Pimobendan Dosing for Dogs with Heart Failure
Pimobendan (Vetmedin) should be administered twice daily (every 12 hours) at a dose of 0.5 mg/kg/day divided into two equal portions for dogs with heart failure. 1
Dosing Details
- Standard dose: 0.5 mg/kg/day divided into two approximately equal portions
- Administration frequency: Every 12 hours (twice daily)
- Formulation: Oral tablets (Vetmedin)
Evidence Supporting Twice Daily Dosing
The FDA-approved drug label for pimobendan clearly establishes the dosing frequency as twice daily. In the pivotal clinical trials that led to its approval, pimobendan was administered "0.5 mg/kg/day divided into 2 portions that were not necessarily equal, and the portions were administered approximately 12 hours apart" 1. This twice-daily dosing regimen demonstrated significant clinical efficacy in dogs with congestive heart failure due to myxomatous mitral valve disease (MMVD) or dilated cardiomyopathy (DCM).
Clinical Efficacy
Pimobendan's effectiveness with twice-daily dosing has been demonstrated in multiple clinical trials:
In the QUEST study, pimobendan administered at 0.4-0.6 mg/kg/day in divided doses significantly extended survival time compared to benazepril in dogs with congestive heart failure due to MMVD (median 267 days vs 140 days) 2
The EPIC study showed that pimobendan given at 0.4-0.6 mg/kg/day in divided doses to dogs with preclinical MMVD and cardiomegaly delayed the onset of congestive heart failure by approximately 15 months compared to placebo 3
Pharmacokinetic Considerations
The twice-daily dosing schedule aligns with pimobendan's pharmacokinetic profile. When administered orally, pimobendan reaches maximum plasma concentration (Cmax) at approximately 2.1 hours post-administration, with a half-life of about 1.8 hours 4. The active metabolite, O-desmethyl-pimobendan, has a longer half-life of approximately 5 hours 4. This pharmacokinetic profile supports the need for twice-daily administration to maintain therapeutic drug levels throughout the day.
Clinical Benefits of Twice-Daily Dosing
Twice-daily administration of pimobendan provides several important clinical benefits:
- Sustained hemodynamic effects: Maintains positive inotropic effects throughout the 24-hour period
- Reduced mitral regurgitation: Studies show pimobendan decreases mitral regurgitation severity 5
- Improved cardiac function: Reduces heart size, which is associated with improved outcomes 6
Practical Administration Tips
- Administer approximately 12 hours apart to maintain consistent drug levels
- Can be given with or without food
- If a dose is missed, administer as soon as possible, but do not double the next dose
Monitoring
When initiating pimobendan therapy, monitor:
- Clinical signs of heart failure
- Exercise tolerance
- Respiratory rate and effort
- Heart size via radiography or echocardiography at follow-up visits
Conclusion
The established dosing regimen for pimobendan in dogs with heart failure is twice daily (every 12 hours) at a total daily dose of 0.5 mg/kg divided into two approximately equal portions. This dosing schedule is supported by the FDA-approved label and multiple clinical trials demonstrating improved survival and quality of life in dogs with heart failure.