Pimobendan 74150-27-9

Pimobendan (CAS 74150-27-9) is an inodilator — a positive inotrope and vasodilator — used exclusively in veterinary cardiology for the management of congestive heart failure (CHF) in dogs. As the active ingredient in Vetmedin, pimobendan works through dual mechanisms: calcium sensitization of cardiac myofilaments and selective inhibition of phosphodiesterase III (PDE-III). This combination increases cardiac contractility without raising myocardial oxygen demand while simultaneously reducing both preload and afterload.

Veterinary Cardiology Applications

Myxomatous Mitral Valve Disease (MMVD): The EPIC trial (Evaluation of Pimobendan In dogs with Cardiomegaly) demonstrated that pimobendan delays the onset of CHF by a median of 15 months in dogs with preclinical MMVD (Stage B2). This landmark study changed the standard of care, establishing pimobendan as the first drug proven to extend the preclinical period in canine heart disease.

Dilated Cardiomyopathy (DCM): In large and giant breed dogs prone to DCM (Doberman Pinschers, Great Danes, Irish Wolfhounds), pimobendan improves survival time and quality of life when used in combination with standard CHF therapy (furosemide, ACE inhibitors). The PROTECT study showed pimobendan significantly prolongs the time to onset of clinical signs in preclinical Doberman DCM.

Species-Specific Dosing

Dogs: 0.25-0.3 mg/kg orally twice daily (total daily dose 0.5-0.6 mg/kg), administered approximately 1 hour before feeding for optimal absorption. The dose is consistent across all stages of CHF (ACVIM Stage B2 through Stage D). Pimobendan should not be used in dogs with hypertrophic cardiomyopathy, subaortic stenosis, or any condition where augmentation of cardiac output is inappropriate.

Cats: Off-label use has been investigated at 0.625-1.25 mg per cat twice daily for feline CHF secondary to cardiomyopathy, though evidence remains limited compared to canine data.

Regulatory & Pharmacopeia References

Pimobendan is licensed for veterinary use in dogs in the EU (EMA), USA (FDA-CVM, NADA 141-273), and numerous other markets. It is classified as a veterinary-only medicine with no approved human indication. Quality specifications for pimobendan API are available in the European Pharmacopoeia (Ph. Eur.) and USP veterinary monographs.