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.pharmocology > Ectoparasitic Drugs > Flashcards

Ectoparasitic Drugs Flashcards

1
Q

Ideal ectoparasiticide

A

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

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2
Q

How are ectoparasiticides delievered

A

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

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3
Q

Advantages of ectoparasiticide

A

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

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4
Q

Disadvantages of ectoparasiticide

A

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

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5
Q

Macrocyclic lactones

A

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

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6
Q

Macrocyclic lactones MOA

A

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

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7
Q

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

A

FALSE

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8
Q

Macrocyclic lactones in simple stomach animals

A

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

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9
Q

Macrocyclic lactones in ruminal absorbtion

A

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

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10
Q

Macrocyclic lactones in ruminants

A

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

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11
Q

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

A

The slow disposition kinetics present

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12
Q

Selamectin uses

A

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

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13
Q

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

A

Selamectin
Sarcoptic mange

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14
Q

Toxicity of Macrocyclic lactones

A

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

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15
Q

Macrocyclic lactones and collies

A

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

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16
Q

Spinosad MOA

A

Mix of 2 macrocylic lactones
Ectoparasite only
Nicotinic AChR allosteric acitvator

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17
Q

What does spinosad do to parasites?

A

Involuntary muscle contraction and tremors → death

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18
Q

Spinosad uses

A

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

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19
Q

Spinosad toxicity

A

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

20
Q

Fipronil PK

A

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

21
Q

Fipronil MOA

A

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

22
Q

Fipronil uses

A

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

23
Q

Reported activity of fipronil

A

Sarcoptes, otodectes, trombicula, cheyletiella, trichodectes

24
Q

Fipronil safety/ toxicity

A

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

25
Q

Imidacloprid and Nitenpyram MOA

A

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

26
Q

Imidacloprid PK

A

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

27
Q

Imidacloprid uses

A

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

28
Q

Side effects/ toxicity of imidacloprid

A

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

29
Q

When shouldn’t imidacloprid be given?

A

Puppies <7w old or kittens <4m

30
Q

Nitenpyram (Capstar)

A

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

31
Q

Nitenpyram (capstar) uses

A

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

32
Q

3rd generation pyrethroids

A

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

33
Q

MOA of pyrethroids

A

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

34
Q

Pyrethroid uses

A

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

35
Q

Pyrethroid toxicity in cats

A

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

36
Q

Pyrethroid toxicity tx in cats

A

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

37
Q

Amitraz (Formamidine) MOA

A

Inhibits monoamine oxidase in CNS

38
Q

Amitraz uses

A

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

39
Q

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

A

Taktic (amitraz)

40
Q

Safety/ toxicity of amitraz

A

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

41
Q

Signs of amitraz toxicity

A

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

42
Q

Tx of amitraz toxicity

A

Atipamezol (alpha-2 antagonist)

43
Q

Juvenile hormone analogs (insect growth regulators)

A

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

44
Q

Insect development inhibitors (insect growth regulators)

A

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

45
Q

Isoxazoline drugs

A

Fluralaner**, afoxolaner, sarolaner

46
Q

Isoxazoline MOA

A

Block GABA and glutamate-gated chloride channels

47
Q

Isoxazoline uses

A

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

.pharmocology (21 decks)

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