Hemodynamic effects of benazepril, an angiotensin-converting enzyme inhibitor, as studied in conscious normotensive dogs

Safety of a benazepril and pimobendan combination tablet in adult healthy dogs

The objective of the study was to investigate the safety of a combination tablet of benazepril and pimobendan, Fortekor PLUS^® , in a randomized, blinded, parallel-group design study in healthy adult beagle dogs. The test article, Fortekor PLUS^® tablets, was administered orally twice daily for 6 months at one, two, and four times the highest recommended dosage of 0.5 mg/kg benazepril hydrochloride/0.25 mg/kg pimobendan (four males and four females per group). An additional control group was sham-dosed. Fortekor PLUS^® did not induce any treatment-related effects on body weight, food consumption, neurological, ophthalmologic or physical assessments over the 6-month treatment period. The test article was possibly associated with an increased frequency of occasional vomiting. Fortekor PLUS^® was associated with small, but significant, increases in heart rate and reductions in PR and QT intervals, which were assessed by electrocardiography. These effects were most probably related to reflex tachycardia secondary to reduced systemic blood pressure. Statistically significant changes in some clinical pathology variables were noted after test article administration, but were considered to be of no clinical relevance as values remained within reference ranges and/or were not dose-dependent. No treatment-related macroscopic or microscopic findings were observed. In conclusion, Fortekor PLUS^® tablets were well tolerated in healthy adult dogs when administered at one, two, and four times the highest recommended dosage for 6 months.

Efficacy of monotherapy with benazepril, an angiotensin converting enzyme inhibitor, in dogs with naturally acquired chronic mitral insufficiency

Benazepril (BP), an angiotensin convertive enzyme inhibitor, was administered orally once daily for 4 weeks to 31 dogs with mild to moderate (NYHA functional classes II and III) congestive heart failure caused from mitral insufficiency (MI). There were no significant changes in clinical signs, electrocardiogram findings, radiographical observations and plasma biochemical results in 11 dogs treated with placebo for 4 weeks. In 31 dogs treated with BP, appetite increased, and mean scores of heart failure signs, such as activity, exercise tolerance, cough and respiratory effort, were significantly improved. No dog displays signs suggesting systemic hypotension. One dog died suddenly on the 26th day of treatment with BP. This dog had good vigor and appetite till the evening before the death, and cough and exercise tolerance had been gradually improving. The heart rate and ECG parameters of BP treated dogs did not change significantly, but length of long axis of the heart decreased. In plasma biochemical tests, plasma urea nitrogen (UN) levels did not change significantly, and plasma creatinine (CRE) levels increased slightly within the normal ranges during BP trial. Two dogs had higher plasma UN levels with slightly higher plasma CRE levels, but had normal general condition and other biochemical results. Plasma ACE activity decreased to 57.3% of pre-treatment level at 4 weeks after BP treatment. It is concluded that BP monotherapy was efficacious at least in dogs with relatively low grade congestive heart failure caused by MI.