Long-term therapy with benazepril in patients with congestive heart failure: effects on clinical status and exercise tolerance

The effect of benazepril on survival times and clinical signs of dogs with congestive heart failure: Results of a multicenter, prospective, randomized, double-blinded, placebo-controlled, long-term clinical trial

OBJECTIVE

To test the efficacy and tolerability of long-term administration of the angiotensin converting enzyme inhibitor, benazepril, in dogs with heart failure.

METHODS

The study was a prospective, randomized, double-blind, placebo-controlled clinical trial involving 16 centers in France, Italy, Switzerland and UK. A total of 162 dogs with class II and III (ISACHC classification) heart failure caused by chronic valvular disease (CVD) or dilated cardiomyopathy (DCM) were enrolled. Benazepril (minimum dosage, 0.25 mg/kg) or placebo were administered orally once daily for up to 34 months, either alone or as add-on therapy to "standard therapy" i.e. diuretics and/or digoxin and/or anti-arrhythmic drugs.

RESULTS

The mean survival time (to death or withdrawal from the study due to worsening of heart failure) was 2.7 times longer in the benazepril treated group (428 days) as compared with the placebo group (158 days). Differences reached statistical significance (p<0.05 Cox proportional hazards model, 44% reduction in risk). The survival rate after one year was 49% with benazepril and 20% with placebo. Benazepril produced a statistically significant (p<0.05) reduction (by 46%) in the risk of worsening of heart failure (to ISACHC class III) when therapy was initiated early (in ISACHC class II). In sub-group analyses, a statistically significant (p<0.05) benefit of benazepril was reached for both survival and worsening endpoints for dogs with CVD (n=125), but not for the small sample of dogs with DCM (37). Benazepril also improved the exercise tolerance and global clinical condition at day 28 (p<0.05). As compared to the placebo group, dogs treated with benazepril presented with the same frequency of undesirable clinical events and fewer biochemical disturbances (less frequent increases in plasma urea or creatinine and decreases in plasma potassium).

CONCLUSIONS

Benazepril extended the useful life-span of dogs with ISACHC class II and III heart failure (due to CVD) and was well tolerated.

Antihypertensive and organ-protective effects of benazepril

Benazepril is a nonsulfhydryl ACE inhibitor with favorable pharmacodynamic and pharmacokinetic properties, well-established antihypertensive effects and a good tolerability profile. Recent clinical studies have demonstrated that patients treated with benazepril alone or in combination with hydrochlorothiazide or amlodipine may achieve beneficial renal outcomes that extend beyond blood pressure control. Furthermore, the recent Avoiding Cardiovascular Events Through Combination Therapy in Patients Living with Systolic Hypertension (ACCOMPLISH) trial showed decreased cardiovascular morbidity and mortality with benazepril when administered as a cotreatment. An additional novel therapeutic area for benazepril is atrial fibrillation. Differences between combination therapies have implications for which patients may be best suited to particular interventions, and further studies are required to fully ascertain this potential.

Association of circulating angiotensin converting enzyme activity with respiratory muscle function in infants

Background

Angiotensin converting enzyme (ACE) gene contains a polymorphism, consisting of either the presence (I) or absence (D) of a 287 base pair fragment. Deletion (D) is associated with increased circulating ACE (cACE) activity. It has been suggested that the D-allele of ACE genotype is associated with power-oriented performance and that cACE activity is correlated with muscle strength. Respiratory muscle function may be similarly influenced. Respiratory muscle strength in infants can be assessed specifically by measurement of the maximum inspiratory pressure during crying (Pi_max). Pressure-time index of the respiratory muscles (PTImus) is a non-invasive method, which assesses the load to capacity ratio of the respiratory muscles.

The objective of this study was to determine whether increased cACE activity in infants could be related to greater respiratory muscle strength and to investigate the potential association of cACE with PTImus measurements as well as the association of ACE genotypes with cACE activity and respiratory muscle strength in this population.

Methods

Serum ACE activity was assayed by using a UV-kinetic method. ACE genotyping was performed by polymerase chain reaction amplification, using DNA from peripheral blood. PTImus was calculated as (Pi_mean/Pi_max) × (Ti/Ttot), where Pi_mean was the mean inspiratory pressure estimated from airway pressure, generated 100 milliseconds after an occlusion (P_0.1), Pi_max was the maximum inspiratory pressure and Ti/Ttot was the ratio of the inspiratory time to the total respiratory cycle time. Pi_max was the largest pressure generated during brief airway occlusions performed at the end of a spontaneous crying effort.

Results

A hundred and ten infants were studied. Infants with D/D genotype had significantly higher serum ACE activity than infants with I/I or I/D genotypes. cACE activity was significantly related to Pi_max and inversely related to PTImus. No association between ACE genotypes and Pdi_max measurements was found.

Conclusions

These results suggest that a relation in cACE activity and respiratory muscle function may exist in infants. In addition, an association between ACE genotypes and cACE activity, but not respiratory muscle strength, was demonstrated.

Adverse effects of ACE inhibitors in patients with chronic heart failure and/or ventricular dysfunction : meta-analysis of randomised clinical trials

BACKGROUND

The evidence-based benefit/risk evaluation of therapeutic interventions in randomised clinical trials should include both the assessment of the benefits and of the adverse outcomes. There is ample evidence that ACE inhibitors improve the symptoms and prognosis of chronic heart failure (CHF) and ventricular dysfunction. However, there is little systematic information on the tolerability and adverse effects associated with their use in these conditions.

OBJECTIVE

To estimate the adverse events related to ACE inhibitor use in the treatment of CHF and ventricular dysfunction.

DESIGN AND METHODS

Description of adverse events in reports of randomised clinical trials of ACE inhibitors in CHF or ventricular dysfunction was examined, and a meta-analysis was performed. Trials were included if they were placebo- or standard treatment-controlled, and if the treatment duration was at least 8 weeks. Relative risks and their 95% CIs were estimated with a random effects model.

RESULTS

Only 22 (43%) of 51 original reports contained information on the number of withdrawals and their causes. Missing information from the remaining 29 trials was obtained from the authors. The weighted mean duration of treatment was 100.2 weeks. After excluding administrative reasons, heart failure, myocardial infarction and hypertension, the withdrawal rates attributed to adverse events were 13.8% and 9.4% for the ACE inhibitor and control groups, respectively (RR = 1.54 [95% CI 1.30-1.83]; weighted difference = 3.1 per 100 treated patients [95% CI 1.8-4.4]). Cough, hypotension, renal dysfunction, dizziness, hyperkalaemia, and impotence were all significantly more prevalent among patients treated with ACE inhibitors than among those in the control groups.

CONCLUSIONS

Among patients with CHF or ventricular dysfunction enrolled in randomised clinical trials, treatment with an ACE inhibitor for an average of 2 years leads to an additional 3% of treatment withdrawals. In a significant proportion of the reports on these randomised clinical trials, information on adverse events leading to treatment withdrawal was inadequate. Proper evidence-based evaluation of the benefit/risk of therapeutic interventions needs a more systematic approach to reporting of adverse events experiences recorded in clinical trials.

Plasma concentrations of an angiotensin-converting enzyme inhibitor, benazepril, and its active metabolite, benazeprilat, after repeated administrations of benazepril in dogs with experimental kidney impairment

In order to examine the safety of an angiotensin-converting enzyme (ACE) inhibitor in dogs with impaired renal excretion route, benazepril was administered orally, and plasma concentrations of benazeprilat, the active metabolite of benazepril, were determined in dogs with renal mass reduction (1/4th kidney) created by right-side nephrectomy and ligation of branches of the left renal arteries. Five dogs were administered benazepril orally at a given dose (0.5 mg/kg body weight) and 4 other dogs received 20 times that dose (10 mg/kg body weight) once daily for 15 consecutive days before (intact kidney period) and after (1/4th kidney period) creation of kidney impairment. Six control dogs received surgical treatment, but no drug. After creating a 1/4th kidney, plasma urea nitrogen and creatinine concentrations increased to approximately 30 mg/dl and 2.0 mg/dl, respectively, and renal plasma flow and glomerular filtration rate decreased to 37% and 30% of pre-treatment values, respectively. However, these parameters did not change significantly during the 1/4th kidney period both in the 0.5 mg/kg and 10 mg/kg groups. In the 0.5 mg/kg group, plasma benazeprilat concentrations increased to approximately 20 ng/ml to 340 ng/ml 2 hr after each administration, and there were no significant differences between the plasma benazeprilat concentrations during the intact and 1/4th kidney periods. In the 10 mg/kg group, plasma benazeprilat concentrations varied in the individual dog, but did not increase with the days of administration, and were not significantly different on each administration day between the intact and 1/4th kidney periods in either dose group. The AUCs(0-24) of plasma benazeprilat concentrations determined on the 15th administration day were not different between the intact and 1/4th kidney periods in dogs of either dose group. Plasma ACE activities decreased after drug administration in dogs of both groups. Benazepril seemed to have a high safety, and the adjustment of dosage regimen might not be needed in dogs with mild to moderate renal function impairment because the drug was excreted both from the kidneys and liver.

Plasma angiotensin converting enzyme activity and pharmacokinetics of benazepril and benazeprilat in cats after single and repeated oral administration of benazepril.HCl

The plasma pharmacokinetics of benazepril and its active metabolite, benazeprilat, were determined in cats after oral administration of benazepril.HCl at dosages of 0.25, 0.5 and 1.0 mg/kg as a single dose (n = 5 per group) and after once daily application for 8 days (n = 6 per group). Pharmacodynamics were assessed by measurement of plasma angiotensin converting enzyme (ACE) activity. After single administration of benazepril.HCl, maximum benazepril concentrations were recorded at the first sample (2 h) and declined relatively rapidly with an elimination half life (t1/2) of 1.4 h. Highest benazeprilat concentrations were recorded at the first sample (2 h) in most cats and declined biphasically with half lives of each phase of 2.4 and 27.7 h. With repeated administration, plasma benazeprilat concentrations accumulated slightly with accumulation ratios (R) of 1.46, 1.36 and 1.24 for the 0.25, 0.5 and 1.0 mg/kg dosages of benazepril.HCl, respectively (median value of 1.36 for all dosages). All three dosages of benazepril.HCl caused marked inhibition of plasma ACE activity in all cats. The maximum effect (Emax, % inhibition of ACE as compared to baseline) was > or = 98% after single and 100% with repeated administration. The duration of action of benazepril.HCl was long, with > 87% (single) and > 90% (repeat) inhibition of plasma ACE persisting 24 h after dosing. Benazepril.HCl was well tolerated in all animals. Dosages of 0.25-1.0 mg/kg benazepril.HCl once daily are recommended for clinical testing in cats.

Pharmacokinetics of the angiotensin-converting-enzyme inhibitor, benazepril, and its active metabolite, benazeprilat, in dog

1. The pharmacokinetics of the angiotensin-converting-enzyme (ACE) inhibitor benazepril were evaluated in eight healthy Beagle dogs. Benazepril was administered orally at a dosage of 7.5 mg (about 0.5 mg/kg) both as a single dose and then once daily for 14 consecutive days. The prodrug, benazepril, and its active metabolite, benazeprilat, were measured in plasma using a gas chromatography mass-spectrometry method with mass-selective detection. 2. Benazepril appeared quickly in the plasma (tmax 0.5 h) and was rapidly eliminated by metabolism to benazeprilat. Peak benazeprilat concentrations were attained later (tmax 1.25 h) and declined biphasically with a rapid elimination phase (t1/2 lambda 1 1.1 and 1.7 h after single and the last repeated dose respectively) followed by a terminal elimination phase (t1/2 lambda z 11.7 and 19.0 h after single and repeated dose respectively). The mean residence time for benazeprilat was 15.2 h after the single dose and 17.4 h after the 14th dose. 3. Repeated administration of benazepril produced moderate bioaccumulation of benazeprilat; the ratio of AUC[0-->24 h]'s after the 14th dose as compared with the single dose was 1.47, equivalent to a half-life for accumulation (t1/2acc) of 14.6 h. Steady-state benazeprilat concentrations at peak (Cmax) and trough (Cmin) were reached within three doses. 4. The pharmacodynamics of benazepril were assessed by measurement of plasma ACE activity. After both single doses and at steady-state, benazepril produced inhibition of ACE activity in all dogs that was maximal at peak effect (Emax = 100%) and long-lasting (> 85% inhibition was present at 24 h). The long duration of action of benazepril on plasma ACE is due to the presence of the terminal elimination phase of benazeprilat, even though most of the metabolite is rapidly eliminated from the plasma.

Effects of once-daily benazepril therapy on exercise tolerance and manifestations of chronic congestive heart failure. The Benazepril Heart Failure Study Group

The effects of the long-acting angiotensin-converting enzyme inhibitor benazepril hydrochloride on exercise tolerance and signs and symptoms of congestive heart failure (CHF) were evaluated in a double-blind, multicenter, placebo-controlled clinical trial. Patients with chronic New York Heart Association class II to IV symptoms of CHF and an ejection fraction by radionuclide scanning of less than or equal to 35% were randomized in a 2:1 ratio to treatment with ascending doses of oral benazepril (n = 114) or placebo (n = 58) once daily, while continuing to receive background therapy with digoxin and diuretics. After randomization, patients were evaluated clinically every 2 weeks during a 12-week, double-blind treatment period. Maximal exercise tolerance was measured before and at specified time points after randomization by graded treadmill exercise testing. At week 12, mean exercise time increased 95 +/- 12 (SEM) seconds in the group receiving benazepril, whereas the increase was 37 +/- 18 seconds in the group receiving placebo (p less than 0.01 for the difference between the groups). There was also greater improvement in overall clinical status and in the signs and symptoms of CHF in benazepril-treated patients than in control subjects. There were 3 deaths in placebo-treated patients and none in benazepril-treated patients (p less than 0.05); the overall incidence of adverse effects was identical in the 2 groups. Benazepril is a well-tolerated angiotensin-converting enzyme inhibitor that provides clinically important improvement in exercise tolerance and in signs and symptoms when given once daily to patients with CHF receiving background therapy with digoxin and a diuretic.