Doramectin

Products

Doramectin is commercially available as a pour-on solution (solution for pouring on) and as a solution for injection. It has been approved exclusively as a veterinary drug in many countries since 1995.

Structure and properties

Doramectin (C50H74O14, Mr = 899.1 g/mol) is a macrocyclic lactone and belongs to the avermectins. It is formed by fermentation of a strain of the soil-living actinomycete . Doramectin has strong structural similarity to ivermectin. At position 25, it has a lipophilic cyclohexyl group and thus a long half-life. It is very lipophilic and therefore hardly soluble in water.

Effects

Doramectin (ATCvet QP54AA03) is antiparasitic and antihelminthic with a broad spectrum of activity. It is effective against both internal and external parasites such as lice, mites, ticks, horn flies, worms, and caterpillars. Due to its long half-life of 4 to 8 days (depending on the species), Doramectin has a long-lasting effect of 4 to 9 weeks. Thus, Doramectin is effective not only therapeutically but also preventively. Resistance in sheep has been reported.

Mechanism of action

Doramectin increases membrane permeability to chloride ions in parasite neurons. This disrupts excitatory conduction, resulting in paralysis and death of the parasites.

Indications

Doramectin is used in cattle, sheep, and swine to treat and prevent infestations of worms, flies, mites, lice, and hair lice.

Dosage

According to the product label. Doramectin is administered as a single dose. The solution for injection is injected either subcutaneously or intramuscularly. The pour-on solution is distributed on the midline along the back of the animals. The skin must be clean and healthy for this purpose. All animals in a herd should always be treated with Doramectin at the same time.

Contraindications

Doramectin is contraindicated in cases of hypersensitivity. Toward the end of pregnancy in cows and sheep, Doramectin must not be administered. It must not be used in animals whose milk is intended for human consumption. In the case of the Pour-On solution, the user should avoid contact with the drug, as irritation of the skin and eyes may occur. For this reason, it is recommended to wear a waterproof coat, rubber gloves and rubber boots during handling. Doramectin is hazardous to fish and aquatic organisms. Therefore, it must not be released into water bodies and must be disposed of accordingly. Full precautions can be found in the drug label.

Interactions

Cattle that have received vaccination against lungworms should not be treated with doramectin for at least 2 weeks after the last vaccination.

Adverse effects

After injection has occurred, skin discoloration or mild inflammation may occur at the injection site. In the case of overdose, movement disorders and depression may occur in swine. In cattle, after application of the Pour-On solution, the animals may lick the drug back to themselves or each other. This results in reduced efficacy of the drug and the risk of resistance development.