Veterinary Drug Series - ivermectin

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1. Introduction

Ivermectin, CAS number: 70288-86-7, is a derivative of avermectin,

Ivermectin is a new broad-spectrum, high-efficiency and low-toxicity anti-parasitic drug, which has a good repellent effect on in vivo and in vivo parasites, especially nematodes and arthropods. However, it is not effective against tapeworms, flukes, and protozoa.

The repellent effect of macrolide antiparasitic drugs on nematodes and arthropods is to increase the release of the inhibitory transmitter γ-aminobutyric acid [GABA] of the worm body, as well as open the glutamate-controlled Cl ion channel, enhance the permeability of the nerve membrane to Cl, thereby blocking the transmission of nerve signals, and eventually nerve paralysis, so that muscle cells lose their ability to contract, resulting in the death of the worm.

2. Pharmacological effects

For example, when sheep take a preparation containing Tween-80 as an adjuvant, ivermectin dosage of 4000μg/kg is still very safe, but if propylene glycol is used as an adjuvant, it will cause ataxia and hemoglobinuria in sheep for 3 days.

Ivermectin injection with Tween-80 adjuvant in the United States is a commercial preparation for equine animals, but it cannot be used in dogs, otherwise it is extremely unsafe.


3. Use

Ivermectin is widely used in gastrointestinal nematodes, lung nematodes and parasitic arthropods in cattle, sheep, horses and pigs, intestinal nematodes in dogs, ear mites, scabies mites, heartworms and microfilariae, as well as poultry gastrointestinal nematodes and ectoparasites.

(l) Cattle and sheep: ivermectin is given to cattle and sheep by oral or subcutaneous injection at a dose of 0.2mg/kg, and the deworming rate is 97%~100% for blood spear nematode, Oster nematode, Cooper nematode, Trichostrongyloides (including Trichostrongylus elliec), round nematode, eupation nematode, fine-necked nematode, hairy nematode, esophageal mouth nematode, nettail nematode and sheep Charbert's nematode adult and stage 4 larvae.

(2) Horses: 0.2mg/kg for three kinds of equine stomach maggots that migrate or have a gastric residence period, onchocercia microfilariae that cause skin damage, and the third stage larvae of gastric nematodes, although a single application is 0. The 2 mg/kg dose is also limited, but the best regimen is to repeat the dose after one month. Of particular significance, the recommended dose of ivermectin (0.2mg/kg) has an effective rate of about 99% in the treatment of mesenteric artery damage caused by the migratory phase of the early and 4th larvae of common round nematodes, usually after 2 days of medication, the symptoms are significantly reduced, and all the damage symptoms disappear in about 28 days.

(3) Pigs: intramuscular injection of 0.3mg/kg ivermectin has broad-spectrum anthelmintic activity on pigs. The above-mentioned medication also has a good control effect on pig blood lice and scabies mites.

(4) Dogs and cats: there are special dosage forms [according to 6~12 μg/kg) in foreign countries for the prevention and treatment of canine heartworm microfilariae infection, and China can try 50μg/kg oral administration method to treat heartworm microfilariae infection (adult worm is ineffective).


(5) Poultry: It is highly effective for poultry nematodes such as chicken roundworms and occlusive capillary nematodes and poultry parasitic arthropods, such as knee mites (mutant knee mites), etc., according to the amount of 200~300μg/kg or subcutaneous injection. However, this product is ineffective against chicken isospiny nematode.

(6) Reindeer: For reindeer bovine skin fly maggot (Oedemagena tarandi) infection, subcutaneous injection can be done according to the dosage of cattle (200μg/kg).


4. Adverse reactions

Overdose can cause poisoning, and there is no specific antidote. Intramuscular injections can produce severe local reactions.

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