June 19, 2003
Dear Doctor:
This letter is to provide another update of our field experiences with ProHeart
6 (moxidectin) as we pass the two year anniversary of its launch, and
some label additions being made to reflect some of these experiences, as noted
below. We trust that this information will be useful and encourage you to call
our Professional Services department if you have any additional questions after
reviewing this material.
There are two additions to the ProHeart 6 label that have either been made, or
are in the process of being made. The first was the label change regarding use
of ProHeart 6 in heartworm positive dogs. Briefly, the changes were made in
response to a low number of heartworm-positive dogs that experienced coughing
or cardiopulmonary signs after receiving ProHeart 6. The pre-approval clinical
studies did not identify any such reactions prior to release, and many
heartworm positive dogs have received ProHeart 6 without side effects. However,
based on reports received on a low number of heartworm positive dogs, Fort
Dodge, in conjunction with the Center for Veterinary Medicine, made the
following changes:
Under the heading "Post Approval Experience," the following statement was
added:
"Cardiopulmonary signs such as coughing and dyspnea may occur in
heartworm-positive dogs treated with ProHeart 6."
Additional labeling changes made under the "Precautions" section of the package
insert and printed cartons in conjunction with this statement included:
Removal of the statement "At the discretion of the veterinarian" before the
sentence "Infected dogs should be treated to remove adult heartworms."
The following statement was deleted "No adverse reactions were observed in dogs
with patent heartworm infections when ProHeart 6 was administered at three
times the labeled dose. Higher doses were not tested." (A similar
statement was already present in the Animal Safety section, and this statement
was left unchanged.)
The second label change is the recent decision to add a statement regarding the
rare occurrence of death in a low number of dogs treated with ProHeart 6.
Death has been reported in approximately 0.0025 percent of the doses sold into
veterinary clinics. Some of the reports are associated with severe allergic
events, while others appear to be multifactorial in nature. Some are
linked to factors not associated with product use.
We continue to investigate all reports as fully as possible. If and when
further information becomes available that has clinical implications on product
use, we will advise the veterinary community accordingly.
With regard to the label change, the following new statement, "and rare reports
of death" has been added to the "Post-Approval Experience" section under the
heading "ADVERSE REACTIONS". The full section "Post Approval Experience"
section now reads:
Post-Approval Experience: Although not all adverse events are reported, the
following reactions are based on voluntary post-approval drug experience
reporting: anaphylaxis/toid reactions, depression/lethargy, urticaria,
head/facial edema, and rare reports of death. Anaphylactic and anaphylactoid
reactions should be treated immediately with the same measures used to treat
hypersensitivity reactions to vaccines and other injectable products.
Cardiopulmonary signs such as coughing and dyspnea may occur in
heartworm-positive dogs treated with ProHeart 6.
This revised "Post-Approval Experience" statement will replace the current
wording, which appears in the ProHeart 6 package insert and on all approved
ProHeart 6 printed outer boxes.
In order to help educate your clients on both the benefits and potential side
effects associated with ProHeart 6 (moxidectin), Fort Dodge Animal Health has prepared a client
information sheet which contains questions and answers about use of the
product, and includes the product insert on the reverse side. An example copy
is attached for your reference. Additional quantities will be available to you
through your Fort Dodge representative and the sheet will soon be posted on our
websites for both veterinarians and clients to download and print.
Thank you for your attention to this important information. We feel it is
essential to provide you with timely updates on the use of this product.
Millions of doses of ProHeart 6 continue to be used safely, and we trust that
this reflects your on-going experience, as well. We continue our
monitoring activities and will provide any pertinent updates on ProHeart 6 as
they become available. Please feel free to contact one of our
Professional Services veterinarians at the number listed above if you have
additional questions or concerns regarding any of this information.
Sincerely,
Stephen A. Connell, DVM
Vice President,
Professional and Technical Services
