Drug Classification & Information

Pimobendan (Vetmedin) is an inodilator that increases contractility (strength) of the heart and dilates systemic arteries & veins.  This effect is achieved by inhibiting an enzyme called phosphodiesterase III (PDE III).  May have some phosphodiesterase V inhibition which may be helpful in the treatment of pulmonary hypertension.  Pimobendan is best given on an empty stomach as food decreases the availability of the medication.

Indications for Use

Pimobendan is labelled for the treatment of congestive heart failure (CHF) as a result of mitral valve disease and dilated cardiomyopathy (DCM) in dogs.  Recent studies have shown benefit to delay progression and extends survival of animals with mitral valve disease and DCM in the asymptomatic phase.  It may be used off-label for treatment of CHF related to other forms of heart disease.  May be helpful as an adjunctive therapy in the treatment of pulmonary hypertension. 

Potential Drug Interactions

Pimobendan is contraindicated in patients with valvular stenosis (aortic, pulmonic) as well as patients with hypertrophic obstructive cardiomyopathy.  In the asymptomatic stage of mitral valve disease it is indicated once moderate disease severity is reached (ACVIM Stage B3).  No significant drug interactions reported to date.

Drug Side Effects

The most common side effect noted is gastro-intestinal upset – anorexia, vomiting and diarrhea.  These signs may be self-limiting and may improve after initiation of therapy.  Pimobendan may increase risk for some arrhythmias but not well documented in large trials to date.

Therapeutic Monitoring

No specific monitoring for this medication; when used in conjunction with other treatments of CHF, thoracic radiographs are used to evaluate control of pulmonary edema.

Dosage Forms

Veterinary:  1.25, 2.5, 5 mg capsules (Vetmedin)