Milbemycin Oxime: A Broad-Spectrum Antiparasitic Drug in Veterinary Medicine

General Description

Milbemycin oxime is a broad-spectrum antiparasitic drug used in veterinary medicine, particularly for dogs. It works by affecting the permeability of the parasite's cell membrane, leading to paralysis and death. Milbemycin oxime is commonly used to prevent heartworm disease and treat intestinal parasites such as roundworms, hookworms, and whipworms in dogs. The recommended dosage varies depending on the specific infection but is typically administered once a month for several months. Adverse reactions may occur, especially in dogs already infected with heartworms. It is important to consult with a veterinarian and conduct a blood test before administering milbemycin oxime.

Figure 1. Milbemycin oxime

Pharmacological Effects

Milbemycin oxime is a broad-spectrum antiparasitic drug that exhibits excellent killing effects on both internal and external parasites, particularly nematodes and arthropods. The drug binds to specific high-affinity sites on the target parasitic cells, affecting the permeability of the cell membrane to Cl-, thereby increasing the release of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in the nerve cells of nematodes and the muscle cells of arthropods. This leads to the opening of glutamate-gated Cl- channels and enhances the permeability of the nerve membrane to Cl-, thereby blocking the transmission of nerve signals, ultimately resulting in paralysis of the nervous system and loss of muscle contraction ability, leading to the death of the parasite. After oral administration in dogs, milbemycin oxime is slowly absorbed into the bloodstream. When given orally at a dose of 0.25 mg/kg body weight, the maximum plasma concentration of milbemycin oxime reaches 74.1 ng/ml after approximately 4 hours. The absorption half-life is 1.1 hours, and the elimination half-life is 11.7 hours. Within 48 hours, over 90% of the drug is distributed to tissues and body fluids, followed by a slow decline as it is cleared from the body. ¹

Pet Pharmaceutical Applications

Milbemycin oxime is widely used as an antiparasitic drug in veterinary medicine, particularly for dogs. It has several pet pharmaceutical applications and is effective in preventing heartworm infection and eliminating certain intestinal parasites. One of the main indications for milbemycin oxime is the prevention of canine heartworm disease. Heartworm is a serious and potentially fatal condition that is transmitted through mosquito bites. Milbemycin oxime works by killing the larvae of the heartworms, preventing them from developing into adult worms and causing harm to the dog's cardiovascular system. In addition to its heartworm preventive properties, milbemycin oxime is also effective against various intestinal parasites in dogs. It can eliminate roundworms, hookworms, and whipworms, which are common parasites that can cause gastrointestinal issues and other health problems in dogs. Overall, milbemycin oxime is a valuable medication in veterinary practice, providing protection against heartworm disease and helping to control and treat intestinal parasite infections in dogs. It is important to consult with a veterinarian for proper dosing and administration of milbemycin oxime based on the specific needs and conditions of individual pets. ²

Dosage and Caution

Milbemycin oxime is a medication used for the prevention and treatment of certain parasitic infections in dogs. It is primarily used to prevent heartworm disease, which is caused by the parasite Dirofilaria immitis. The recommended dosage for heartworm prevention is 0.25-0.5mg per kilogram of body weight, administered once a month. It is advised to start administering the medication one month before the mosquito season begins and continue until one month after the season ends. Milbemycin oxime can also be used to treat roundworm and hookworm infections in dogs. The dosage for these infections is the same as for heartworm prevention, given once a month for at least two consecutive months. For whipworm infections, the recommended dosage is 0.5-1mg per kilogram of body weight, administered once a month for at least two consecutive months. Some potential adverse reactions of Milbemycin oxime include lethargy, decreased appetite, and vomiting in dogs already infected with heartworms. Before administering this medication, it is important to have a blood test to check for heartworm infection. Dogs that are already infected should be treated for adult heartworms and microfilariae before starting Milbemycin oxime. ²

Reference

1. Dos Santos KC, Tielemans E, Cutolo AA, et al. Efficacy of an oral formulation of afoxolaner and milbemycin oxime against Tunga penetrans in naturally infected dogs. Parasit Vectors. 2023;16(1):446.

2. Rania Gollakner, BS, DVM, MPH. Milbemycin Oxime. VCA Animal Hospitals.