Anthelminthics Flashcards
What does the MDR1 resistance gene code for and what drugs are affected by it?
P-glycoprotein which is an integral part of the BBB and is involved in active drug elimination in the liver and kidney and limits drug absorption in the gut
What breeds are most susceptible to MDR1 mutation?
Australian Shepherds, Border Collies, Shelties, Old English Sheep dogs
Breeds that have the MDR1 mutation should not be administered which drugs?
Macrocyclic lactones, vinca alkaloids, loperamide, paclitaxel, doxorubicin, cyclosporine, digoxin, diltiazem, losartan, morphine, butorphanol, fentanyl, steroids, erythromycin, rifampicin, ketoconazole, levofloxacin, cimetidine, acepromazine, amitryptiline, and domperidone
Macrocytic lactones
MOA: Macrocyclic lactones bind to glutamate receptors that trigger chloride influx, which hyperpolarizes the parasite neuron and prevents initiation or propagation of normal action potentials. The net effect is paralysis and death of the target parasite
Helminth activity: Only has an effect against adult GI worms, only on microfilaria of filarial worms
Formulations: Ivermectin, Eprinomectin, Moxidectin, Milbemycin, Selamectin
Fun facts: excreted in the feces unchanged; Half-life of ivermectin is 2 days, moxidectin is 19 days
Adverse effects: MDR1 mutation in certain breeds, common clinical signs: vomiting, ataxia, lethargy, tachycardia, hypersalivation, mydriasis, and seizures
Doramectin
Origin: Macrocytic lactone from the fermentation of Streptomyces avermitlis
Half-life: 4 days
MOA: bind to glutamate receptors that trigger chloride influx, which hyperpolarizes the parasite neuron and prevents initiation or propagation of normal action potentials
Activity:
- Cattle: GI roundworms, lungworms, eyeworms, grub, sucking lice, mange mites Injectable); pour-on can eliminate biting lice; extra-label: screwworms
- Swine: injectable- GI roundworms, lungworms, kidney worms, sucking lice, mange mites
- Dogs/cats: Off label for demodex
Adverse effects: Cattle: do not use 35-45 days from slaughter; swine do not use 24 days from slaughter
Examples: Dectomax
Eprinomectin
Origin: 2nd gen Macrocytic lactone from a fermentation product of Streptomyces avermitilis
MOA: bind to glutamate receptors that trigger chloride influx, which hyperpolarizes the parasite neuron and prevents initiation or propagation of normal action potentials
Activity:
- Cattle: Pour on- barber pole worms, brown stomach worms, small intestinal worms, bankrupt worms, Nematodirus, nodular worms, hookworms (Bunostomum phlebotomum) threadworms, lungworms, and whipworms. cattle grubs, sucking lice, biting lice, mange mites, horn flies. Injectable can inhibit some of the L4
- Sheep: Pour on- GI nematode, lungworms
- Donkey: Pour-on- Strongyles
- Rabbits: Extra label for ear mites (Psoroptes caniculi
- Cats: combined with praziqunatel
Adverse effects: Do not slaughter with 45 days of inj (cattle)
Examples: Eprinex (pour on), Longrange (inj.), Centragard (cats)
No withdrawal time in meat or milk with pour on
Ivermectin
Origin: Macrocytic lactone
MOA: bind to glutamate receptors that trigger chloride influx, which hyperpolarizes the parasite neuron and prevents initiation or propagation of normal action potentials.
Activity:
- Horse: large and small strongyles, pinworms, ascarid, large mouth stomach worms, bots, lungworms, threadworms, Habronema and Drashia larvae, and Oncocerca microfilariae
- Cattle: Inj.- GI roundworms, cattle grubs, lungworms, sucking lice, mange mites. Sq- prevents Dictocaulus, Oesophagostomum, common GI parasites. Off label: Parafilara bovicola and Thelazia rhosesi
- American bison and reindeer: FDA approved for grubs, and warbles (Hypoderma tarandi-Reindeer)
- Sheep: Drench-Adult and L4 H. contortus and adults only of H. placei. Stomach and GI intestinal worms, lungworms, nasal bots
- Goats: Intestinal parasites, extra label- sarcoptes
- Swine: Inj.-Adults and L4 of Ascaris suum, red stomach worms, nodular worms, threadworms, somatic larvae of Strongyloides, adult lungworms, sucking lice, mange mites. Extralabel- kidney worm
- Dogs: HW L3 & L4, ascarids, hookworms, threadworms; extra-label- demodex, sarcoptes, Cheletiella, Capillaria, eucoleus, Pneumonyssoides cannum (nasal mites)
- Cats: Ear mites, HWP, hookworms, roundworms. Extralabel- Aleurostrongylus abstrusus
Examples: Ivomec, Eqvalan paste, Heartgard
Milbemycin oxime
Origin: Macrocytic lactone that is a fermentation product of Streptomyces hygroscopicus subspp. aureolacrimosis
MOA: bind to glutamate receptors that trigger chloride influx, which hyperpolarizes the parasite neuron and prevents initiation or propagation of normal action potentials.
Activity:
- Dogs: Kills L3 and L4 HW and inhibit the release of L1, hookworms, roundworms, whipworms. Extralabel- resistant demodex, sarcoptes, nasal mites
- Cats: L3/L4 HW and ear mites, hookworms and roundworms
- Turtle: Extra label uses
Formulations:
Adverse effects:
Examples:
Moxidectin
Origin: Macrocytic lactone
MOA: bind to glutamate receptors that trigger chloride influx, which hyperpolarizes the parasite neuron and prevents initiation or propagation of normal action potentials.
Activity:
- Horses: larval and adult of large strongyles, adults and encysted of small strongyles, ascarids, pinworms, hairworms, stomach worms, botfly larvae
- Cattle: Gi roundworms, lungworms, mange mite (Psroptes), sucking lice
- Sheep and Goats: Gi rounds, extra-label inj. for lungworms
- Dogs: HW (L3/L4) and GI nematodes
Adverse effects: do not use in heavily parasitized thin horses, cattle under 8 weeks or lactating dairy
Examples: Quest, Cydectin
Pour on doe s not have a withdrawal time
Selemectin
Origin: Macrocytic lactone, modification of doramectin
MOA: bind to glutamate receptors that trigger chloride influx, which hyperpolarizes the parasite neuron and prevents initiation or propagation of normal action potentials.
Activity:
- Dogs and cats: HWP (L3/L4), fleas, ear mites, Sarcoptes, Dermacentor variables, feline hookworms, and roundworms. Europe- labeled for Lice. Extralabel for lungworms, canine nasal mites, cats with chiggers
Adverse effects: Can be used with MDR1 dogs
Examples: Revolution
Albendazole (helminths)
Origin: Benzimidazole
MOA: bind to tubulin molecules; this inhibits the formation of microtubules and disrupts cell division and may inhibit fumarate reductase which blocks mitochondrial function
Activity:
- Cattle: Oral- H. contortus and placei (larva and adults), brown stomach worm, small stomach worms, bankrupt worms, thread-necked worms intestinal worms, Cooperia, hookworms, nodular worms, tapeworms, and adult liver flukes (F. hepatica)
- Goats and sheep: F. hepatica (adults), tapeworms, fringed tapeworms (Thysanosoma actinoides), brown stomach worms, barber pole worms, small stomach worms, Cooper’s worms, bankrupt worms, nodular worms, large-mouth bowel worms (Chabertia ovina), and lung worms. Extra-label- Dicrocoelium dendriticum, lungworm
- Dogs/cats- NOT approved. Etxtra label for F. hirthi, Pearsonema plica, Paragonimus kellicoti
Adverse effects: Cannot be used in pregnant or lactating animals; 27 day withdrawal cattle, 7 days small ruminants. Aplastic anemia in dogs/cats
Examples: Zentel
Febantel
Origin: Benzimidazole prodrug (metabolized to fenbendazole and oxyfendazole
MOA: bind to tubulin molecules; this inhibits the formation of microtubules and disrupts cell division and may inhibit fumarate reductase which blocks mitochondrial function
Formulations: Always a combo drug
Fenbendazole (helminth)
Origin: Benzimidazole; metabolized to oxfendazole sulfoxide and oxfendazole sulfone
MOA: bind to tubulin molecules; this inhibits the formation of microtubules and disrupts cell division and may inhibit fumarate reductase which blocks mitochondrial function
Activity: Drug of choice for Giardia in pregnant animals
- Cattle: Lungworms, stomach worms, intestinal worms; In beef can increase the dose to cover tapeworms and inhibit L4 of Ostertagia
- Horses: Large strongyles, small strongyles, higher doses- ascarids, and L4 S. vulgaris (off label)
- Swine: Feed/water additive- lungworms, GI worms, kidney worms
- Dogs: Roundworms, hookworms, whipworms, and Taenia piriformis. Extralabel- Paragonimus kellicoti
- Cats: Not approved in USA. Ascarids, hookworms, whipworms, strongyloides, and Taenia sp. Possible Aluerostrongylus, Eusolus aerophilus, C. feliscati (bladder), Paragonimus kellicoti, Eurytrema procyonis (pancreatic fluke)
- Goats: Barber pole worm, brown stomach worm,
- Sheep: Not approved in USA, but used in Europe for cestode and GI and lung nematodes
- Bighorn sheep: approved for lungworms (Protostrongylus)
Examples: Panacur or Safe-Guard
Panacur is only drug in dogs proven to prevent vertical transmission
Oxfendazole (helminths)
Origin: Benzimidazole
MOA: bind to tubulin molecules; this inhibits the formation of microtubules and disrupts cell division and may inhibit fumarate reductase which blocks mitochondrial function
Activity:
- Cattle: Beef and non-lactating dairy cattle- lungworms, roundworms, tapeworms
- Dogs: Lungworms (Filaroides osleri)
Examples: Synanthic Bovine Dewormer
Oxibendazole (helminths)
Origin: Benzimidazole
MOA: bind to tubulin molecules; this inhibits the formation of microtubules and disrupts cell division and may inhibit fumarate reductase which blocks mitochondrial function
Activity:
- Horses: Large and small strongyles, Ascarids, Pinworms
Adverse effects: Do not use in debilitated horses
Examples: Anthelcide EQ,
