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Effects of Ivabradine, A New Selective If Current Inhibitor, on Heart Rate in Cats

Cober, Richard E.

Abstract Details

2010, Master of Science, Ohio State University, Veterinary Clinical Sciences.
Heart rate is one of the main determinants of ischemia, a pathophysiologic characteristic of hypertrophic cardiomyopathy (HCM). Unwanted tachycardia may trigger decompensation in previously asymptomatic cats with HCM. Beta blockers are the primary medications used to reduce heart rate in cats, however, side effects or contraindications sometimes limit their use. Ivabradine is a highly selective If current inhibitor. The drug exerts negative chronotropic effects without significant effects on inotropy, lusitropy, or dromotropy in multiple species. Ivabradine, has never been studied in cats. The purpose of this study was to determine an effective oral dose of ivabradine to significantly reduce heart rate in healthy cats. In this single blinded, placebo controlled, randomized, fully-crossed study 8 healthy cats received placebo or one dose of ivabradine at 0.1 mg/kg, 0.3 mg/kg, or 0.5 mg/kg, PO. HR and blood pressure were monitored continuously for 24 hours via radiotelemetry after each treatment. Response to stress was studied twice by 15-min acoustic startle applied at baseline and 4 hours after drug. Statistical comparisons were made using a linear mixed model and 2-way repeated measures ANOVA. Peak negative chronotropic effect was observed 3 hours after ivabradine administration. Heart rate (min-1) decreased significantly (p<0.05) in a dose-dependent manner (mean±SD for placebo: 144±20; ivabradine 0.1 mg/kg: 133±22; ivabradine 0.3 mg/kg: 112±20; ivabradine 0.5 mg/kg, 104±11). Heart rate (min-1) was still reduced (p<0.05) at 12 hours after ivabradine (0.3 mg/kg: 128±18 and 0.5 mg/kg: 124±16) compared to placebo (141±21). Heart rate response to acoustic startle was significantly (p<0.01) blunted at all 3 doses of ivabradine. No effect of ivabradine on blood pressure was identified and no clinically discernable side effects were observed. These findings indicate that ivabradine at 0.3 mg/kg and 0.5 mg/kg PO predictably lowers HR for at least 12 hours in healthy cats. Clinical studies in cats with HCM are needed.
Karsten Schober, DVM, PhD (Advisor)
John Bonagura, DVM, MS (Committee Member)
Robert Hamlin, DVM, PhD (Committee Member)
60 p.

Recommended Citations

Citations

  • Cober, R. E. (2010). Effects of Ivabradine, A New Selective If Current Inhibitor, on Heart Rate in Cats [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1272998433

    APA Style (7th edition)

  • Cober, Richard. Effects of Ivabradine, A New Selective If Current Inhibitor, on Heart Rate in Cats. 2010. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1272998433.

    MLA Style (8th edition)

  • Cober, Richard. "Effects of Ivabradine, A New Selective If Current Inhibitor, on Heart Rate in Cats." Master's thesis, Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1272998433

    Chicago Manual of Style (17th edition)