イベルメクチン

Ivermectin

22,23-dihydroavermectin B1a + 22,23-dihydroavermectin B1b

抗寄生虫薬 - マクロライド系（アベルメクチン）POSCIMTopical犬猫小型哺乳類フェレット鳥爬虫類馬牛豚羊ヤギ

別名: Heartgard · Ivomec · Equimectrin · Eqvalan · Zimectrin · Equimax · Phoenectin · Tri-Heart Plus · Panacur Plus · Stromectol · Otimectin Vet · Panomec · MK 933 · Ivermectine · Ivermectinum · Ivermectina

VetSheet 獣医チームが監修更新日 2026年4月5日エビデンスに基づく獣医学リファレンス

6-12 micrograms/kg PO once monthlyPO· once monthly

体重— 🐕

用量は獣医専門家向けの臨床参考資料です。必ず最新の医薬品情報および個別症例に基づいて確認してください。

動物種別用量

🌎 NA — North America🌍 EU — Europe

犬

適応	用量	経路	頻度	期間	地域
As a preventative for heartworm	6-12 micrograms/kg PO once monthly	PO	once monthly	—	🌎 NA
As a preventative for heartworm	Minimum dosage of 6 micrograms/kg (0.006 mg/kg) PO per month.	PO	per month	—	🌎 NA
As a microfilaricide	6-12 micro-grams/kg PO once a month	PO	once a month	—	🌎 NA
As an adulticide or pre-adulticide for heartworm (with doxycycline)	6-14 micrograms/kg PO once every 15 days for 6 months	PO	once every 15 days	6 months	🌎 NA
For generalized demodicosis	Day 1: 100 micrograms/kg PO q24h, Day 4: 200 micrograms/kg PO q24h, Day 7: 300 micrograms/kg; continue to increase by 100 micro-grams/kg every 3rd day until reach target dose of 600 micrograms/kg PO daily	PO	q24h	1-2 months after 2 negative skin scrapes	🌎 NA
For demodicosis (alternative protocol)	Start at a trial dose of 0.05 mg/kg (50 micrograms/kg) day 1. Then increase the dose to 0.12 mg/kg for the next week... go up to 0.2 mg/kg for the next 3 days, and then increase the dose weekly by 0.1 mg/kg until you reach 0.6 mg/kg.	PO	daily	2 months past negative scrapings	🌎 NA
As scabicide	300-400 micrograms/kg PO or SC once weekly for weeks.	PO/SC	once weekly	for weeks	🌎 NA
For treatment of parasitic lung disease (Capillaria spp.)	0.2 mg/kg PO once	PO	once	—	🌎 NA
For Oslerus osleri	0.4 mg/kg SC once	SC	once	—	🌎 NA
For Eucoleus boehmi	0.2 mg/kg PO once	PO	once	—	🌎 NA
For Pneumonyssoides caninum	0.2 mg/kg SC once	SC	once	—	🌎 NA

As a microfilaricide: To kill third, fourth, and young fifth stage larvae. Alternatively, 50 micrograms/kg for rapid kill (higher risk of adverse effects).
As an adulticide or pre-adulticide for heartworm (with doxycycline): Used in combination with doxycycline 10 mg/kg PO once daily for 30 days.
For generalized demodicosis: Do not use in ABCB1-1Δ susceptible breeds unless tested normal/normal.
As scabicide: Beware in sensitive breeds.

猫

適応	用量	経路	頻度	期間	地域
As a preventative for heartworm	0.024 mg/kg (24 micrograms/kg) PO every 30-45 days	PO	every 30-45 days	—	🌎 NA
For Aelurostrongylus abstrusus	0.4 mg/kg SC once	SC	once	—	🌎 NA
Ear mites	1 mg/g ear gel	topical	Not specified	Not specified	🌍 EU

As a preventative for heartworm: Also controls hookworms at this dosage.
Ear mites: Otimectin Vet. Do not use in kittens under 16 weeks.

小型哺乳類

適応	用量	経路	頻度	期間	地域
Rabbits: For Sarcoptes scabiei, Notoedres cati	0.3-0.4 mg/kg SC, repeat in 14 days.	SC	repeat in 14 days	—	🌎 NA
Rabbits: For ear mites (Psoroptes)	0.2-0.44 mg/kg PO, SC repeat in 8-18 days	PO/SC	repeat in 8-18 days	—	🌎 NA
Rabbits: For treatment of ear mites	200 micrograms/kg SC and repeated in two weeks.	SC	repeated in two weeks	—	🌎 NA
Rodents and lagomorphs: For treatment of sarcoptoid and some fur mites	200-250 micrograms/kg SC.	SC	once	—	🌎 NA
Mice, Rats, Gerbils, Guinea pigs, Chinchillas	200 micrograms/kg SC or PO every 7 days for 3 weeks	SC/PO	every 7 days	3 weeks	🌎 NA
Hamsters	200-500 micrograms/kg SC or PO every 14 days for 3 weeks	SC/PO	every 14 days	3 weeks	🌎 NA
Guinea pigs for Trixacarus caviae mites	500 micrograms/kg SC, repeated at 14 and 28 days.	SC	repeated at 14 and 28 days	—	🌎 NA

Rabbits: For treatment of ear mites: All rabbits in colony should be treated.

フェレット

適応	用量	経路	頻度	期間	地域
For prevention of heartworm disease	0.02 mg/kg PO monthly	PO	monthly	—	🌎 NA
To treat heartworm disease using the very slow protocol	50 micrograms PO once a month.	PO	once a month	—	🌎 NA

鳥

適応	用量	経路	頻度	期間	地域
For ascarids, Capillaria, Knemidocoptes pilae	Inject 220 micrograms/kg IM; Amazons: 0.1 mg IM; Macaws: 0.2 mg IM; Finches: 0.02 mg	IM	once	—	🌎 NA
For most species	200 micrograms/kg IM or orally; repeat in 10-14 days.	IM/PO	repeat in 10-14 days	—	🌎 NA
Budgerigars	0.01 mL of diluted product (see above) IM or PO	IM/PO	once	—	🌎 NA
For most species	200 micrograms/kg (0.2 mg/kg) SC; dilute using propylene glycol.	SC	once	—	🌎 NA
Ratites	200 micrograms/kg PO, IM or SC.	PO/IM/SC	once	—	🌎 NA

For ascarids, Capillaria, Knemidocoptes pilae: Dilute to a 2 mg/mL concentration or dilute bovine prep 1:4 with propylene glycol.
Ratites: Has efficacy against Chandlerella quiscali in emus.

爬虫類

適応	用量	経路	頻度	期間	地域
For most nematodes, ectoparasites (Lizards, snakes, alligators)	0.2 mg/kg (200 micrograms/kg) IM, SC, or PO once; repeat in 2 weeks.	IM/SC/PO	repeat in 2 weeks	—	🌎 NA

For most nematodes, ectoparasites (Lizards, snakes, alligators): A third treatment can be given if still positive. Toxic to chelonians, indigo snakes, skinks.

馬

適応	用量	経路	頻度	期間	地域
For susceptible parasites	200 micrograms/kg (0.2 mg/kg) PO using oral paste or oral liquid	PO	once	—	🌎 NA
For lice and mange	0.2 mg/kg PO; 0.2 mg/kg PO at 4 day intervals	PO	at 4 day intervals	—	🌎 NA
As a larvicidal for arterial stages of S. vulgaris	0.2 mg/kg once	PO	once	—	🌎 NA

牛

適応	用量	経路	頻度	期間	地域
For susceptible parasites	200 micrograms/kg SC.	SC	once	—	🌎 NA
For psoroptic mange	200 mg/kg IM	IM	once	—	🌎 NA
For susceptible parasites	200 micrograms/kg (0.2 mg/kg) SC under the loose skin in front of or behind the shoulder	SC	once	—	🌎 NA

For susceptible parasites: Doses greater than 10 mL should be given at two separate sites.
For psoroptic mange: Note: Reference was written before approval of the SC labeled bovine product; isolate from other cattle for at least 5 days after treatment.

豚

適応	用量	経路	頻度	期間	地域
For susceptible parasites	300 micrograms/kg (0.3 mg/kg) SC in the neck immediately behind the ear	SC	once	—	🌎 NA
For general control of endo- and ectoparasites in potbellied pigs	300 micro-grams/kg SC or IM once for internal parasites and repeated in 10-14 days for external parasites	SC/IM	once, repeat in 10-14 days	—	🌎 NA

For general control of endo- and ectoparasites in potbellied pigs: Only partially effective against whipworms.

羊

適応	用量	経路	頻度	期間	地域
For nasal bot infection	200 micrograms/kg	SC/PO	once	—	🌎 NA
For susceptible parasites	200 micrograms/kg SC for one dose	SC	once	—	🌎 NA
For adjunctive treatment of meningeal worm (Parelaphostrongylus tenuis)	0.3 mg/kg SC once daily for 5 days	SC	once daily	5 days	🌎 NA
Camelids: For susceptible parasites	0.2 mg/kg PO or SC for one dose	PO/SC	once	—	🌎 NA
Camelids: For GI helminths	0.2 mg/kg PO once.	PO	once	—	🌎 NA
Camelids: For adjunctive treatment of meningeal worm	0.3 mg/kg SC once daily for 5 days.	SC	once daily	5 days	🌎 NA

For adjunctive treatment of meningeal worm (Parelaphostrongylus tenuis): Given with fenbendazole (50 mg/kg PO once daily for 5 days).
Camelids: For adjunctive treatment of meningeal worm: Given with fenbendazole. Camelids very susceptible to GI ulcers; give prophylaxis.

ヤギ

適応	用量	経路	頻度	期間	地域
For susceptible parasites	200 micrograms/kg SC for one dose	SC	once	—	🌎 NA

用量は獣医専門家向けの臨床参考資料です。必ず最新の医薬品情報および個別症例に基づいて確認してください。

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概要

イベルメクチンは、多くの獣医種で広く使用されている代表的なアベルメクチン系抗寄生虫薬です。広範囲の線虫および節足動物に対して高い有効性を示すマクロライド系誘導体です。

主な臨床的特徴:

FDA承認用途: 犬および猫の犬糸状虫（フィラリア）予防。牛、豚、馬、トナカイ、バイソンの胃腸内線虫、肺虫、ウシバエ幼虫、シラミ、ダニの治療。
適応外使用: ミクロフィラリア駆除、緩徐な成虫駆除（通常ドキシサイクリンと併用）、小動物の全身性毛包虫症および疥癬の治療。
遺伝的感受性: ABCB1-1Δ（旧MDR1）変異を持つ犬種（コリー、オーストラリアン・シェパード、シェルティ、ロングヘアード・ウィペットなど）には細心の注意が必要です。これらの犬は血液脳関門のP-糖タンパク質ポンプが機能しておらず、疥癬やミクロフィラリア治療の一般的な用量で重篤かつ致命的な中枢神経毒性を引き起こす可能性があります。
毒性プロファイル: 低用量のフィラリア予防薬としては一般に安全ですが（MDR1変異犬でも）、高用量またはP-糖タンパク質阻害薬との併用により神経毒性のリスクが著しく増加します。

作用機序

Ivermectin exerts its antiparasitic effect by binding selectively and with high affinity to glutamate-gated chloride channels which occur in invertebrate nerve and muscle cells.

Primary Mechanism: Binds to glutamate-gated chloride channels → increases cell membrane permeability to chloride ions → hyperpolarization of the nerve or muscle cell → flaccid paralysis and death of the parasite.
Secondary Mechanism: Enhances the release of gamma-aminobutyric acid (GABA) at presynaptic neurons. GABA acts as an inhibitory neurotransmitter → blocks post-synaptic stimulation → paralysis.

Pharmacology Pearl: Because flukes (trematodes) and tapeworms (cestodes) do not utilize GABA as a peripheral nerve transmitter and lack glutamate-gated chloride channels, ivermectin is completely ineffective against these parasites. Mammals generally lack glutamate-gated chloride channels, and mammalian GABA receptors are confined to the CNS, which ivermectin does not readily cross (unless the P-glycoprotein pump is defective or overwhelmed), providing a wide margin of safety.

安全性・警告

禁忌

Foals less than 4 months old (manufacturer recommendation)
Puppies less than 6 weeks old
Breeds susceptible to ABCB1-1Δ (MDR1) mutation at high doses (unless tested normal)
Chelonians (turtles, tortoises)
Indigo snakes
Skinks
Lactating dairy animals (no milk withdrawal established)
Females of breeding age (cattle/swine, per label)
Dogs with the MDR1 (ABCB1) gene mutation (unless using strictly at low heartworm preventative doses)
Chelonians (turtles and tortoises) - causes fatal flaccid paralysis
Kittens under 16 weeks of age (for topical ear gel)
Use of concentrated livestock formulations in small animals

有害事象

Horses: Ventral midline swelling and pruritus (hypersensitivity to dying Onchocerca microfilariae)
Dogs: Shock-like reaction (when used as microfilaricide), depression, hypothermia, vomiting
Dogs (MDR1/Toxicity): Ataxia, lethargy, hypersalivation, mydriasis, tremors, seizures, blindness, coma
Cats: Agitation, vocalization, anorexia, mydriasis, rear limb paresis, tremors, disorientation, blindness
Cattle: Paralysis/staggering or salivation/bloat (if Hypoderma bovis larvae are killed in vital areas), injection site swelling
Birds: Lethargy, anorexia, death (especially in finches and budgerigars)
Neurotoxicity (ataxia, tremors, mydriasis, blindness, coma, death) - especially in MDR1-mutant dogs
Bradycardia

注意事項

MDR1 Gene Mutation Warning: Ivermectin is actively transported out of the CNS by the P-glycoprotein pump. Dogs with the ABCB1-1Δ (formerly MDR1) mutation have a defective pump, allowing ivermectin to accumulate in the brain, causing severe neurotoxicity. Always test susceptible breeds (Collies, Shelties, Australian Shepherds, Long-haired Whippets, 'white feet' breeds) before using extra-label high doses. Heartworm preventative doses are generally safe.

Species Sensitivities: Highly toxic to chelonians (turtles/tortoises), indigo snakes, and skinks. Finches and budgerigars are highly sensitive.
Cattle Grubs: Treating cattle for Hypoderma bovis when larvae are migrating through the spinal canal or esophagus can cause severe host reactions (paralysis or bloat) due to larval death in vital areas.
Food Animal Withdrawal: Strict adherence to slaughter withdrawal times is required. Not approved for lactating dairy animals.
Administration: Injectable products for cattle and swine are for SC use only; do not administer IM or IV.

医薬品相互作用

Benzodiazepines

Effects may be potentiated by ivermectin; concurrent use is not advised.

Ketamine

Avoid ivermectin in reptiles within 10 days of ketamine administration.

SpinosadMajor

Increased risk of neurotoxicity; do not use with high extra-label doses of ivermectin.

Amiodarone