Antiparasitics

Antiparasitics… Make up the largest category of products available to veterinary professionals and the general public Can be OTC or Rx Help to protect animals from diseases, as well as people Is an important topic of client education for veterinary technicians (let them look under the microscope, show them a heart filled with worms) Is a quickly changing market

The ideal paraciticide is…. Selectively toxic to the parasite and not the host Does not induce resistance in the target parasite Is economical Effective against all parasite stages with one application Fragrant or odorless Environmentally safe

General rules of antiparasitics Use with caution in old, young, debilitated, or pregnant animals Certain antiparasitics are risky for certain groups of animals They are only effective if most of the drug reaches the location of the parasite The client and veterinary team must understand which part of the parasite’s life cycle is affected by the drug and how/ when the drug should be applied

Terms Endectocides: have the ability to kill endoparasites and ectoparasites Endoparasites cause infections, ectoparasites cause infestations Parasites in an abnormal location in a hosts body are aberrant Anthelmintics: kill helminth worms (parasitic worms) Vermicide: kills the worm Vermifuge: paralyzes the worm Antinematodals: treat round worms Anticestodals: treat tapeworms or segmented flat worms Antitrematodals: treat trematodes flukes/unsegmented flat worms Antiprotozoals: treat single-celled organisms: coccidian, giardia, Toxoplasma

DRUGS THAT TREAT ENDOPARASITES ANTHELMINTICS Antinematodals Anticestodals Antitrematodals ANTIPROTOZOALS ADULTICIDES and HEARTWORM PREVENTION

ANTINEMATODALS BENZIMIDAZOLES Attack beta tubulin which is a protein that is needed for cellular metabolism and cell division Usually have to apply more than one dose consecutively In addition to nematodes, some products can treat some flukes, cestodes, and protozoa Used in large animals, small animals, snakes, birds, rodents (note: not approved for cats, but is used) Oral pastes Side effects uncommon, but may include vomiting/diarrhea Have “azole” at the end of name Thiabendazole (EQUIZOLE, TBZ, OMNIZOLE) Fenbendazole (PANACUR/SAFEGUARD) Oxibendazole (ANTHELCIDE EQ) Albendazole (VALBAZEN) Oxfendazole (BENZELMIN) Mebendazole (TELMIN)

ANTINEMATODALS ORGANOPHOSPHATES and CARBAMATES Inactivate acetocholinesterase in parasites. This allows acetylcholine to overstimulate the nervous system and eventually cause paralysis (label usually says “contains a cholinesterase inhibitor”). Originally used as nerve gas. Not used as often with animals as they used to be. Break down quickly when exposed to light, air, and soil

ANTINEMATODALS ORGANOPHOSPHATES and CARBAMATES Used in large animals and small animals and also on plants Examples: Trichlorfon, Coumaphos (BAYMIX), Haloxon, Dichlorvos (TASK) To remember signs of toxicity, think SLUDDE (salivation, lacrimation, urination, defecation, dyspnea, emesis). Also bradycardia, miosis, muscle tremors, ataxia, paralysis Treat with ATROPINE or GLYCOPYRROLATE (block receptors for acetylcholine) and remove the insecticide. Glycopyrrolate reverses the neurological signs bc it crosses the blood brain barrier better than Atropine does.

ANTINEMATODALS TETRAHYDROPYRIMIDINES Cause paralysis of the parasite Large and small animals Most commonly used one is Pyrantel pamoate (NEMEX, STRONGID) Considered to be very safe Often found in feed stores Ineffective against tape worms IMIDATHIAZOLES Large and small animals and some exotics Examples include Febantel and Levamisole Can cause foaming at the mouth

ANTINEMATODALS Macrolides: Avermectins and Milbemycins Structurally similar with a macrocyclic ring that are derived for a Streptomyces bacterium. Stimulate glutamate receptors in nematodes, causing paralysis and death. Among the safest compounds to use in mammals (these receptors are located behind the blood-brain barrier within the CNS in mammals) AVERMECTINS Large and small animals, birds, and snakes Ivermectin, Selamectin, Doramectin, Eprinomectin

ANTINEMATODALS Ivermectin HEARTGARD, EQVALAN, IVOMEC Heartworm prevention, intestinal parasites, demodex, ear mites Oral or injectable Ivermectin toxicosis in collies Genetic (recessive) trait that causes a deficiency of P-glycoprotein, a protein that moves drugs from the blood brain barrier cells back into the blood Signs of toxicosis are CNS depression (ataxia, mydriasis) Heartgard doses are safe No antidote

ANTINEMATODALS Selamectin REVOLUTION Heartworm preventation, internal parasites, flea control, ear mites, sarcoptic mange (dogs), ticks (dogs) Topical

ANTINEMATODALS Doramectin DECTOMAX Internal worms, grubs, lice, mange Injectable and pour-on for cattle and swine Eprinomectin EPRINEX Internal worms, grubs, lice, mange Pour-on for cattle

ANTINEMATODALS MILBEMYCINS - Milbemycin oxime and Moxidectin Milbemycin oxime INTERCEPTOR, SENTINEL Heartworm preventative, hookworms, roundworms, ear mites, mange Oral tablet for dogs and cats Moxidectin QUEST, CYDECTIN Nematodes, mites, grubs, bots, lice, flies Cydectin is a pour on for cattle, Quest is an oral gel for horses

ANTINEMATODALS Piperazine Only effective against roundworms Partially or fully paralyzes the worm but does not kill it. Worms are sometimes passed a mass wiggling in the stool Tablets used in small animals, birds, and snakes Often found in once a month OTC dewormers Very safe PIPA-TABS

ANTICESTODALS Cause loss of intracellular calcium in the parasite, which leads to paralysis. Also, the tapeworm’s outer layer becomes permeable allowing antigens to leak out and the host to produce antibodies. Epsiprantel CESTEX Oral tablet for dogs and cats Does not treat Echinococcus Causes worm to disintegrate. Proglottids will not be seen in feces after administration. Not ovicidal.

ANTICESTODALS Praziquantel Injectable and tablets for dogs and cats DRONCIT Treats Dipylidium, Taenia, and Echinococcus Causes worm to disintegrate. Proglottids will not be seen in feces after administration. Not ovicidal. Remember that flea prevention must be administered when treating Dipylidium Combined with pyrantel pamoate in DRONTAL (add Febantel for DRONTAL PLUS)

ANTITREMATODALS Clorsulon is used in cattle for liver flukes CURATREM Albendazole is used in cattle for liver flukes VALBAZEN Praziquantel is used for lung flukes in small animals DRONCIT

ANTIPROTOZOALS Treat Coccidia, Giardia, and Sarcocystis neurona (EPM) Amprolium Calves and birds Causes thiamin deficiency in parasite Treats coccidia CORID Sulfadimethoxine An antimicrobial that also treats coccidia in small animals ALBON

ANTIPROTOZOALS Metronidazole Antibacterial and anti-inflammatory that treats Giardia High doses may cause neurological signs FLAGYL Fenbendazole Benzimidazole that treats Giardia PANACUR Ponazuril Treats Sarcocystis neurona and coccidia in horses MARQUIS

ADULTICIDE Melarsomine Dihydrochloride Kills adult Dirofilaria immitis Arsenic intramuscular lumbar injectable drug for dogs IMMITICIDE Injection site is commonly painful; many veterinarians provide pain-relieving medications Nodules may develop at injection sites Exercise restriction is imperative (dying worms live in pulmonary arteries) Worms will degenerate and cause inflammation in the lungs (steroids are often given for this) Adulticide is not administered to cats

HEARTWORM PREVENTION Selamectin REVOLUTION for dogs and cats Monthly topical medication. Also treats fleas (insecticidal), ear mites, sarcoptic mange (dogs), hookworms/roundworms (cats), and Dermacentor tick in dogs Milbemycin oxime INTERCEPTOR for cats and dogs Oral tablet given monthly Also treats hookworms, roundworms, and whipworms (dogs) Note: milbemycin is also an otic medication to treat Otodectes in cats

HEARTWORM PREVENTION o Milbemycin oxime + lufenuron SENTINEL for dogs Oral tablet given monthly Also treats hookworms, roundworms, whipworms, and fleas SENTINEL SPECTRUM = milbemycin oxime + lufenuron + praziquantel for added tapeworm protection Ivermectin HEARTGARD for cats and dogs Monthly oral medication (tablet or chewable) Cat med controls hookworms Dose is safe for collies Ivermectin + pyrantel pamoate= HEARTGARD PLUS (also controls hookworms and roundworms)

HEARTWORM PREVENTION Moxidectin PROHEART 6 Injectable 6 month preventative for dogs Also controls hookworms Milbemycin oxime + spinosad TRIFEXIS Monthly oral tablet for dogs Also controls fleas, hookworms, roundworms, and whipworms

DRUGS THAT TREAT ECTOPARASITES Fipronil FRONTLINE SPRAY and FRONTLINE TOP SPOT Topical solution for adult flea control Monthly application in dogs and cats Fipronil + methoprene = FRONTLINE PLUS (fleas and ticks). Methoprene is an IGR All are OTC Blocks GABA receptors, decreases chloride in neuron, hyperexcitability kills parasite.

DRUGS THAT TREAT ECTOPARASITES Imidacloprid ADVANTAGE Topical solution for flea control. Kills adults on contact. Monthly application in dogs and cats Blocks acetylcholine receptors Imidacloprid + pyriproxyfen = ADVANTAGE II (flea control for dogs and cats. Lice also for dogs). Pyriproxyfen is an IGR. Imidacloprid + pyriproxyfen + permethrin = K9 ADVANTIX II (fleas, ticks, lice and mosquito/fly repellant for dogs) NO CATS Imidacloprid + moxidectin = ADVANTAGE MULTI (fleas, roundworms, hookworms, ear mites, and heartworm preventative for cats….. Fleas, roundworms, hookworms, whipworms, sarcoptic mange, and heartworm preventative for dogs) Advantage Multi is Rx

DRUGS THAT TREAT ECTOPARASITES Nitenpyram CAPSTAR Oral tablet for flea control in dogs and cats Stimulates acetylcholine receptors causing increased nervous system activity (flea seizures, paralysis, and then death) Give as needed (can be daily). Kills adult fleas within 30 minutes of administration. Animal may begin to scratch. Give with an IGR or IDI for maximum flea control. OTC

DRUGS THAT TREAT ECTOPARASITES o Lufenuron PROGRAM Oral tablet for flea control in dogs and cats An IDI that interferes with chitin development (fleas exoskeleton). Does not kill adult fleas. Will have to wait two weeks before seeing improvement in flea infestation. Give with Capstar. Given once monthly. Cat’s dose is higher than dogs. 6 month Injectable and monthly oral solution available for cats (dogs have local reaction) Lufenuron + milbemycin= SENTINEL (flea control, heartworm preventative, hookworms, roundworm, and whipworms control in dogs) Distributed to all of the animal’s tissues once administered. Stored there and then redistributed into circulation over time. All are Rx Metaflumizone PROMERIS - Discontinued: linked to causing pemphigus

IGRs, IDIs, JMHs IGR: insect growth regulator. Affect immature stages of insects, preventing them from maturing. No adulticidal activity. IDI: insect development inhibitor (a type of IGR) also called a chitin synthesis inhibitor JMH: juvenile hormone mimics (a type of IGR) Products are distributed over an animal's skin and work by direct contact with the flea. Adult females absorb the drug and incorporate the IGR into the flea eggs. The eggs may hatch but the larvae won’t these products should be used with an adulticide. Lufenuron (Program) is an IDI that is ingested into flea when it feeds on an animal. Affects the flea’s ability to produce chitin which is located within the egg and the larvae’s exoskeleton. Therefore, Lufenuron won‘t kill adult fleas and it can take a couple weeks to see results. For this reason, Nitenpyram is usually given in the meantime. Pyriproxyfen (Nylar) is a JHM, which mimics juvenile hormone that is produced by the insect’s brain. When the insect’s body detects high levels of JH or a JHM, it fails to fully mature to the stage of egg production.

DRUGS THAT TREAT ECTOPARASITES Selamectin REVOLUTION Topical solution for flea control, heartworm prevention, ear mite treatment in dogs and cats (also treats hookworms and roundworms in cats) Monthly application Not technically an IGR, but does have some ovicidal effects Rx Spinosad COMFORTIS Oral tablet for flea prevention. Kills adults. Given monthly to dogs and cats Spinosad + milbemycin = TRIFEXIS (for dogs: controls fleas, hookworms, roundworms, whipworms, and is a heartworm preventative) Both are Rx

DRUGS THAT TREAT ECTOPARASITES Pyrethrins Extract of chrysanthemums used in many insecticides. Synthetic pyrethroids have a better killing effect than natural ones. Most pyrethroids end in “thrin” (ex: PERMETHRIN). Cause excessive amounts of sodium in the neuron, overstimulating it. Parasites will suffer seizures and paralysis. Highly toxic to cats, causes seizures and hypersalivation. Permethrin is used in a lot of products to repel ticks and people mistakenly apply it to cats. Rinse product off! Fish are also hypersensitive to toxicity, use with care around water.

DRUGS THAT TREAT ECTOPARASITES Formamidines Amitraz is the most commonly used Decreases release of norepinephrine, causing sedation. Don‘t use with other MAO inhibitors MITABAN for demodex treatment in dogs (also kills ticks) Wear gloves when applying dip! May cause transient sedation for up to 72 hours, hypothermia (drip dry), and pruritus Use caution with collars (PREVENTIC). If lost, monitor for signs of ingestion. TAKTIC for treatment of lice, mange, and ticks on large animals Can be reversed with yohimbine, tolazoline, and atipamezole

INSECT REPELLENTS Commonly used in human, large, and small animal products. Repel gnats, mosquitoes, and flies. When pyrethrins/pyrethroids are added, fleas and ticks are repelled. Sprays, tags, and topicals applied to ear tips Used on horses and cattle to prevent flies from laying eggs on the skin (leading to bots and warbles) Used on dogs with upright ears to prevent fly strike. Butoxypolypropylene glycol (BUTOX PPG) Diethyltoluamide (DEET) is often used in human products for insect repelling. Caused death in small animals.