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Pharmacology 2 > Antihelminthics > Flashcards

Antihelminthics Flashcards

1
Q

Combinations

  • Horse
A
  • Ivermectin + Praziquantel (oral paste)
  • Abamectin + Praziquantel (oral paste)
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2
Q

Benzimidazoles and Probenzimidazoles

  • side effects
A

PO relatively safe, on-toxic agents (TI > 20)

  • Teratogenicity (Oxf., Alb., Feba.,)
  • Hepatotoxicity, hair lss, feather loss
  • Neurotoxicity
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3
Q

Benzimidazoles and Probenzimidazoles

  • Application in Ruminants
A

(Netob., Alb., Ricob., Feban., Fenb., Ofx., Triclab.)

  • Meb., not in cattle
  • the antihelmithic activity is greater in sheep than cattle
  • dose rates in cattle are higher than sheep
  • Special drug delivery systems: only sheep and cattle
  • Pulse-relase bolus, Oxfendazole, released approx. each 3 week in rumen
  • Sustained-release puls, Fenbedazole, release profile of 140d
  • Slow-release capsule, Albendazole, release profile 105d
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4
Q

Tetrahydropyrimidines

  • mechansim of action
A
  • cholinomimetic activity, ganglion stimulant, interaction with parasitic nerve transmission, leading to spastic paralysis.
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5
Q

Other endoparasiticides:

  • Clorsulon
A

(aminobenzene disulphonamide derivative)

  • anti liver-fluke preparation
  • inhibits enzymes of the glycolytic pathway in liver flukes (cellular energu production is disrupted)
  • in plasma is bounded to proteins
  • safety margin is wide (TI=20)
  • not licensed for use in lactating dairy cows
  • Sheep PO suspension for infections with (mainly) adult liver flukes
  • Cattle SC injection in combination with Ivermectin
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6
Q

Salicylanilides and Substituted phenols

  • Anthelmintic spectrum
A
  • Used in sheep and cattle againts Fasciolosis and Haemonchosis (hematophagous nematodes, e.g. Haemonchus and Brunostomum)
  • Low efficacy agaist immature flukes, due to high protein binding of these drugs in the blood.
  • active against 6 week old flukes in cattle and sheep
  • Diamphenetide has high activity against the youngest immature stages
  • generally ineffective against nematodes (due to lack of drug uptake)
  • Some antinematodal activity: e.g. Closantel, Disophenol, Nitroscanate
  • Active aganst tapeworm (AC): Nitroscanate, Dichlorophen and Nicliosamide
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7
Q

Other endoparasiticides:

  • Bunamidine
A

(salts)

  • anticestodal naphtamidine compounds
  • used in small animals, leads to digestion of tapeworms in the gut of the host, due to inhibition of glucose uptake of worms
  • most effective if given after fasting
  • it is absorbed and metabolized in the liver
  • vomiting and mild diarrhea may be seen, and exercise or excitment should be avoided in gods soon after administration, because it can give acute heart failure
  • Rarely used
  • Prohibited in food-producing animals
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8
Q

Imidazothiazoles

  • mechanism of action
A
  • as agonists at nicotinic acethylcholine receptors of nematodes, they are ganglion-stimulants (cholinomimetic)
  • they stimulate ganglion-like structures in somatic muscle cells of nematodes.
  • this stimulation first results in sustained muscle conractions, followed by a neuromuscular depolarizing blodckage resulting in spasmic paralysis
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9
Q

Macrocyclic Lactones (Macrolides)

  • Anthelmintic spectrum
A
  • adult, immature nematodes, including hypobiotic larvae, microfilariae and arthropods
  • resistance may occur (parallel with BZs and Levimasole
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10
Q

Benzimidazoles and Probenzimidazoles

  • resistance
A

Ruminants: GI-roundworms

Swine: oesophagostomum spp.

Horse: large strongyles

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11
Q

Salicylanilides and Substituted phenols

  • substances
A

Salicylanilides:

  • Brotianide, Clioxanide, Clostantel (AN), Niclosamide (AC, off label), Oxyclozanide (AT), Rafoxanide (AT)

Substituted phenols:

  • Bithionol, Disophenol (AN), Dichlorophene (AC, off label), Hexachlorophene, Niclofolan, Menichlofolan, Nitroxinil and Diamphenethilde (is an aromatic amide), Nitroscanate (AC, AN, only in dogs, off label)
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12
Q

Benzimidazoles and Probenzimidazoles

  • Application in Swine
A

(Fenb., Flub.) (Oxib., Meb., off label)

  • agianst both adult and immature stages of Ascaris Suum and other swine nematodes
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13
Q

Tetrahydropyrimidines

  • side effects
A
  • cholinergic type of signs.
  • antidote: atropine
  • Morantel in Ru tends to be safer and more effective than Pyrantel
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14
Q

Other endoparasiticides:

  • Emodepside, mechanism of action
A

is synthesised by attaching a morpholine ring to a metabolite of Mycelia sterile

  • inhibitory effect on synaptic transmission, by binding to a group of G-protein coupled receptors called Iatrophilins. This activates the channel causing potassium ion efflux, hyperpolarization and subsequent inhibition of excitatory neurotransmitter effect of acetylcholine, inhibiting muscle in the parasitic nematides (flaccid paralysis) and inhibiting locomotove and pharyngeal pumping functions, furthermore inhibiting egg laying.
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15
Q

Other endoparasiticides:

  • Amino-acetonitrile derivatives, monepantel
A

Mechanism of action:

  • agonist on nicotinic receptors of worms (Hco-MPTL-1 unit - no cross-resistance exists)

Spectrum:

  • relatively narrow, GI nematodes (including hypobiotic larvae) No AC, No AT.

Resistance:

  • originally active against nematodes that are resistant to other anthelmintics

Pharmacokinetics:

  • absorption from GI is good.
  • Rapid metabolization to sulfoxide and sulfone metabolites.
  • Excretion with feces, via bile, Cmax 24 hr, T 1/2: 5days.

Side effects:

  • 10 times overdosing is well tolerated by sheep, ONLY
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16
Q

Combinations

  • Dogs
A
  • Fenbantel + Praziguantel + pyrantel (PO tabl.)
  • Praziquantel + Emodepside (PO tabl. spot on)
  • Emodepside + Toltrazuril (PO. sol.)
  • Fenbantel + Pyrantel (PO susp)
  • Fenbendazole + Praziquantel + Pyrantel (PO tabl)
  • Milbemycin oxime + Praziquantel (PO tabl)
  • Diclorophen + Piperazine (PO tabl)
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17
Q

Combinations

  • Cattle
A
  • Levamisole + Oxyclozanide (oral susp.)
  • Clorsulon + Ivermectin (SC)
  • Closantel + Ivermectin (SC)
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18
Q

Benzimidazoles and Probenzimidazoles

  • Application in Horse
A

(fenb. , Febant., Oxf.,) (Meb., Triclab is off-label)
- high levels and repeated administration for extraintestinal migrating stages of large strongyles (widepsread resistance)

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19
Q

Salicylanilides and Substituted phenols

  • side effects
A

General uncouplers of axidative phosphorylation, their TI are lower (4-8) than those of many other anthelmintic agents. Relatively toxic

  • recommended dosages: mild anemia and unformed faeces
  • high dosages: blindness, hyperthermia, onvulsions, coma and death. = classic signs of uncoupled phosphorylation
  • Adverse effects are most commonly seen in animals that are stressed, in poor condition nutritionally or metabolically (cachexia) or that have severe parasitic infections
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20
Q

Piperazines

  • substances
A
  • Piperazine (phosphate, adipate, citrate)
  • Diethylcarbamazine (citrate)
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21
Q

Macrocyclic Lactones (Macrolides)

  • substances
A
  • they are potent ectoparasiticdes as well - called as endectocides

Avermectins:

  • Abamectin, Doramectin, Eprinomectin, Ivermectin, Selamectin

Milbemycins:

  • Moxidectin and Milbemycin oxime
22
Q

Benzimidazoles and Probenzimidazoles

  • other effects
A
  • Antitumor, antifungal/fungicide, antiviral, ion-pump inhibition (omeprazol), antiparasitic effect (giardia, ear mite)
23
Q

Piperazines

  • anthelmintic spectrum
A
  • Piperazines:
  • largely against Ascarid parasites in all animal species. Large doses against hookworms
  • Diethylcarbamazine:
  • heartworm prevention in dogs.
  • treatment of prepatent Dictycocaulus viviparus infections (lungworm infection) in cattle. (relatively ineffective against the adult worms)
24
Q

Tetrahydropyrimidines

  • pharmacokinetics
A

Pyrantel tartrate (or citrate)

  • is well absorbed by pigs and dogs, less well by ruminants
  • the pamoate salt is poorly soluble in water; reduced absorption from the gut and allows the drug to reach and be effective against parasites in the large intestines. Which makes it usefull for horse, cats and dogs
  • metabolism of pyrantel is rapid, excreted rapidly in the urine, some unchanged drug is excreted in the faeces.

Morantel

  • is absorbed rapidly from the upper small intestine of the sheep and metabolized rapidly in the liver; 17& is excreted in the urine.
25
Q

Imidazothiazoles

  • side effects
A
  • cats, horses and certain dog breeds (e.g Kuvasz) are very sensitive, birds and reptiles more tolerant
  • toxic signs are: cholinergic-type signs of salivation, muscle tremors, ataxia, urination, defecation and collapse, asphyxia due to resp. failure.
  • Antidoe: atropie
  • some infl. on site of SC injection
26
Q

Imidazothiazoles

  • application
A
  • normally PO (all species) or SC (sheep)
  • topical prepartions (pour on) for cattle
27
Q

Macrocyclic Lactones (Macrolides)

  • Mechanism of action
A
  • potentiation of inhibitory transmitters by binding to glutamate - and GABA-gated (eaker) chloride channel receptors in nematode and arthropod nerve cells
  • this cause the channel to open, allowing influc of chloride ions
  • Macrocyclic lactones paralyze the pharynx, the body wall and the uterine muscle of nematodes
28
Q

Piperazines

  • application
A
  • Piperazine: PO
  • Dogs, cats, pigeon 120 (240 hookworm) mg/kg BW
  • Diethylcarbamazine: PO / IM
  • Cattle, IM
  • Dog: PO
29
Q

Benzimidazoles and Probenzimidazoles

  • application
A
  • BZs are sparingy soluble in water
  • They are given PO as a suspension, paste, bolus or premix (except Netobimin which can be injected)
  • Thiabendazole is applied topically (fungicide, earmites, larva migrans)
  • WP: 8-14 days for slaughtering of eat, 3-5 days for milking, longer for bolus formulations
30
Q

Tetrahydropyrimidines

  • substances
A
  • Pyrantel:
  • Citrate, tartrate salt: Cattle, horses, cats, dogs and pigs
  • Pamoate, Emboate salt: horses, dogs, cats
  • Morantel: the methyl ester analog of pyrantel
  • Ruminants
  • Oxantal: dogs (in combinations)
31
Q

Tetrahydropyrimidines

  • anthelmintic spectrum
A
  • antinematodal effect (relatively large spectrum against GI nematodes - they were first broad spectrum agents against these parasites)
  • adult gut worms and larval stages that dwell in the lumen or on the mucosal surface.
  • limited or no activity against migrating larvae, and Trichuris spp. (whipworms), except Oxantel.
  • nematodes resistant to levamisole are cross-resistant to Morantel due to the similarities of their mechanism of action.
  • except: Horses Anoplocephala perfoliata (tapeworm/cestode)
32
Q

Tetrahydropyrimidines

  • application
A
  • Pyrantel pamoate: Horse, dogs and cats PO paste (+ in combination with tablets)
  • Morantel: Cattle slow release ruminal bolus, sheep oral suspension.
33
Q

Imidazothiazoles

  • anthelmintic spectrum
A
  • Antinematodal: Heartworm - D.immitis, larvacidal
  • resistance to Levamisole for GI nematodes of cattle and sheep
  • Nematodes resitant to levamisole are cross-resistant to Morantel (similar mechanism of action)
  • immunostimulant effects
34
Q

Imidazothiazoles

  • substances
A
  • Tetramisole, a racemix mixture (less safe, recently not used)
  • Levimasole, L-isomer form (anthelmintic)
35
Q

Salicylanilides and Substituted phenols

  • mechanism of action
A
  • uncoupling of oxidative phosphorylation processes. These compounds act as protonophores, allowing hydrogen ions to leak through the inner mitochondrial membrane
36
Q

Piperazines

  • side effects
A
  • The safity margis is limited (less in horse, puppies, kittens)
  • TI 3-10
  • Toxic sign caused by large doses including: vomitting, diarrhea and ataxia + CNS signs.
37
Q

Piperazines

  • mechanism of action
A
  • Block neuromuscular transmission (GABA agonistic effect) in the parasite by hyperpolarizing the nerve membrane, which leads to flaccid paralysis (reversible vermifugal effect, without killing them)
  • also block succinate production in the worm.
  • The parasites, paralyzed and depletet of energy, are expelled by peristalsis.
38
Q

Benzimidazoles and Probenzimidazoles

  • substances
A

1. Thiazolil benzimidazoles:

  • Thibendazole, Cambendazole

2. Benzimidazole carbamates:

  • 5-keto BZs
  • Mebendazole, Oxibendazole
    • halogenated: Flubendazole, Triclabendazole
  • Sulphid BZs
  • Albendazole, Fenbendazole, Oxfendazole (Fenbendazole sulphoxide), Ricobendazole (Albendazole sulphoxide)
    • halogenated: Luxabendazole

3. Probenzimidazoles (Pro-drugs)

  • Febantel –> Fenbendazole –> oxfendazole
  • Netobimin –> Albendazole –> Ricobendazole
  • thiophanate –> Lobendazole
39
Q

Macrocyclic Lactones (Macrolides)

  • Application
A
  • SC inj. Ru, Swine
  • PO., Swine premix, Horse paste, Dog tablets
  • Dermal (pour on)
40
Q

Salicylanilides and Substituted phenols

  • application
A

All are given PO, except Nitroxinil which is given SC.

  • Closantel: Cattle, sheep
  • Nicosamide: sheep, dog, cat, bird, fish
  • Dichlorophene: dog, cat
  • Nitrocinil: cattle, sheep, pheasant (syngamosis)
  • Diamphenethide: sheep
  • Nitroscanate: dog
41
Q

Combinations

  • Sheep
A
  • Ivermectin + Triclabendazole (oral susp)
  • Levamisole + Oxyclozanide (oral susp)
  • Closantel + Ivermectin (SC)
  • Closantel + Mebendazole (oral susp.)
42
Q

Benzimidazoles and Probenzimidazoles

  • mechanism of effect:
A

Primary effect:

  • inhibition of tubulin polymerization: by binding to the colchicine-sensitive site of tubulin, thus inhibiting its polymerization or assembly into microtubules, leading to degerative alterations in the tegument and intestinal cells of the worm.

Secondary effect:

  • inhibition of cellular transport and energy metabolism, are consequences of the depolyemerization of microtubules.
  • Vermicidal
  • les mer i ppt.
43
Q

Macrocyclic Lactones (Macrolides)

  • Side effects
A
  • TI=10 moderate-wide
  • Abamectin and Moxidectin are contraindicated in calves and foals less than 4 months old
  • Mammalian safety depeds on P-glycoprotein activity in the BBB.
  • CNS depression in cattle breeds (Murray Grey) and Collies
  • Nervous signs including depression, muscle weakness, blindness, coma, death, especially in Collies
44
Q

Benzimidazoles and Probenzimidazoles

  • Deworing effect - antihelmitic spectrum
A

Antinematodal effect (AN):

  • broad spectrum of activity against roundworms (nematodes)
  • Larvicidal and ovicidal (Alb., Fenb., Feban., Oxf., Oxib.)

Anticestodal effect (AC)

  • Febantel, Fenbendazole, Netobimin, Albendazole, Ricoendazole, Mebendazole, Oxfendazole, Flubendazole, Luxbendazole

Antitrematodal effect (AT)

  • (for flukes, Fasciola, Dicrocoelium. Paramphistomum spp.)
  • Netobimin, Albendazole (only against older larval and adult stages of liver fluke + other flukes)
  • Triclabendazole - only liver fluke (both immature and adult flukes)
45
Q

Piperazines

  • pharmacokinetic features
A
  • rapidly absorbed from the GI tract
  • excretion via kidneys. Piperazines can be detected in the urine as early as 30 min. after administration (residues in eggs)
  • the excretion rate is maximal at 1-8 hr, and excretion is practically complete within 24 hr (therefore everyday treatment is necessary).
46
Q

Benzimidazoles and Probenzimidazoles

  • Application in Dogs and Cats, birds and poultry
A

Dog and cat:

(Febant., Fenb., Flub., Meb., Oxib.)

  • treatment of roundworms, hookworms and tapeworms. BID for 3 days

Birds and Poultry:

(Flub.) (Fenb., Meb off label)

  • against GI and respiratory nematodes
47
Q

Other endoparasiticides:

  • Emodepside, therapeutic use
A
  • is effective against a number of GI nematides, roundworms, hookworms
  • Licensed for use in combination with Praziquantel in cats for topical application (spot-on), in dogs for oral application (tablets), PROFENDER
  • With toltrazuril for puppies
48
Q

Other endoparasiticides:

  • Melarsomine
A

organic arsenical compound

mechanism of action:

  • adulticide (only active against adult heartworm), microfilarias are not sensitive
  • alterations in glucose uptake and metabolism, inhibition of gluthatione reductase

Pharmacokinetics:

  • good tissue distribution, crosses BBB. Half-life in dog 3hr. Incomplete metabolism in liver, excretion in urine and bile.

Side effects:

  • low therapeutc index
  • 3x overdose: serious pulmonary edema - lethal.
  • Slight overdose: serious GI symptoms (emesis, diarrhea), bradycardia, tremor and severe depression.

Application:

  • IM
  • deep into the lumbar (epaxial) muscles of the third to fifth lumbar vertebral region (L3-L5)
49
Q

Other endoparasiticides:

  • Emodepside, side effects
A
  • Relatively non-toxic
  • adverse reaction are rare: licking, excessive grooming, scratching treatment site, salivation, lethargy, alopecia, agitation/nervousness, vomiting, diarrhea, eye and respiratory irritation, and shaking/tremors)
  • all adverse effects are self-imiting (will disappear after termination of application).
50
Q

Combinations

  • Cats
A
  • Praziquntel + Pyrantel (PO tabl)
  • Praziquantel + Emodepside (spot on)
  • Milbemycin oxime + Praziquantel (PO tabl)
  • Dichlorophen + Piperazine (PO tabl)

Pharmacology 2 (13 decks)

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