1. Why is ProHeart® 6 coming back on the U.S. market?
Since the product’s recall in 2004, the manufacturers of ProHeart® 6 (Fort Dodge Animal Health) have conducted studies to further evaluate the safety profile of ProHeart® 6 and to provide an explanation for the reported adverse events. These studies included additional toxicologic and pharmacologic evaluations which suggested the allergenic nature of some of the residual solvents that are utilized in the manufacture of ProHeart® 6. As a result, Fort Dodge has changed the manufacturing specifications for ProHeart® 6 and has marketed the product in international markets. In the years following this change, there has been a decline in the adverse event reporting in international markets. The results of the toxicologic studies coupled with the low adverse event frequency in international markets were factors in FDA’s decision to concur with Fort Dodge’s restricted return of ProHeart® 6 to the U.S. market under a risk minimization plan.
2. What changes have been made to the labeling since it was last marketed in the U.S.?
Based on post-approval experience, the ProHeart® 6 label and Client Information Sheet have been revised to include updated safety information [link to label and CIS] The new label includes warnings to not administer ProHeart® 6 within 1 month of vaccinations, and use the product with caution in dogs with pre-existing allergic disease, including food allergy, atopy [skin allergies], and flea allergy dermatitis. The label also advises not to administer the drug to dogs who are sick, debilitated, underweight, or who have a history of weight loss. In addition, the Post-Approval Experience section of the label has been updated and includes reported adverse reactions, such as liver and blood disorders.
3. Does the risk minimization and restricted distribution program make it harder for veterinarians to purchase ProHeart® 6?
The intent of the program is to make veterinarians and their clients aware of the possible risks associated with ProHeart® 6 in determining appropriate use of the drug. Therefore, the program will limit the purchase of ProHeart® 6 by veterinarians directly from Fort Dodge Animal Health, to ensure veterinarians receive the in-depth training prior to obtaining the drug. Once veterinarians have become registered in the program, they can purchase ProHeart® 6 as needed.
4. What must a veterinarian do to register with Fort Dodge Animal Health before purchasing ProHeart® 6?
Prior to purchasing ProHeart® 6, veterinarians will have to complete in-depth training [link to Web-based slides]; confirm they have read the new label and the conditions of use; provide the owner with the client information sheet and obtain signed informed consent; and report any adverse events.
5. Has CVM/FDA taken this approach with any other veterinary drugs?
This is the first veterinary drug that will be marketed under a strengthened risk minimization and restricted distribution program. However, numerous drugs for use in people have been successfully marketed under similar risk minimization programs since 2002.
6. Considering the available heartworm preventives, how to I determine if ProHeart® 6 is appropriate for my dog?
The tools provided in the program allow veterinarians to weigh the risk of heartworm disease in their patients with the benefits of using the drug, thus maximizing heartworm protection, while minimizing the risk to dogs. Veterinarians and dog owners will be able to discuss the individual needs of the patient, including the relative risk of heartworm disease (heartworm endemic areas, ability of dog owner to give monthly medications, etc.), in making the best decision for the dog.
7. What should a dog owner do if they suspect their dog is experiencing an adverse event to ProHeart® 6?
Dog owners should immediately contact their veterinarian to initiate appropriate veterinary care. Their veterinarian will contact Fort Dodge to report any adverse events (800) 533-8536.
8. Aren’t there enough alternatives on the market already? (Or is there a recognized shortage of anti-heartworm drugs for dogs?)
Veterinarians prefer to have as many pharmacologic choices as possible in their arsenal of products from which to choose when preventing heartworm in dogs. ProHeart 6 is the only FDA approved injectable heartworm preventive that is labeled for 6 months of protection, thus greatly minimizing owner compliance issues. In some of the heartworm prevalent areas of the United States, missing one monthly medication on a prevention program timetable could mean the difference between a dog becoming heartworm positive or not. The veterinarian plays a critical role in determining along with their dog owner clients, the appropriate heartworm program for each of their canine patients.
9. How frequent is it for the FDA to allow a drug (even in limited form) back on the market after it has been removed from the market?
FDA did not withdraw ProHeart 6 from the market. The company voluntarily suspended marketing until they could address the safety concerns raised by FDA scientists.
It will be difficult to provide the exact number of drugs that sponsors have stopped marketing for a period of time. FDA works with all sponsors to ensure that their drugs are safe and to address any safety concerns as quickly as possible when such concerns are raised.
Two human drugs that were removed from the market and then came back under a restricted distribution plan are: Accutane and Lotronex.
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