Title: Antiparasitics
1Antiparasitics
Dr. Dipa Brahmbhatt VMD MpHdbrahmbh_at_yahoo.com
2Objectives
- Terminology antiparasitics
- MOA antiparasitics
- Precautions of antiparisitics
3Heartworm Prevention and Treatment
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5Treatment of Heartworm Disease
- Heartworm disease is caused by the filarial
nematode Dirofilaria immitis - Three stages of management of heartworm disease
- Adulticide therapy
- Microfilaricides Eradication of circulating
microfilariae after infection - Preventing third-stage larvae from reaching
maturity (preventative)
6Treatment of Heartworm Disease
- Adulticide therapy
- Melarsomine - Immiticide 1996
- Given in the epaxial muscles BETWEEN L3 L5
- Arsenic compound
- Less toxic than former drug (Caparsolate -
thiacetarsamide) - SE include coughing, gagging, and lethargy,
pulmonary congestion, localized inflammation
thromboembolism (fragments of worms) swelling and
pain - Nephrotoxicity and hepatotoxicity have been
reported. - Class 3 fatigue, dyspnea, right heart changes in
radiograph, RHF slow kill - Class 4 Not recommended for animals with caval
syndrome (large numbers of adult heartworms in
the right ventricle, right atrium, and vena
cava).
7- Heartworm Treatment Slow Kill Method VTI
- Team Dr. B, Dr. Dev, Miss Kennar, Miss Foitnik
- Doxycycline 5 10 mg/ kg (SID or BID)
- Prednisone 1 mg/kg BID X 7 days SID X 7 days,
EOD X 7 days - DAY 1
- Buprenex 0.015 mg/ kg OR Tramadol 1mg/lb BID X
3 days PO before melarsomine injection - Famotidine 0.5 mg/kg SQ before melarsomine
injection - Melarsormine 0.1 mls/ kg IM
- DAY 30
- Buprenex 0.015 mg/ kg OR Tramadol 1mg/lb BID X
3 days PO before melarsomine injection - Famotidine 0.5 mg/kg SQ before melarsomine
injection - Melarsormine 0.1 mls/ kg IM
- DAY 31
- Buprenex 0.015 mg/ kg OR Tramadol 1mg/lb BID X
3 days PO before melarsomine injection - Famotidine 0.5 mg/kg SQ before melarsomine
injection - Melarsormine 0.1 mls/ kg IM
8Dogs lt 22 lb. 1 inch needle 23G Dogs gt 22 lb.
1.5 inch 22G
9Treatment of Heartworm Disease
- Adulticide therapy
- LEVAMISOLE
- Not effective Kills few adult heartworms
- and neurological SE
- May be used as inexpensive treatment for reducing
adult burden and clearing mff. from blood - Ivermectin and Seleamectin has been shown to
reduce adult burden when used over time - After adulticide treatment After 1-2 weeks 0r
4-6 weeks - Worm emboli gt pulmonary inflammation coughing,
fever, /- bloody cough (hemoptysis) - Cage rest, glucocorticoids, aspirin?? (not if
hemoptysis) - Adulticide tx. Not recommended in cats
10Treatment of Heartworm Disease
- MICROFILARICIDES
- Ivermectin (most common) 0.05 mg/kg
- Given at higher dose as a microfilaricide
- Monitor for neurologic side effects, anaphylactic
shock - Should kill microfilaria in 3 weeks (monitor)
- 1 ivomec 0.1 ml/ 20kg or dilute 110 and 1ml/
20kg - Milbemycin oxime (interceptor/ sentinel/
trifexis) - 0.5mg/kg. Use with caution in HW dogs
Anaphylactic shock - Levamisole (infrequently used)
- Given for 1 week or longer depending on dosage.
- MOXIDECTIN IS NOT EFFECTIVE
11Treatment of Heartworm Disease
- PREVENTATIVES Preventing third-stage larvae from
reaching maturity - Daily oral preventative
- Diethylcarbamazine (DEC) Filaribits
- Given during mosquito season and two months after
- Anaphylactic shock and death can occur if given
to dog with microfilaria - Filaribits Plus also controls ascarid infections
(contains oxibendazole)
12Preventatives - Macrolide
- Ivermectin Heartgard, Iverhart PlusTM,
Tri-Heart PlusTM - 0.006 mg/kg (very low for collies)
- Macrocyclic lactones
- Plus products also contain pyrantel pamoate
(hooks, rounds) - Ages 6 months
- Side effects include neurologic signs such as
salivation, ataxia, and depression - Milbemycin oxime - Interceptor
- Sentinel milbemycin oxime lufenuron
- Also effective against hookworms, roundworms, and
whipworms and Demodex mites in dogs.
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15Monthly Topical Preventatives
- Selamectin - Revolution
- Absorbed systemically
- Dogs heartworm, adult fleas, ticks, ear mites,
sarcoptic mange - Cats heartworm, adult fleas, ear mites,
roundworms, hookworms
16Monthly Topical Preventatives
- Moxidectin imidacloprid Advantage Multi,
Proheart 6 - Heartworm prevention, Flea control, Intestinal
parasite prevention - Children should not come in contact with
application site within 30 minutes of
administration - Do not use on sick, debilitated, or underweight
animals
17Parasite Preventatives in Dogs
18Parasite Preventatives in Cats
19Six-month Injectable Preventative
- Moxidectin - Proheart
- Side effects include neurologic and
gastrointestinal signs - Withdrawn from the market in September 2004 due
to increased reports of adverse side effects
including liver and bleeding abnormalities. - Reformulated and reintroduced in 2008.
- Owners must sign a special Informed Consent
form - Age gt 6 months - lt 7 years
- SE Anaphylaxis, V/D, lethargy,
- erythma, pruiritis, hyperthermia
- TX heartworm, Dilofilaria
- Dimmitis, Ancylostoma caninum,
- Uncinara stenocephalia
-
20Ectoparasite Treatment
21Ectoparasite Treatment
- Ectoparasites can be controlled using a variety
of different drugs in a variety of different
formulations - Sprays, Dips, Pour-on, Shampoos, Dusts or
powders, Foggers, Oral products, Spot-ons ,
Injectables - Parasites Flies, grubs, lice livestock, flies
(bots and maggots) horses, companion animals
fleas, ticks, mange mites - Diseases Zoonotic Lyme, bubonic plague, RMSF
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24Lifecycle Flea
25Ectoparasite Treatment
- Organophosphates and Carbamates
- Pyrethrins and Pyrethroids
- Amitraz
- Macrolides
- Imidacloprid
- Fipronil
- Nitenpyram
- Insect Growth Regulators
- Insect Repellents
26Review - ANS
- SNS Fight/Flight
- Epinephrine and norepinephrine
- Adnergic recoptors
- Alpha 1 blood vessels skin, GI
- Alpha 2 help regulate release of NE
- Beta 1 HEART
- Beta 2 SMOOTH MUSCLE blood vessels heart,
skeletal muscle arterioles, terminal bronchioles
- PNS
- Acetylcholine
- Cholinergic receptors
- Muscarinic inc. GI stimulation, slow HR, miosis,
- Nicotinic found both in PNS and SN
27Neurotransmitters and Receptors
- Smooth/Cardiac muscles may constrict or dilate in
response to epi/norepi - 1. a1- adrenergic receptors cause
vasoconstriction of skin, GI tract, and kidney
dont need to digest, make urine, or bleed
profusely - 2. ß1-adrenergic receptors - increase heart rate
and force of contraction - 3. ß2-adrenergic receptors - cause
bronchodilation (relaxation)
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29Organophosphates Carbamates
- MOA acetylcholinesterase inhibitor
- Decompose readily in environment used more in
agriculture - SLUDDE, bradycardia, and miosis (pinpoint
pupils) classic signs of muscarinic/ nicotinic
overstimulation - Delayed neurotoxicity syndrome has been reported
in people, cats, dogs, and livestock occurs 1-2
weeks - Metabolism OP toxic to myelin sheath gt HL ataxia
gt paralysis - Cattle weakness, depression, droopy ears, bloat
- TX Atropine (better for CNS X 10 dose of
pre-anesthetic), Pralidoxime reverse OP - human
pharmacies - Persian cats, sick cats, Whippets, Greyhounds,
and certain exotic breeds of cattle are sensitive
to Ops. - As a general rule, these insecticides should not
be used on animals recovering from surgery, sick
animals, pregnant animals, or animals considered
to be stressed.
30Organophosphates Carbamates
- Ach muscarinic receptors
- Toxicity
- SLUDDE and miosis
- Tx
- X10 dose of atropine (better for CNS than
glycopyrrolate) - Pralidoxime separates OP molecule from
Ach-esterase
- Ach nicotinic receptors
- Toxicity
- Progressive initially-tremors gt progress to
shaking gt ataxia gt paralysis gt resp. failure
31Glycopyrrolate (Robinul) and Atropine
Use Glycopyrrolate in Pregnant animals it does
not appreciably cross CNS or placenta
Atropine comes in Two concentration 0.5 mg/mL
(injectable-SA) and 2.0 mg/mL (injectable-LA)
32Organophosphates Carbamates
- Adams Flea and Tick Dip, Spray, and Tick Dust
- Carbaryl (Mycodex shampoo with carbaryl)
- Sevin Dust
- Cythioate (Proban tablets and liquid)
- Diazinon (Escort)
- Phosmet (Paramite dip)
33Pyrethrins and Pyrethroids
- Pyrethrins are natural plant products, derived
from chrysanthemum flowers - Largest group OTC, very safe, quick kill
- Pyrethroids are synthetic pyrethrins better at
killing, -thrin suffix - Resmethrin degraded by UV, leaves odor like
stale urine - Fenvalerate and permethrin adhere to nylon/
carpets reduces efficacy - Permethrin and deltamethrin Tick collars flea
and ticks - allethrin, tetramethrin, deltamethrin,
cyfluthrin,
34Pyrethrins and Pyrethroids
- MOA Acts on parasites nerve cell
- membrane to disrupt sodium channel, which delays
polarization and paralyzes the parasite - SE cats sensitive and can show neurological
signs seizures/paralysis, poison fish - Synergists added piperonyl butoxide generally
safe, neurotoxicity cats. Also add insect
growth regulators (IGR) - Often manufactured with other products such as
imidacloprid pyrethrin(Advantx not for cats)
and as - synergist piperonyl butoxide
- K9 Advantix, Bio-Spot for dogs
35Formamidines Amitraz
- One of the first effective agents available for
demodectic mange in dogs. Can repel ticks. - MOA alpha 2 receptor agonist, adnergic (xylazine
and detomidine) gt decreases norepinephrine gt
sedation. Inhibits monoamine oxidase hence dont
use with behavior modifying drugs - Toxic to cats and rabbits, Use protective
clothing and gloves for humans keep it away from
children use in a well-ventilated area - SE Animals may show sedation and incoordination
for 24-48 hours after application, pruritus,
hypothermia
36Amitraz
- Can be very toxic if ingested by animals or
people - Reports of toxicity from ingestion of collars
- Treated with supportive therapy and multiple
doses of alpha-2 receptor antagonists Yohimbine
(Yobine) or Atipamezole (Antisedan), Tolazoline
(Priscoline, Tolazine)
37Amitraz
- ProMeris for dogs (synergistic with
metaflumizone) - Mitaban Dip
- PrevenTIC collar with
- IGR for fleas pyriproxyfen
- (Nylar)
- TakticEC (cattle)
Available in collars, topical treatment, dip, or
sponge-on bath.
38MACROLIDES
- Milbemycin oxime
- 2002 otic prep. In cats MilbeMite Otedectes
cynotis - Selamectin (Revolution) topical
- Dogs and cats fleas, ear mites, hwp
- Dogs sarcoptes mange, tick
- Extra label use exotics and wildlife
39Imidacloprid
- Advantage (imidacloprid fleas) and K9 Advantx
( permethrin tick and mosquito, dont use in
cats) - Chloronicotinyl nitroguanidine
- MOA Insect neurotoxin blocks receptor site for
Ach-nicotinic, thereby blocking transmission of
the impulse across the synapse. - Marketed for use in both dogs and cats fleas
- Poorly absorbed through skin and kills adult
fleas on contact - Wide margin of safety (toxicity in fish is low)
- Four week residual activity, topical back of neck
40Fipronil
- Frontline
- Fipronil with methoprene (Frontline plus)
- MOA Interferes with GABA receptors - chloride
channels of insects (less chloride in neuron),
which overstimulates their nervous system causing
death - Safe for mammals because has low affinity for our
GABA receptors - Adult fleas, ticks, and chewing lice (on
contact) controls sarcoptic mange with repeated
treatments. - Methoprene is an insect growth regulator, which
makes Frontline plus effective against flea eggs
and larvae. - Applied topically (absorbed in sebaceous glands)
not absorbed systemically - Residual activity, even after bathing
- Not for use in puppies or kittens lt8 weeks of
age.
41Fipronil
- Also marketed as a measured-dose spray product
that is applied at a dose of 3 ml/kg body weight. - Container is calibrated to administer precise
amount of insecticide to allow accurate dosing. - Manufacturer claims that fipronil is unlikely to
produce toxicity even if consumed orally. - Fipronil binds with the dermis, hair follicles,
and sebaceous glands. - Has alcohol salivation if licked and has
unpleasant order
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43Nitenpyram
- Capstar
- MOA Binds and inhibits Ach-nicotinic receptors
- Safe for mammals low affinity for receptor (safer
than OP) - Tablet begins to kill adult fleas within 30
minutes - At least 90 fleas killed in 4 hrs. (dogs) 6
hrs. (cats) - Can safely give a dose as often as one per day
- Can use on puppies and kittens older than 4 weeks
and weighing more than 2 lb. - Only kills adult fleas should also give insect
growth regulator (IGR) to control fleas. - SE intense pruritus for short period THIS IS OK
44Lindane
- The only chlorinated hydrocarbon currently
- used in veterinary medicine today.
- Incorporated in some dog shampoos.
- Kills insects on contact directly absorbed into
insects and their eggs also a stomach poison for
insects - Can produce harmful side effects in people and
pets if absorbed in sufficient quantities. - Owners should wear gloves, apron, boots
- Dispose of empty bottles and bath water according
to EPA policies - Lindane should never be used on cats, puppies lt3
weeks, lactating animals, or food animals.
45Newer products
- Spinosad (thanks bacteria) Bad taste
- Comfortis and Trifexxis
- MOA nerve paralysis of fleas at nicotinic Ach
receptors and also GABA - Kills adult fleas 100 - 4 hrs
- FAD
- SE vomiting
- To avoid split dose BID
46Insect Growth Regulators
- Insect growth regulators are compounds that
affect immature stages of insects and prevent
maturation to adults. - Include Insect development inhibitors (IDI) and
juvenile hormone mimics (JHM) - Insect development inhibitors interfere with
development of chitin, which is essential for
proper egg formation and development of the
larval exoskeleton. The egg-tooth used by flea
larvae to exit egg is also made of chitin.
47Insect Growth Regulators
- Juvenile hormone mimics prevent fleas from
molting to the next stage by interrupting normal
molting process. (Fleas need low levels of JH to
molt to the next stage these products mimic the
fleas natural JH) The insect stays in the larval
stage and eventually dies. - Insect growth regulators do not affect adult
fleas. - Lufenuron (PROGRAM), methoprene, fenoxycarb, and
pyriproxyfen are all IGRs.
48Lufenuron
- Program Insect Development Inhibitor
- The flea component in Sentinel
- Interferes with chitin synthesis in flea
development - Given orally to dogs orally or SQ to cats lasts
for 6 months - Fleas must bite the animal to be exposed to the
drug. - Effects are noted in 2 weeks hence use with
adulticide - Also investigated to use for ringworm
- Lufenuron is distributed to fat and then leaches
slowly back into the body fluids, providing a
long duration of activity therefore drug needs
to be given only once monthly. - SE vomiting, listlessness
49Other IGRs
- Methoprene (Ovitrol) is generally regarded as
safe. It is found (sometimes as Precor) in
sprays, topical products, and flea collars. - Female flea absorbs compounds from skin of animal
(deposited by flea collar) and it is incorporated
into eggs - Flea pupae in carpet are protected from
methoprene because it binds to fibers in carpet. - FRONTLINE plus with fipronil
- Pyriproxyfen (Nylar) JHM - Mostly used in
environmental flea control products may have
some activity against adult fleas (but not
immediate) more potent than methoprene and
fenoxycarb - Fenoxycarb was voluntarily withdrawn from the
market by the manufacturer in 1996 because of
concerns over the results of government testing
involving the use of high doses. It breaks down
to formaldehyde, a carcinogen.
50Insect Repellents
- Used to repel insects and keep them off of
animals - Livestock, horses, outdoor dogs upright ears
German Shepherds and Dobermans - May be used in combination with pyrethrins and
pyrethroids - Include sprays, ear tags, and topicals for ear
tips - Some products are insecticides as well as
repellents - Control mosquitoes, flies, and gnats.
- DEET Diethyltolamide (Blockade - Hartz)
Combination with fenvalerate was withdrawn from
market for several months because of reports that
it caused death in several cats and dogs. - Signs of DEET toxicosis include excitation,
tremors, seizures, ataxia, and vomiting.
51Insect Repellents
- Butoxypropylene glycol (Butox PPG or VIP Fly
Repellent) - Used in equine fly repellents because it provides
a shine that is of cosmetic value in show animals - Incorporated into flea and tick spray products
for use in dogs and cats - Can cause dermal irritation if a harness or
collar is applied over the area while the
haircoat is still wet with spray.
52Other External Antiparasitics
- Rotenone - A.k.a. Derris Powder (derived from
derris root) - Ear Miticide, Mitaplex-R
- Used in dips and pour-on liquids
- Toxic to fish and swine consider runoff
possibilities when using. - D-limonene (VIP Flea Dip and Shampoo)
- Derived from citrus peels
- Has slight insecticidal activity
- Pleasant smell provides quick kill may be used
with other products
53References
- Romich, J.A. Pharmacology for Veterinary
Technicians, 2nd edition. 2010. - Bill, R.L. Clinical Pharmacology and Therapeutics
for the Veterinary Technician, 3rd edition. 2006. - Beale, Karin. Favorite New Treatment Options in
Veterinary Dermatology. Gulf coast veterinary
specialists symposium, 2012. - http//en.wikipedia.org/wiki/FileAdrenoceptor-Sig
nal_transduktion.PNG