Afoxolaner

Afoxolaner_structure.svg

Afoxolaner is an antiparasitic drug used in veterinary medicine. It is a member of the isoxazoline class of compounds and is primarily used to treat and prevent flea and tick infestations in dogs. Afoxolaner is marketed under the brand name NexGard.

Mechanism of Action

Afoxolaner works by inhibiting the function of gamma-aminobutyric acid (GABA) receptors and glutamate-gated chloride channels in the nervous system of arthropods. This leads to uncontrolled neuronal activity, resulting in the death of the parasites. The drug is highly selective for the GABA receptors in insects and arachnids, making it safe for use in mammals.

Pharmacokinetics

After oral administration, afoxolaner is rapidly absorbed into the bloodstream. It has a high bioavailability and reaches peak plasma concentrations within a few hours. The drug is metabolized in the liver and excreted primarily through the urine and feces.

Indications

Afoxolaner is indicated for the treatment and prevention of:

• Flea infestations (Ctenocephalides felis)
• Tick infestations, including species such as Rhipicephalus sanguineus, Dermacentor variabilis, Amblyomma americanum, and Ixodes scapularis

Dosage and Administration

Afoxolaner is administered orally, typically in the form of a chewable tablet. The dosage is based on the dog's weight, and it is usually given once a month. It is important to follow the veterinarian's instructions and the manufacturer's guidelines for proper dosing.

Safety and Side Effects

Afoxolaner is generally well-tolerated in dogs. However, some common side effects may include:

• Vomiting
• Diarrhea
• Lethargy
• Anorexia

In rare cases, more severe reactions such as seizures may occur, particularly in dogs with a history of neurological disorders. It is important to consult a veterinarian if any adverse effects are observed.

Contraindications

Afoxolaner should not be used in dogs with known hypersensitivity to the drug or any of its components. It is also not recommended for use in puppies less than 8 weeks of age or weighing less than 4 pounds.

Interactions

There are no known significant drug interactions with afoxolaner. However, it is always advisable to inform the veterinarian of any other medications or supplements the dog is currently taking.

Regulatory Status

Afoxolaner is approved by the United States Food and Drug Administration (FDA) for use in dogs. It is available by prescription from a licensed veterinarian.

See Also

• Isoxazoline
• NexGard
• Flea treatment
• Tick treatment