Milbemycin Oxime + Praziquantel

What is milbemycin oxime + praziquantel?

Milbemycin oxime + praziquantel (brand name Interceptor Plus®) is a heartworm disease preventive that also controls hookworms, roundworms, whipworms, and tapeworms in dogs.

How is milbemycin oxime + praziquantel given?

Milbemycin oxime + praziquantel is given by mouth as a flavored chew tablet. It must be given with food to ensure adequate absorption.

This medication should take effect within one to two days.

What if I miss giving my dog a scheduled dose?

Give the missed dose as soon as you remember, and then wait the amount of time between doses (as recommended by your veterinarian) before giving the next dose. Do not give your dog two doses at once or give extra doses.

If you are using milbemycin oxime + praziquantel as a heartworm preventive and more than eight weeks have passed without giving it to your dog, contact your veterinarian for guidance.

Are there any potential side effects?

At prescribed doses, milbemycin oxime + praziquantel is well-tolerated, but there are rare reports of vomiting, diarrhea, and transient appetite loss. Higher doses may cause more severe side effects. If any of the following signs are observed, contact your veterinarian immediately:

  • depression, lack of energy, or weakness
  • stumbling or collapse
  • seizures or coma 
  • dilated pupils 
  • excessive drooling

This medication should stop working in a few days, although the effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

Milbemycin oxime + praziquantel is safe for use in most pets. It should be used in dogs without a current negative heartworm test, puppies less than six weeks of age, or puppies or dogs weighing less than 2 lb (900 g).

Some dog breeds (e.g., collies, sheepdogs, and collie or sheepdog-cross breeds) are more sensitive to milbemycin than others. This is typically due to a specific genetic mutation (MDR1) that makes them less able to tolerate high doses of milbemycin. Appropriate doses are safe for these breeds (see the handout “Multidrug Resistance Mutation MDR1” for more information).

Use in pregnant or nursing animals has not been evaluated.

Your veterinarian will advise you on the safety of milbemycin oxime + praziquantel use in your dog.

Are there any drug interactions I should be aware of?

Certain drugs can interact with milbemycin, including cyclosporine (Atopica®), amiodarone, diltiazem, azole antifungals, and erythromycin. Interactions with praziquantel can occur with albendazole, cimetidine, dexamethasone, phenobarbital, and azole antifungals. Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

Your pet should be tested for heartworm before receiving any product containing milbemycin. A life-threatening reaction can occur if your pet has a high load of immature worms and is given milbemycin.

Screening may be done for dog breeds with a potential milbemycin sensitivity before receiving the drug. DNA testing can determine if a pet has the genetic mutation responsible for adverse reactions to milbemycin.

How do I store this medication?

Store milbemycin oxime + praziquantel products at room temperature, in a dry place away from heat and direct sunlight. Do not store this medicine in the bathroom, near the kitchen sink, or in damp areas. Exposure to heat or moisture may reduce the drug’s effectiveness.

What should I do in case of an emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are unavailable, follow their directions in contacting an emergency facility.

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