ectoparasiticide

Effective repellent and adulticide
Persistent in blood/ skin for 1-3m
Stable in sunlight and water/ shampoo

How well did you know this?

Not at all

Perfectly

How are ectoparasiticides delievered

Transdermal
Lipophilic with large molecular wt.
Slow dermal absorption, low bioavailibility, large distribution, long t 1/2

How well did you know this?

Not at all

Perfectly

Advantages of ectoparasiticide

Ease of application
Avoid challenges of first pass metabolism and GI degradation

How well did you know this?

Not at all

Perfectly

Disadvantages of ectoparasiticide

Overdosing by clients (toxicosis)
Licking → oral absorption and systemic exposure
Pour-on food in animals require longer withdrawal pd and long t1/2

How well did you know this?

Not at all

Perfectly

Macrocyclic lactones

Endoectocides (combo of ectocide and endocide): Avermectin(iver, aprino and selamectin) and Mibemycin (Moxidctin)
Spinosad

How well did you know this?

Not at all

Perfectly

Macrocyclic lactones MOA

Toxic against insects, acarines and nematodes
Agonist of ligand-gated Cl channels (glutamade-Cl channel) → flaccid paralysis and inhibits larval development

How well did you know this?

Not at all

Perfectly

T/F: Macrocyclic lactones have efficacy against cestodes and trematodes

FALSE

How well did you know this?

Not at all

Perfectly

Macrocyclic lactones in simple stomach animals

95% absorbed after oral admin
Selamectin greater bioavail. for cats than dogs

How well did you know this?

Not at all

Perfectly

Macrocyclic lactones in ruminal absorbtion

Absorbs 1/4-1/3 dose due to activation in the rumen
Oral bioavail. poor in ruminants

How well did you know this?

Not at all

Perfectly

Macrocyclic lactones in ruminants

Strong absorption to Gi particulate digesta
Fat reservoir
Extensive/ reversible plasma tissue exchange
Low metabolism rate

How well did you know this?

Not at all

Perfectly

The long half-life in ruminants are due to …..

The slow disposition kinetics present

How well did you know this?

Not at all

Perfectly

Selamectin uses

Topical monthly for dogs and cats with ear mites and adult fleas
Prevents flea eggs from hatching

How well did you know this?

Not at all

Perfectly

__________ is the only spot on product approved for control of K9 ____________

Selamectin
Sarcoptic mange

How well did you know this?

Not at all

Perfectly

Toxicity of Macrocyclic lactones

10x safety in most animals
Acute toxicity: depression, ataxia, tremors, salivation, mydriasis, coma and death

How well did you know this?

Not at all

Perfectly

Macrocyclic lactones and collies

P-gp mutation in collies (4 base deletion MDR1/ABCB1 gene)
↑ conc in the brain, safe @ norm doses

How well did you know this?

Not at all

Perfectly

Spinosad MOA

Mix of 2 macrocylic lactones
Ectoparasite only
Nicotinic AChR allosteric acitvator

How well did you know this?

Not at all

Perfectly

What does spinosad do to parasites?

Involuntary muscle contraction and tremors → death

How well did you know this?

Not at all

Perfectly

Spinosad uses

Fleas: kills adults (4hr), prevent egg production
Sheep: blowflies and lice
Control beetles, flies and northern fowl mite

How well did you know this?

Not at all

Perfectly

Spinosad toxicity

Don’t mixed with ivermectin (causes ↑ risk of ivermectin toxicities)

Fipronil PK

Deposits in sebum, sebaceous glands (reservior) and hair follicles
Forms a layer on S. corneum

Fipronil MOA

Acts on CNS target parasites
Active metabolites: fipronil sulfate (potent inhibitor)

Fipronil uses

Adult fleas
All stages of brown dog, American dog, long star and deer tick (on animal)
Kills larvae and eggs

Reported activity of fipronil

Sarcoptes, otodectes, trombicula, cheyletiella, trichodectes

Fipronil safety/ toxicity

Slight skin/ eye irritation
Risk ↑ with oral ingestion
GABA receptor antagonist (hyperactvity, excitability and convulsions)

Imidacloprid and Nitenpyram MOA

Mimics effect of ACh by competitive inhibition @ post-syn. nicotinic AChR (CNS of insects)

Imidacloprid PK

Surface translocation aided by body movement Efficacy depends on contact with ectoparasites Topical

Imidacloprid uses

Taken up by flea body contact with drug (dogs and cats) Kills adult and larva fleas (1h) No repellant activity

Side effects/ toxicity of imidacloprid

Nicotinic effects and hepatic effects Careful with products because they'll combine (cats)

When shouldn't imidacloprid be given?

Puppies <7w old or kittens <4m

Nitenpyram (Capstar)

Safe and water soluble Readily absorbed (100%) in GI

Nitenpyram (capstar) uses

Oral adulticide for fleas in cats and dogs Rapid onset, kills adult fleas resistant to fipronil

3rd generation pyrethroids

Permethrin Photo stability and potency Spots on high conc, dogs only, no cats

MOA of pyrethroids

Gating kinetics of insect Na ions channels in nerves Channel left open, repetitive discharges or membrane depol

Pyrethroid uses

Repellent and knock-down effect Ectoparasites of domestic animals Formulated with insect growth regulators, synergists or repellents to ↑ efficacy

Pyrethroid toxicity in cats

Deficient hepatic glucoronidation Grooming after application Muscle tremors, hyperthermia, seizures

Pyrethroid toxicity tx in cats

Wash the coat at home then at clinic Methocarbamol +/- benzodiazepines IVF if severe acidosis

Amitraz (Formamidine) MOA

Inhibits monoamine oxidase in CNS

Amitraz uses

Dogs: gen. demodicosis (mitaban), tick collars Cattle: ticks, mites, biting louse, suckling lice Swine: mange mite and louse

____________ can cause death in horses and dogs if used @ high doses

Taktic (amitraz)

Safety/ toxicity of amitraz

Horse: fatal from colon impaction Cats sensitive Don't use in chihuahuas, preg, nursing bitches, puppies <3m

Signs of amitraz toxicity

Activates alpha-2- adrenergic receptors CNS depression, bradycardia, PU, hyperglycemia, sedation (24hr)

Tx of amitraz toxicity

Atipamezol (alpha-2 antagonist)

Juvenile hormone analogs (insect growth regulators)

Signal insect to remain in immature stage and not develop to adult Methoprene, pyriproxifen, fenoxycarb, cyromazine

Insect development inhibitors (insect growth regulators)

Interferes with development of insect exoskeleton by inhibiting chitin synthesis or deposition pathway Diflubenzuron or lufenuron

Isoxazoline drugs

Fluralaner**, afoxolaner, sarolaner

Isoxazoline MOA

Block GABA and glutamate-gated chloride channels

Isoxazoline uses

Kills fleas and ticks Fluralaner 12 w efficacy Afoxolaner 5 w efficacy