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Pharma midterm 2 ectoparasiticides > Ectoparasiticides > Flashcards

Ectoparasiticides Flashcards

1
Q

What are contact poisons?

A

on the surface of animal, when the parasite lands on body they will be killed

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2
Q

What are systemic agents?

A

drug is inside the animal, when a parasite comes, to suck blood or lymph, they take the drug with them

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3
Q

Insect growth regulators (IGRs):

A

acts against the insects, where there are metamorphosis fleas, flies

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4
Q

Repellents (DEET, pyrethroids):

A

keeps the parasites away from the animal, important against the flies and mosquitos, phlebotome sand flies, ticks

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5
Q

Selective toxicity of the drugs in regards to the pharmacokinetics

A
  • Slow metabolism
  • Blood-brain barrier (eg. P-glycoprotein-pump ivermectin) pumps out the drugs, makes the drugs not so toxic
  • slow absorption, large molecules, very good because in the system of the body the concentration isn’t high enough to cause clinical signs
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6
Q

selective toxicity in regards to pharmacodynamics

A
  • acts on different receptors and channels
  • eg. GluCl channels (only in insects and parasites)  depolarization or hyperpolarization
    o agonizing: open, chloride ions goes inside the cell hyperpolarization  paralysis of the parasite
    Ivermectin (macrolide)
    o antagonist: chloride channels does not open  depolarization excitation
    fibronyl??
  • nACh receptor sensitivity: imidacorporate (Advocate, advantex) antiflea agent, acts against fleas, very
    high selectivity and affinity to the flea nACh receptor compared to mammals or birds
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7
Q

the most common route of administration of ectoparasiticides?

A

Dermal absorption

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8
Q

How is the absorption of ectoparaciticeds?

A

slow but good
they are large, lipophilic molecules
low Cp - not so toxic

prolonged absorption from the site of administration (subcutaneous tissue, sebaceous glands) – continuous and prolonged effect

Poor-moderate amount crosses the blood-brain barrier, if they penetrate the p-glucoprotein pump will protect the nervous system

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9
Q

duration of action in different applications

A
  • collars 4-8 months – impregnanted, slow release
  • spot on 4-12 weeks – not a modified release, put on the skin, addtives helping with prolonged duration
  • spray, bathing days
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10
Q

Organophosphates

chemical characteristics

A

S least toxic (O -> F)
high lipophilicity
sensitive to alkaline pH
becomes more toxic with longer storage

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11
Q

organophospahtes absorption

A

good, lipophilic

less toxic when used dermally

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12
Q

distribution of organophosphates

A

excellent

spcial barriers BBB

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13
Q

metabolism of organophosphates

A

Partial activation – in the liver

Diazinon (t1/2hours)  diazoxon (t1/2 days)

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14
Q

Excretion - organophosphates

A

80% urine metabolites

20% faeces

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15
Q

mechanism of aciton - organophosphates

A

contact poison

irreversibly inhibits acetylcholin esterase

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16
Q

side effects of organophosphate (in connection with receptors)

A

Muscarinic acetylcholine receptor symptoms

  • Bradycardia
  • Bronchoconstriction
  • Myosis
  • GI: emesis, diarrhea
  • Salivation
  • Lacrimation
  • Urination

Nicotinic acetylcholine receptor symptom

  • Excitation
  • Muscle convulsion
  • tremor
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17
Q

antidotes organophosphates

A

SLUDGE - atropine

enzyme reactivation - pralidoxime, obidoxime

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18
Q

application and spectrum - organophosahates

A

broad spectrum in most species - diazinon
fleas, ticks, lice, mites, myiasis

dipping in sheep

varroosis of honeybeeds - coumaphos
- fume strip

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19
Q

carbamates - toxicity, MoA, agent, antidote, pharmacokinetics, spectrum, application

A

Similar to organophosphate, but less toxic

Inhibits acetylcholine esterase reversibly

Agent: propoxur (Bolfo®, Kiltix®)

tropine as antidote)

Pharmacokinetics: less lipophilic, oral vs dermal (LD50 higher than oral one)

Fleas, ticks

Collars (frequent), aerosol sprays, shampoos

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20
Q

generallly about pyrethroids

A

One of the most frequently used endectoparasiticides
Repellent effect, keeps the parasites away
Good against flies, ticks and mosquitos

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21
Q

generations of pyrethroids

A

Tetramethrin (NeoStomosan) : 1st gen.

Permethrin (ExSpot, Advantix, Vectra) :2nd gen.

Deltamethrin (Scalibor) :2nd gen.

Flumethrin (Kiltix, Foresto): 2nd gen.

1st generation: toxicity, residual activity, lower stability

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22
Q

Pyrethroids - mechanism of action

A

increases Na+ channels - constant depolarization
also known as knock down or hot foot effect

contact poison + repellent

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23
Q

resistance - pyrethroids

A

Ticks: still OK
- fipronil-tolerant brown dog tics resistant
Fleas: resistance is common
Poor efficacy against mange mites
Fly control
Moderate efficacy against Varroa mites (resistance!)

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24
Q

name of the products that takes care of varroosis

A

flumehtrin, fluvalinate

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25
Q

application of pyrethroids

A

Foresto can be used in cats – low dose, collar – the release is slow and continuous
spot on – total amount on the surface, large concentration, don’t give to cat

26
Q

toxicity of pyrethroids

A

Safe in warm-blooded animals (↔ cat spot on)
- Tremors, seizures, excitation
Fish are especially sensitive – don’t let dogs go swimming when it has been applied
Antidote Ø
- Can only treat it clinically
Intralipid 20% sequestration
- Contains lipid
- Closes pyrethroid molecules, letting them be excreted before they act in the nervous system
Favourable prognosis in most cases (within 24 hours)
+ LOCAL IRRITATION, ALLERGIC REACTIONS
- White toy breeds
Similar to organophosphate
- Convulsion
- Tremor
- Salvation

Main difference is that the pupils are dilated – mydriasis

27
Q

Amitraz (formamidine) - what neurotransmitter is it most selective to?

A

octopamine (doapmine, noradrenaline, inhibition of serotonine reuptake)

28
Q

amitraz - mechanism of action

A

MAO-inhib. + α2 agonist

29
Q

amitraz - kinetics

A

moderate absorption (p.o. 13% > dermal), half-life 23 hours in dogs

30
Q

amitraz - spectrum

A

MANGE MITES, DEMODEX, ticks, 8-legged arthropods

31
Q

amitraz - application

A

0,025% solution – safe concentration (dipping), collar, impregnated strips

32
Q

amitraz - TI and safety

A

narrow - especially in eg, chihuahua, fe

oral administration is more toxic

storage: light, air

33
Q

amitraz - side effects

A

alpha2 agonist: sedation, vomiting, bradycardia, hypothermia, emesis, hyperglycaemia (not in DM)
Horses: alpha2-agonist, decreases the motility of the GI tract – leads to paralytic ileus

34
Q

amitraz - antidote

A

atipamezole 0.05 mgkg

35
Q

Macrolides - mechanism of action

A

GluCl channel agonist: channel opens and chloride goes in -> hyperpolarization -> paralyzis (only in nematodes and ectoparasites) not acting in mammals and birds

GABA agonist: inhibitory receptor -> leads to paralysis in the animal, p-glucoprotein pump funciton penetrating the BBB, will pump it out before it acts, quite safe in the animal

36
Q

macrolides - spectrum

A

Endectocides
Fleas – only selamectin (stronghold)
Mange mites – all are good (ear mites as well)
Demodex spp (differences!) -> moxidectin (1 weekly – 4 times more frequent – more expensive for owner) and milbemycin (1x daily)
Myiasis – fly larvae infestation
Ticks (slow killing, not repellents) – not enough to prevent the diseases carried by the tick

37
Q

how to test if a dog (breed) is suspecte to have MDR-1 gene missing

A

probe therapy

38
Q

which breeds are predisposed to MDR-1 gene missing?

A
  • Collies (not all are sensitive – individual genetic mutation) 70-75%
  • Australian sheepdog – 50%
  • Bobtail and german shepherd – 10%
  • Shelties and border collies – 5%
39
Q

macolides - products and application

A

Orally - milbemax, nexgard spectra (milbemocyin) milprazon
Spot on – stronghold (selamectin)
Bravecto – amoxidectin
Injection in large animals

40
Q

Fipronil (frontline)

  • MoA
  • disadvantage?
  • applicaiton
A

GABA-antagonist  excitation
Relatively slow effect (8h 40-60%) against parasite, a disadvantage
Spot on, spray (frontline)

41
Q

fipronil - pharmacokinetics

A

A: Good distribution in the skin (sweat and sebaceous glands)  good residual activity (bathing)
can last for 1 month
As a spray only a few days
The animals should not bathe or swim for 48h after application (rainy days)

D: Minimal systemic effect – safe for dogs and cats, no poisonous clinical signs

Shedded hair > 2 weeks (Dermatophagoides farinae) - Allergy management
Skin particles  into the environment

42
Q

animals susceptible for fipronil?

A

rabbits

43
Q

pyriprole

A 
Derivate of fipronil
Similar characteristics, GABA-antagonist  excitation in the parasite
Fleas, ticks  decreased sensitivity
-	Resistance has not yet been observed
Much more effective, but slow absorption (50%), Ø bathing within 48h
Cats, rabbits Ø
-	Can lead to stronger systemic effects
Dogs 3-10x overdose
Prac-tic is used as a spot on
44
Q

indoxacarb (activyl)

  • MoA
  • resistance
  • metbolism
A

Sodium channel blocker hyperpolarization  paralysis of parasite
Also used in agriculture resistance, efficacy is not so high (decreased sensitivity?)
Prodrug  bioactive metabolite (selective toxicity) cleavage of 2 methoxy group effective flea control (adult, larva, egg!)

45
Q

indoxacarb - spectrum

A

Only against flea
Feeding and oviposition stops within 0-4 hours
Death within 4-48 hours (not very quick)
Flea allergy dermatitis (FAD) – good agent against it

46
Q

indoxacarb - application + safety

A

Spot on – not give to cat
Safe usage – prodrug and is activated inside the parasite
Environmentally safe

47
Q

neonicotinoid insecticides - MoA

A

ACH agonist -> depolarization -> excitation

48
Q

neonicotinoid - selective toxicity

A

560x affinity to nACh receptors of parasites
acts fast

environmental toxicity

49
Q

neonicotinoid - generations

A

Only 1st and 3rd generation is used:
imidacloprid (Advantage family, Foresto)1st gen. – spot on – very toxic for environment, cannot be used
anymore, kills the bees
dinotefuran (Vectra) 3rd gen. – pour on, lower dose needed, no resistance yet, more toxic for environment (honey bees)
nitenpyram (Capstar) 1st gen. – tablet

50
Q

DINETEFURAN+PERMETHRIN+ PYRIPROXYFEN (VECTRA 3D SPOT ON A.U.V)

A 
Cats and dogs
Fleas only 
Permethrin against tics (not in the ones for cat as it is dangerous in spot on)
Pyriproxyfen:  Larvae, puba, and eggs
   Doesn’t kill the adult flea
51
Q

imidacloprid

  • drug names
  • effective agaisnt?
  • environemntal issues?
  • safety?
  • application
A

Advantage, Advantix, advocate, forest A.U.V
One of the most effective agents against fleas, rapid action (within 6 hours >95%) – flea dermatitis too
Fleas, for 4 weeks
Epithelial debris! – when it goes to the environment it can kill the dust host mite – allergy condition
5-20x overdose is still safe (tremors, seizures?)
Collar(delayed duration of action, several months), spot on
+ permethrin (Advantix) – dont put in cat
+ flumethrin (Foresto) – impregnated collar, releases drug slowly – can be put on a cat
+ moxidectin (Advocate) – macrolides (amoxidectin)
Take care of the empty boxes – honey bees

52
Q

isoxazolines

  • drug names
  • MoA
  • safety
  • negative effects?
A

Oral antiparasitic drugs originally also as spot on now
Fluralaner (Bravecto®)
Afoxolaner (Nexgard®)
Sarolaner (Simparica®)
Lotilaner (Credelio®)
– GABA-antagonist, glutamate-gated Cl-channel antagonist
Overdose: excitation, tremor (unfrequent with overdoses, very expensive)
Plan for using it in humans against malaria and other mosquito born disease
Drawbacks of spot on’s/collars
– contact dermatitis
– bathing/washing off/getting wet
– usually does not cover the whole body
– small dogs are very sensitive – contact dermatitis

53
Q

efficacy of isoxazolines

A

Fleas + ticks
Fleas within 8 hours will be killed
Ticks within 12 hours (Lyme, Babesia)
No repellent effect, enough to prevent to get the lyme and babesia from the tics – it needs one day or 1 and half day to inject the disease
Mange mites – very good, due to the prolonged effect
Demodex spp. – really good, first choice
Poultry: Dermanyssus gallinae (fluralaner)
Used in large animals too – not sheep or cattle
Mainly small animals

54
Q

combinations of isoxazolines used in small animal medicine

A

Sarolaner + selamectin – stronghold plus

Afoxolaner + milbemycin – nexgard spectra

55
Q

pharmacokinetics of isoxazolines

A

Oral absorption: tmax 1 day
Feeding (2,1-2,5x) fluralaner ↔ sarolaner, afoxolaner
High plasma protein binding – binding to albumin
Slow metabolism
Enterohepatic circulation – when it is excreted into the bile from the GI will be reabsorbed (fluralaner + longer duration)
Accumulation in adipose tissues – it will increase the duration of action, elimination from fatty tissue takes time – goes to the blood circulation after

56
Q

half-life and side effects of isoxazolines

A

long half-life (10-15 days) -due to the slow metabolsim and high plasma binding
side effect: vomiting, if the drug is not given with feed (fluralaner also increased absorption)

57
Q

pharmacokinetic differences of isoxazolines

A

Afoxolaner: also excreted by kidneys (avoid with kidney patients)
Fluralaner (0,01%), sarolaner: almost entirely via bile
Enterohepatic circulation: fluralaner

58
Q

toxicity of isoxazolines

A

Large differences between LD50 and therapeutic doses
Sarolaner: 1x, 3x, 5x doses, 8 weeks old puppies
- 3x overdose: tremors, ataxia (12 mg/kg)
- 5x overdose: seizures, tremors, ataxia (20 mg/kg
GABA-antagonism! – resolves within 24 hours
Overdose: excitation

59
Q

insect growth regulators

A

It will not kill the adults, it will influence the other stages of the life cycle: egg laying, stop the eggs from hatching, larvae cannot become pupa and pupa cannot become adult
It will only act against insects that develop with metamorphosis so not against tics and mites

60
Q

juvenile hormone analogues

A

Methoprene (Frontline Combo®)
Pyriproxyfen (Duowin®, Vectra 3D®)  acts for even 48 days
Ø adulticide effect!
Inhibition of larval development (through eggs, pupas, and also with digested blood - Adult faceas and directly)
Deformity of mature forms, if they survive – no wing development
Light, residual activity: pyriproxyfen > methoprene

61
Q

chitin synthesis inhibitors

A

(mainly in agriculture)
lufenuron (Program®) – previously used (tabl)
novaluron
not used in veterinary practice

Pharma midterm 2 ectoparasiticides (1 decks)

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