Hemodynamic effect of pimobendan following intramuscular and intravenous administration in healthy dogs: A pilot study

Abstract

BackgroundPimobendan is widely used for the treatment of dogs with heart failure via the oral route. A new injectable form of pimobendan is now available and its potential usefulness via intravenous route has been recently demonstrated in dogs. However, the cardiovascular effects of intramuscular (IM) administration of injectable pimobendan have not been investigated yet.HypothesisIM administration of pimobendan may have the same hemodynamic effect as the IV route.MethodsSix healthy Beagle dogs underwent a placebo-controlled double-blind crossover study. The early cardiovascular effects after a single dose of IM and IV injections of pimobendan (0.2 ml/kg; Pimo IM and Pimo IV, respectively) were compared to the same volume of IM placebo (Saline IM) in anesthetized dogs. Clinical [heart rate (HR) and blood pressure (BP)] and echocardiographic hemodynamic parameters [left ventricular (LV) inflow waveforms of diastolic early wave (eV), atrial systolic wave (aV), diastolic early mitral ring velocity (e′), peak velocity (pV), stroke volume (SV), cardiac output (CO), and systemic vascular resistance (SVR)] were monitored with 15 min intervals for 120 min.ResultsDiastolic BP decreased significantly at 30 min in Pimo IM compared to Saline IM. Mean eV and CO values significantly increased from 75 min, e′ from 60 min, pV from 75 min, and SV from 15 to 120 min, whereas SVR significantly decreased at 30–60 min in Pimo IM compared to those of Saline IM (P < 0.05). Compared with the Pimo IV, eV and pV were significantly lower at 30–60 min (P < 0.05) while SV was significantly higher at 90–105 min in Pimo IM (P < 0.05). Other hemodynamic parameters (BP, HR, SVR, CO, e′, and E/e′) did not significantly change between Pimo IM and IV.ConclusionsThe hemodynamic effect of pimobendan following IM and IV injection was described. Our results suggested that IM administration of pimobendan is equally comparable and possibly interchangeable with IV administration. This warrant further studies to investigate the clinical effectiveness of IM pimobendan in treating dogs with congestive heart failure or in heart failure cases unable to receive IV or oral administration.

Changes in echocardiographic indices and left ventricular strain values by two-dimensional speckle-tracking echocardiography following pre-anesthetic oral pimobendan administration compared with intravenous pimobendan in dogs

“…Compared to the Control group, ESVI and LVIDSN remained lower without significant change from baseline, and EF and FS remained higher without significant change from baseline in the PIMO PO and PIMO IV groups over anesthesia time. These findings suggest that pimobendan primarily affects LV systolic function and contractility, which is consistent with the main effects of pimobendan identified in previous studies ( 6 , 11 , 13 , 15 , 16 , 33 , 35 , 43 , 44 ). A significant maintenance of LV contractility was observed with both oral and intravenous pimobendan.…”

“…The third anesthesia (PIMO IV group) was administered to compare the effects of oral and intravenous pimobendan administration in 8 dogs, which consisted of 5 from the previous anesthesia groups and 3 new dogs that had never undergone the study-related anesthesia. The measurement intervals and methods were modified and adapted from previous studies ( 13 , 27 ). Accordingly manufacturer’s instructions, 0.15 mg/kg IV pimobendan (Vetmedin 5 mL solution for injection, Boehringer Ingelheim, Barcelona, Spain) was injected 10 min after propofol induction in the third anesthesia.…”

“…Recent studies have shown that single-dose intravenous pimobendan administration improves cardiac function by increasing systolic output and left ventricle (LV) contractility in dogs under inhalational anesthesia ( 11 , 12 ). Another study compared the efficacy and hemodynamic effects of intravenous and intramuscular pimobendan in anesthetized dogs ( 13 ). Although the short- and long-term echocardiographic changes induced by oral pimobendan have been studied in unanesthetized dogs ( 14 – 16 ), no study has evaluated the effects of single-dose oral pimobendan premedication during general anesthesia in dogs.…”

Haemodynamic Effects of Pimobendan during General Anaesthesia in Healthy Senior Dogs: A Prospective, Randomised, Triple-Blinded, Placebo-Controlled Clinical Study

“…It has also been shown to increase CO and reduce systemic vascular resistance in dogs with mitral valve degeneration [ 12 ]. Nonetheless, its effects during the administration of anaesthesia in dogs without heart disease have only been studied in experimental young and adult dogs using invasive methods [ 15 , 16 , 17 , 18 , 19 ] or echocardiography [ 29 ]. Until now, no clinical studies have assessed the effects of pimobendan in healthy senior dogs under general anaesthesia.…”

“…It is also commonly used to determine stroke volume via echocardiography by multiplying VTI by the cross-sectional area of the aorta [ 35 ]. This echocardiographic assessment has been used in several studies to assess the effects of pimobendan in dogs [ 18 , 29 , 36 ]. Minute distance (MD: VTI multiplied by HR) is directly related to CO and has often been used as an alternative method to assess CO [ 32 ].…”