FDA Conditionally Approves First Drug to Delay Onset of Congestive Heart Failure in Dogs

June 16, 2022

Today the U.S. Food and Drug Administration conditionally approved Vetmedin-CA1 (pimobendan) chewable tablets, the first drug indicated for delaying the onset of congestive heart failure in dogs with Stage B2 preclinical myxomatous mitral valve disease (MMVD). MMVD is a condition in dogs where an abnormal heart valve allows blood to leak backward (regurgitation), impacting the ability of the heart to pump blood and resulting in an enlarged heart (cardiomegaly). If left untreated, this condition may lead to heart failure and fluid accumulation in the lungs. Stage B2 preclinical MMVD refers to dogs with MMVD that have not yet developed signs of heart failure but have a moderate or loud mitral murmur due to a leaking mitral heart valve and have an enlarged heart.

MMVD occurs in many breeds of dogs. It most frequently occurs in smaller breed dogs, including Cavalier King Charles Spaniels, Yorkshire terriers, and dachshunds. MMVD should be diagnosed by a veterinarian based on comprehensive physical and cardiac examinations.

While Vetmedin is already fully approved for the management of the signs of mild, moderate, or severe congestive heart failure in dogs due to MMVD or dilated cardiomyopathy, the conditionally approved indication for Vetmedin-CA1 is the first for dogs in the preclinical stage of MMVD who have a heart murmur and an abnormal enlargement of the heart but are not yet in congestive heart failure. In those dogs, Vetmedin-CA1 delays the onset of congestive heart failure, slowing the progression of MMVD. Vetmedin and Vetmedin-CA1 contain the same active ingredient, pimobendan, at the same dose, but will be marketed separately with two separate labels and unique application numbers.

An animal drug that addresses a serious or life-threatening disease, or addresses an unmet animal or human health need, for which demonstrating effectiveness would require complex or particularly difficult study or studies is eligible for conditional approval. The FDA determined that Vetmedin-CA1 is eligible for conditional approval because it met all of these criteria.

Conditional approval allows an animal drug sponsor to legally market its product after demonstrating that the drug is safe and manufactured in accordance with full approval standards, and that there is a reasonable expectation of the drug’s effectiveness. The initial conditional approval is valid for one year with the potential for up to four annual renewals. During this time, the animal drug sponsor must demonstrate active progress toward proving substantial evidence of effectiveness for full approval. The animal drug sponsor has five years to obtain full approval after receiving conditional approval, or it will no longer be allowed to be marketed.

The reasonable expectation of effectiveness of Vetmedin-CA1 was established in a long-term, multi-center field study in client-owned dogs that had cardiomegaly and met certain criteria for MMVD. Enrolled dogs were started on either Vetmedin-CA1 or a control chewable tablet with no active ingredient. The study monitored the length of time from when the dogs started treatment until when they either developed left-sided congestive heart failure or died or were euthanized due to cardiac disease (primary endpoints). The median time from starting treatment to reaching one of these primary endpoints was 1,228 days in the Vetmedin-CA1 group compared to 761 days in the control group, a difference of 467 days (15.6 months).

Adverse reactions were seen in dogs in both the Vetmedin-CA1 and control groups. Many of these reactions are associated with the natural progression of MMVD and the age of enrolled dogs. Cough was the most frequently reported adverse reaction, which is commonly reported in dogs with MMVD, and the incidence was similar between the Vetmedin-CA1 and control groups. Lethargy, lack of appetite, rapid breathing (tachypnea), collapse, irregular heartbeat (arrhythmia), and temporary loss of consciousness caused by decreased blood pressure (syncope) were reported in dogs treated with Vetmedin-CA1 and may also be associated with the progression of MMVD. Adverse reactions unrelated to the progression of MMVD in dogs treated with Vetmedin-CA1 included diarrhea, vomiting, pain, lameness, arthritis, urinary tract infection, and seizure.

Vetmedin-CA1 is only available by prescription from a licensed veterinarian because veterinary expertise is required to diagnose MMVD, and to determine if Vetmedin-CA1 is an appropriate treatment. Dogs suspected of having MMVD should undergo a comprehensive physical and cardiac examination. Vetmedin-CA1 should only be used in dogs with preclinical MMVD that have a moderate or loud heart murmur due to mitral regurgitation and cardiomegaly (Stage B2 MMVD, 2019 ACVIM Consensus Statement).

The FDA granted conditional approval of Vetmedin-CA1 to Boehringer Ingelheim Animal Health USA.

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Issued by FDA Center for Veterinary Medicine.
For questions, Contact CVM.