Prevalence was similar in the active control group. The
mg/kg orally. The effect was still present 8 hours
only 4 and 7% of the tablets offered, the average
prevalence of renal failure was higher in the active con-
after dosing. There was a delay between peak blood
trol group (4%) compared to the Vetmedin group (1%).
levels of pimobendan and active metabolite and the
maximum physiologic response (peak LV dP/dtmax).
Animal Safety: In a laboratory study, Vetmedin chew-
Adverse reactions/new clinical findings were seen in
Blood levels of pimobendan and active metabolite
able tablets were administered to 6 healthy Beagles
both treatment groups and were potentially related to
Vetmedin®
began to drop before maximum contractility was seen.
per treatment group at 0 (control), 1, 3, and 5 times
CHF, the therapy of CHF, or both. The following adverse
Repeated oral administration of pimobendan did not
the recommended dosage for 6 months. See Table 3
reactions/new clinical findings are listed according to
result in evidence of tachyphylaxis (decreased positive
for cardiac pathology results. The cardiac pathology/
body system and are not in order of prevalence: CHF
inotropic effect) or drug accumulation (increased
histopathology noted in the 3X and 5X dose groups is
death, sudden death, chordae tendineae rupture, left
typical of positive inotropic and vasodilator drug toxicity
positive inotropic effect). Laboratory studies indicate
atrial tear, arrhythmias overall, tachycardia, syncope,
that the positive inotropic effect of pimobendan may
in normal dog hearts, and is associated with exagger-
weak pulses, irregular pulses, increased pulmonary
Caution: Federal law restricts this drug to use by or on
be attenuated by the concurrent use of a ß-adrenergic
ated hemodynamic responses to these drugs. None of
edema, dyspnea, increased respiratory rate, coughing,
the order of a licensed veterinarian.
blocker or a calcium channel blocker.
the dogs developed signs of heart failure and there was
gagging, pleural effusion, ascites, hepatic congestion,
Description: Vetmedin (pimobendan) is supplied as
decreased appetite, vomiting, diarrhea, melena, weight
Effectiveness: In a double-masked, multi-site, 56-day
oblong half-scored chewable tablets containing 1.25,
loss, lethargy, depression, weakness, collapse, shaking,
field study, 355 dogs with modified NYHA Class II, III,
Table 3: Incidence of Cardiac Pathology/
2.5 or 5 mg pimobendan per tablet. Pimobendan,
trembling, ataxia, seizures, restlessness, agitation,
or IV CHF due to AVVI or DCM were randomly assigned
Histopathology in the Six-month Safety Study
a benzimidazole-pyridazinone derivative, is a non-
pruritus, increased water consumption, increased
to either the active control (enalapril maleate) or the
sympathomimetic, non-glycoside inotropic drug
urination, urinary accidents, azotemia, dehydration,
Vetmedin (pimobendan) treatment group. Of the 355
Severe left ventricular hypertrophy One 3X and
with vasodilatative properties. Pimobendan exerts a
abnormal serum electrolyte, protein, and glucose
dogs, 52% were male and 48% were female; 72%
with multifocal two 5X dogsa
stimulatory myocardial effect by a dual mechanism
values, mild increases in serum hepatic enzyme levels,
were diagnosed with AVVI and 28% were diagnosed
subendocardial ischemic lesions
of action consisting of an increase in calcium
and mildly decreased platelet counts.
with DCM; 34% had Class II, 47% had Class III, and
sensitivity of cardiac myofilaments and inhibition of
19% had Class IV CHF. Dogs ranged in age and weight
Moderate to marked myxomatous Three 5X dogs
See Table 1 for mortality due to CHF (including
phosphodiesterase (Type III). Pimobendan exhibits
from 1 to 17 years and 3.3 to 191 lb, respectively. The
thickening of the mitral valves
euthanasia, natural death, and sudden death) and for
vasodilating activity by inhibiting phosphodiesterase
most common breeds were mixed breed, Doberman
the development of new arrhythmias (not present in a
III activity. The chemical name of pimobendan is 4,5-
Pinscher, Cocker Spaniel, Miniature/Toy Poodle, Maltese,
Myxomatous thickening of the One 3X and
dog prior to beginning study treatments) by treatment
chordae tendineae two 5X dogs
dihydro-6-[2-(4-methoxyphenyl)-1H-benzimidazole-5-
Chihuahua, Miniature Schnauzer, Dachshund, and
group and type of heart disease (AVVI or DCM) in the
yl]-5-methyl-3(2H)-pyridazinone. The structural formula
Cavalier King Charles Spaniel. The 180 dogs (130 AVVI,
Endocardial thickening of the left One 1X, two 3X,
50 DCM) in the active control group received enalapril
ventricular outflow tract and two 5X dogs Table 1: CHF Death and New Arrhythmias in the 56-Day
maleate (0.5 mg/kg once or twice daily), and all but 2
Field Study
received furosemide. Per protocol, all dogs with DCM in
Left atrial endocardial thickening One 3X and
the active control group received digoxin. The 175 dogs
(jet lesions) in 2 of the dogs that one 5X dog
(126 AVVI, 49 DCM) in the Vetmedin group received
developed murmurs of mitral valve insufficiency Vetmedin® Group Active Control Group
pimobendan (0.5 mg/kg/day divided into 2 portions
that were not necessarily equal, and the portions were
Granulomatous inflammatory lesion One 3X dog
administered approximately 12 hours apart), and all but
in the right atrial myocardium Indications: Vetmedin (pimobendan) is indicated for
4 received furosemide. Digoxin was optional for treating
the management of the signs of mild, moderate, or
supraventricular tachyarrhythmia in either treatment
Most of the gross and histopathologic findings oc-
Dogs that
severe (modified NYHA Class IIa , IIIb , or IVc ) congestive
group, as was the addition of a ß-adrenergic blocker if
heart failure in dogs due to atrioventricular valvular
digoxin was ineffective in controlling heart rate. After
Murmurs of mitral valve insufficiency were detected in
insufficiency (AVVI) or dilated cardiomyopathy (DCM).
initial treatment at the clinic on Day 1, dog owners were
one 3X (Day 65) and two 5X dogs (Days 135 and 163).
Vetmedin is indicated for use with concurrent therapy
to administer the assigned product and concurrent
These murmurs (grades II-III of VI) were not associated
for congestive heart failure (e.g., furosemide, etc.) as
appropriate on a case-by-case basis.
The determination of effectiveness (treatment success)
Indirect blood pressure was unaffected by Vetmedin at
a A dog with modified New York Heart Association
for each case was based on improvement in at least
Dogs that
the label dose (1X). Mean diastolic blood pressure was
(NYHA) Class II heart failure has fatigue, shortness of
2 of the 3 following primary variables: modified
developed
decreased in the 3X group (74 mmHg) compared to the
breath, coughing, etc. apparent when ordinary exercise
NYHA classification, pulmonary edema score by a
control group (82 mmHg). Mean systolic blood pressure
arrhythmiasa
masked veterinary radiologist, and the investigator’s
overall clinical effectiveness score (based on physical
was decreased in the 5X group (117 mmHg) compared
b A dog with modified NYHA Class III heart failure is
to the control group (124 mmHg). None of the dogs had
examination, radiography, electrocardiography, and
comfortable at rest, but exercise capacity is minimal.
clinical pathology). Attitude, pleural effusion, coughing,
activity level, furosemide dosage change, cardiac
New arrhythmias included supraventricular premature
A dog with modified NYHA Class IV heart failure has
On 24-hour Holter monitoring, mean heart rate was
beats and tachycardia, atrial fibrillation, atrioventricular
size, body weight, survival, and owner observations
no capacity for exercise and disabling clinical signs are
increased in the 5X group (101 beats/min) compared to
block, sinus bradycardia, ventricular premature beats
were secondary evaluations contributing information
the control group (94 beats/min). Not counting escape
supportive to product effectiveness and safety. Based
beats, the 3X and 5X groups had slightly higher num-
Dosage and Administration: Vetmedin should be
on protocol compliance and individual case integrity,
bers of isolated ventricular ectopic complexes (VEs). The
administered orally at a total daily dose of 0.23 mg/lb
Following the 56-day masked field study, 137 dogs
265 cases (134 Vetmedin, 131 active control) were
maximum number of non-escape VEs recorded either at
(0.5 mg/kg) body weight, using a suitable combination
in the Vetmedin group were allowed to continue
evaluated for treatment success on Day 29. See Table 2
baseline or in a control group dog was 4 VEs/24 hours.
of whole or half tablets. The total daily dose should be
on Vetmedin in an open-label extended-use study
At either Week 4 or Week 20, three 3X group dogs had
divided into 2 portions that are not necessarily equal,
without restrictions on concurrent therapy. The adverse
Table 2: Effectiveness Results for the
maximums of 33, 13, and 10 VEs/24 hours, and two 5X
and the portions should be administered approximately
reactions/new clinical findings in the extended-use
56-Day Field Study
group dogs had maximums of 22 and 9 VEs/24 hours.
12 hours apart (i.e., morning and evening). The tablets
study were consistent with those reported in the 56-day
One 1X group dog with no VEs at baseline had 6 VEs/24
are scored and the calculated dosage should be
study, with the following exception: One dog in the
hours at Week 4 and again at Week 20. Second-degree
provided to the nearest half tablet increment.
extended-use study developed acute cholestatic liver
Vetmedin® Group Active Control Group
atrioventricular heart block was recorded in one 3X
failure after 140 days on Vetmedin and furosemide.
group dog at Weeks 4 and 20, and in one dog from each
Contraindications: Vetmedin should not be given in
of the 1X and 5X groups at Week 20. None of the dogs
cases of hypertrophic cardiomyopathy, aortic stenosis,
In foreign post-approval drug experience reporting,
had clinical signs associated with these electrocardio-
or any other clinical condition where an augmentation
the following additional suspected adverse reactions
Treatment
of cardiac output is inappropriate for functional or
were reported in dogs treated with a capsule formula-
Success on
tion of pimobendan: hemorrhage, petechia, anemia,
Treatment was associated with small differences in
hyperactivity, excited behavior, erythema, rash, drooling,
mean platelet counts (decreased in the 3X and 1X
Warnings: Only for use in dogs with clinical evidence
constipation, and diabetes mellitus.
groups), potassium (increased in the 5X group), glucose
of heart failure. At 3 and 5 times the recommended
(decreased in the 1X and 3X groups), and maximum
dosage, administered over a 6-month period of time,
To report suspected adverse reactions, to obtain a
blood glucose in glucose curves (increased in the 5X
pimobendan caused an exaggerated hemodynamic
Material Safety Data Sheet, or for technical assistance
group). All individual values for these variables were
response in the normal dog heart, which was associated
within the normal range. Three 1X and one 5X group
with cardiac pathology (See Animal Safety). Treatment Clinical Pharmacology: Pimobendan is oxidatively
dogs had mild elevations of alkaline phosphatase (less
Success on
than two times normal). Loose stools and vomiting were
Human Warnings: Not for use in humans. Keep this
demethylated to a pharmacologically active metabolite
and all medications out of reach of children. Consult a
which is then conjugated with sulfate or glucuronic
physician in case of accidental ingestion by humans.
acid and excreted mainly via feces. The mean extent
Storage Information: Store at controlled room tempera-
of protein binding of pimobendan and the active
Precautions: The safety of Vetmedin has not been
metabolite in dog plasma is >90%. Following a single
No increase in
established in dogs with asymptomatic heart disease or
oral administration of 0.25 mg/kg Vetmedin tablets
furosemide How Supplied:
in heart failure caused by etiologies other than AVVI or
the maximal mean (± 1 SD) plasma concentrations
dose between
Vetmedin® (pimobendan) Chewable Tablets:
DCM. The safe use of Vetmedin has not been evaluated
(Cmax) of pimobendan and the active metabolite were
Available at 1.25, 2.5 or 5 mg oblong half-scored chew-
in dogs younger than 6 months of age, dogs with
3.09 (0.76) ng/mL and 3.66 (1.21) ng/mL, respectively.
congenital heart defects, dogs with diabetes mellitus or
Individual dog Cmax values for pimobendan and the
At the end of the 56-day study, dogs in the Vetmedin
other serious metabolic diseases, dogs used for breed-
active metabolite were observed 1 to 4 hours post-dose
group were enrolled in an unmasked field study to
ing, or pregnant or lactating bitches.
(mean: 2 and 3 hours, respectively). The total body
monitor safety under extended use, without restrictions
clearance of pimobendan was approximately 90
Adverse Reactions: Clinical findings/adverse reactions
mL/min/kg, and the terminal elimination half-lives
were recorded in a 56-day field study of dogs with
of pimobendan and the active metabolite were
Vetmedin was used safely in dogs concurrently
congestive heart failure (CHF) due to AVVI (256 dogs)
approximately 0.5 hours and 2 hours, respectively.
receiving furosemide, digoxin, enalapril, atenolol,
or DCM (99 dogs). Dogs were treated with either
Boehringer Ingelheim Vetmedica, Inc.
Plasma levels of pimobendan and active metabolite
spironolactone, nitroglycerin, hydralazine, diltiazem,
Vetmedin (175 dogs) or the active control enalapril
were below quantifiable levels by 4 and 8 hours after
antiparasitic products (including heartworm
maleate (180 dogs). Dogs in both treatment groups
oral administration, respectively. The steady-state
prevention), antibiotics (metronidazole, cephalexin,
received additional background cardiac therapy (See
volume of distribution of pimobendan is 2.6 L/kg
amoxicillin-clavulanate, fluoroquinolones), topical
Effectiveness for details and the difference in digoxin
Vetmedin® is a registered trademark of Boehringer
indicating that the drug is readily distributed into
ophthalmic and otic products, famotidine, theophylline,
administration between treatment groups).
Ingelheim Vetmedica GmbH licensed to Boehringer
tissues. Food decreased the bioavailability of an
levothyroxine sodium, diphenhydramine, hydrocodone,
aqueous solution of pimobendan, but the effect of
The Vetmedin group had the following prevalence (per-
metoclopramide, and butorphanol, and in dogs on
food on the absorption of pimobendan from Vetmedin
cent of dogs with at least one occurrence) of common
Copyright 2007 Boehringer Ingelheim Vetmedica, Inc.
adverse reactions/new clinical findings (not present in a
or an affiliated company. All Rights Reserved. Palatability: In a laboratory study, the palatability of
dog prior to beginning study treatments): poor appetite
In normal dogs instrumented with left ventricular
Vetmedin was evaluated in 20 adult female Beagle dogs
(38%), lethargy (33%), diarrhea (30%), dyspnea (29%),
(LV) pressure transducers, pimobendan increased
offered doses twice daily for 14 days. Ninety percent (18
azotemia (14%), weakness and ataxia (13%), pleural
LV dP/dtmax (a measure of contractility of the heart)
of 20 dogs) voluntarily consumed more than 70% of the
effusion (10%), syncope (9%), cough (7%), sudden
in a dose dependent manner between 0.1 and 0.5
28 tablets offered. Including two dogs that consumed
death (6%), ascites (6%), and heart murmur (3%).
The 500-mg Invirase tablets are beige and im-printed with “ROCHE” on one side and “SQV 500” on the other side. Also known as: Ro 31-8959, saquinavir mesylate, SQV Patient assistance. Roche offers a patient assistance program for Background and description. This drug is a protease inhibitor those who qualify. For more information call 800.282.7780. man u fac tured by F. H