Effects of zofenopril and ramipril on cough reflex responses in anesthetized and awake rabbits

Pathophysiology of cough with angiotensin-converting enzyme inhibitors: How to explain within-class differences?

Angiotensin converting enzyme inhibitors (ACEi) have consistently demonstrated improved survival and reduced risk of major cardiovascular events, across the spectrum of cardiovascular disease, including hypertension, coronary artery disease, myocardial infarction, and heart failure. The cardioprotective effects of ACEi result from inhibiting the conversion of angiotensin I to angiotensin II, and inhibition of bradykinin degradation. They are generally well tolerated but may cause the onset of a dry cough in some patients. This review presents current evidence on the incidence and mechanisms of cough associated with ACEi use, and then considers how to manage ACEi-related cough in clinical practice. The incidence of ACEi-induced cough in the published literature varies widely due to heterogeneity in the source data and lack of adequate controls. Incidence also varies among individual ACEi with agents such as perindopril, which has a high tissue ACE affinity, associated with a lower rate of cough. Evidence from real-world studies shows that the incidence of ACEi-associated cough is lower than rates reported in clinical trials. Patients who experience any dry cough are often switched to angiotensin- receptor blockers or other classes of antihypertensive drugs, regardless of cough severity. To avoid inappropriate discontinuation of ACEi in clinical practice, an alternative approach in patients with persistent cough is to perform a challenge/re-challenge to determine if re-introduction of ACEi is associated with recurrence of symptoms. Incidence of cough should not be considered a class effect for ACEi, and the patient may benefit by a switch from one ACEi to another. Every effort should be made to enable patients to continue ACEi therapy to reduce adverse cardiovascular outcomes and improve survival.

The effect of stimulation and unloading of baroreceptors on cough in experimental conditions

Cough, the main airway defensive process, is modulated by multiple sensory inputs from the respiratory system and outside of it. This modulation is one of the mechanisms that contributes to the sensitization of cough pathways at the peripheral and/or central level via neuroplasticity and it manifests most often as augmented coughing. Cardiorespiratory coupling is an important mechanism responsible for a match between oxygenation and cardiac output and bidirectional relationships exist between respiration and cardiovascular function. While the impact of cough with the robust swings of the intrathoracic pressure on haemodynamic parameters and heart electrophysiology are well characterized, little is known about the modulation of cough by haemodynamic parameters - mainly the blood pressure. Some circumstantial findings from older animal studies and more recent sophisticated analysis confirm that baroreceptor stimulation and unloading alters coughing evoked in experiments. Clinical relevance of such findings is not presently known.

Zofenopril versus ramipril in the early phase of acute myocardial infarction with systolic dysfunction: A retrospective study

Introduction:

Prognostic benefits of zofenopril over ramipril in the early phase of acute myocardial infarction have been reported by the SMILE study, but these benefits have not been tested in clinical practice in the Chinese population. The objective of this study was to compare the effectiveness and safety of zofenopril plus aspirin against ramipril plus aspirin in patients with acute myocardial infarction.

Methods:

Patients in the early phase of acute myocardial infarction received 30 mg zofenopril (ZF cohort, N=191) or 5 mg ramipril (RP cohort, N=256) b.i.d. plus 100 mg aspirin/day. Data regarding hospitalisation for cardiovascular disease, non-cardiovascular events and mortality were collected and analysed.

Results:

During 1 year of treatment, 47 (25%) patients in the ZF cohort and 97 (40%) patients in the RP cohort were hospitalised due to cardiovascular disease (p=0.002), and three (2%) patients in the ZF cohort and 14 (6%) patients in the RP cohort died (p=0.043). Lower incidences of dry cough (p=0.001) and anaemia (p=0.049) were reported in the ZF cohort.

Conclusions:

The study recommends zofenopril with 100 mg aspirin for a longer period in patients with acute myocardial infarction with systolic dysfunction.

Zofenopril and Ramipril in Combination with Acetyl Salicylic Acid in Postmyocardial Infarction Patients with Left Ventricular Systolic Dysfunction: A Retrospective Analysis of the SMILE-4 Randomized, Double-Blind Study in Diabetic Patients

OBJECTIVE

In the SMILE-4 study, zofenopril + acetyl salicylic acid (ASA) was more effective than ramipril + ASA on 1-year prevention of major cardiovascular events (MACE) in patients with acute myocardial infarction complicated by left ventricular dysfunction. In this retrospective analysis, we evaluated drug efficacy in subgroups of patients, according to a history of diabetes mellitus.

METHODS

The primary study endpoint was 1-year combined occurrence of death or hospitalization for cardiovascular causes. Diabetes was defined according to medical history (previous known diagnosis).

RESULTS

A total of 562 of 693 (81.0%) patients were classified as nondiabetics and 131 (18.9%) as diabetics. The adjusted rate of MACE was lower under zofenopril than under ramipril in both nondiabetics [27.9% vs. 34.9% ramipril; odds ratio, OR and 95% confidence interval: 0.55 (0.35, 0.86)] and diabetics [30.9% vs. 41.3%; 0.56 (0.18, 1.73)], although the difference was statistically significant only for the nondiabetic group (P = 0.013). Zofenopril was superior to ramipril as regards to the primary study endpoint in the subgroup of 157 patients with uncontrolled blood glucose (≥ 126 mg/dL), regardless of a previous diagnosis of diabetes [0.31 (0.10, 0.90), P = 0.030]. Zofenopril significantly reduced the risk of hospitalization for cardiovascular causes in both nondiabetics [0.64 (0.43, 0.96), P = 0.030] and diabetics [0.38 (0.15, 0.95), P = 0.038], whereas it was not better than ramipril in terms of prevention of cardiovascular deaths.

CONCLUSIONS

This retrospective analysis of the SMILE-4 study confirmed the good efficacy of zofenopril plus ASA in the prevention of long-term MACE also in the subgroup of patients with diabetes mellitus.

Pharmacology of Bradykinin-Evoked Coughing in Guinea Pigs

Bradykinin has been implicated as a mediator of the acute pathophysiological and inflammatory consequences of respiratory tract infections and in exacerbations of chronic diseases such as asthma. Bradykinin may also be a trigger for the coughing associated with these and other conditions. We have thus set out to evaluate the pharmacology of bradykinin-evoked coughing in guinea pigs. When inhaled, bradykinin induced paroxysmal coughing that was abolished by the bradykinin B2 receptor antagonist HOE 140. These cough responses rapidly desensitized, consistent with reports of B2 receptor desensitization. Bradykinin-evoked cough was potentiated by inhibition of both neutral endopeptidase and angiotensin-converting enzyme (with thiorphan and captopril, respectively), but was largely unaffected by muscarinic or thromboxane receptor blockade (atropine and ICI 192605), cyclooxygenase, or nitric oxide synthase inhibition (meclofenamic acid and N(G)-nitro-L-arginine). Calcium influx studies in bronchopulmonary vagal afferent neurons dissociated from vagal sensory ganglia indicated that the tachykinin-containing C-fibers arising from the jugular ganglia mediate bradykinin-evoked coughing. Also implicating the jugular C-fibers was the observation that simultaneous blockade of neurokinin2 (NK2; SR48968) and NK3 (SR142801 or SB223412) receptors nearly abolished the bradykinin-evoked cough responses. The data suggest that bradykinin induces coughing in guinea pigs by activating B2 receptors on bronchopulmonary C-fibers. We speculate that therapeutics targeting the actions of bradykinin may prove useful in the treatment of cough.

The cough reflex is upregulated by lisinopril microinjected into the caudal nucleus tractus solitarii of the rabbit

We have previously shown that cough potentiation induced by intravenous administration of the AT1 receptor antagonist losartan is lower than that induced by the ACE inhibitor lisinopril in anesthetized and awake rabbits. Since losartan and lisinopril cross the blood-brain barrier, their central action on the cough reflex can be hypothesized. Mechanical stimulation of the tracheobronchial tree and citric acid inhalation were used to induce cough reflex responses in pentobarbital sodium-anesthetized, spontaneously breathing rabbits. Bilateral microinjections (30-50 nl) of losartan (5mM), lisinopril (1mM), bradykinin (0.05 mM), HOE-140 (0.2mM, a bradykinin B2 receptor antagonist) and CP-99,994 (1mM, an NK1 receptor antagonist) were performed into the caudal nucleus tractus solitarii, the predominant site of termination of cough-related afferents. Lisinopril, but not losartan increased the cough number. This effect was reverted by HOE-140 or CP-99,994. Cough potentiation was also induced by bradykinin. The results support for the first time a central protussive action of lisinopril mediated by an accumulation of bradykinin and substance P.

A crossover randomized comparative study of zofenopril and ramipril on cough reflex and airway inflammation in healthy volunteers

BACKGROUND

Persistent dry cough is a well known unwanted effect of Angiotensin-Converting Enzyme inhibitors (ACE-i). Animal studies have shown that the ACE-i zofenopril has a less tussigenic effect compared to the widely used ACE-i ramipril. The aim of this study was to compare cough sensitivity to inhaled tussigens, as well as spontaneous cough in response to the administration of zofenopril and ramipril in healthy volunteers; pharmacokinetic (PK) data of both zofenopril and ramipril, as well as their respective active forms, zofenoprilat and ramiprilat, was also collected.

METHODS

Forty healthy volunteers were enrolled in a randomized crossover study. Patients were administered zofenopril calcium salt (test drug) coated tablets, 30 mg daily dose or ramipril (reference drug) tablets, 10 mg daily dose, for 7 consecutive days in two periods separated by a 21-day wash-out period. Cough sensitivity to capsaicin and citric acid was assessed as the concentration of each tussigenic agent causing at least 2 (C2) or 5 coughs (C5); spontaneous cough was also monitored throughout the study. PK parameters of zofenopril, ramipril and their active forms, were collected for each of the two study periods. Airway inflammation, as assessed by fractional exhaled nitric oxide (FeNO) and bradykinin (BK) levels, were measured prior to and following each treatment period.

RESULTS

Ramipril, but not zofenopril, increased (p < 0.01) cough sensitivity to both tussigenic agents as assessed by C2. With citric acid, C5 values calculated after both ramipril and zofenopril administration were significantly (p < 0.05 and p < 0.01, respectively) lower than corresponding control values. With both ACE-i drugs, spontaneous cough was infrequently reported by subjects. Zofenopril/zofenoprilat PK analysis showed higher area under the curve of plasma concentration, τ values (ng/ml x h) than ramipril/ramiprilat (zofenopril vs. ramipril, 84.25 ± 34.47 vs. 47.40 ± 21.30; and zofenoprilat vs. ramiprilat, 653.67 ± 174.91 vs. 182.26 ± 61.28). Both ACE-i drugs did not affect BK plasma levels; in contrast, ramipril, but not zofenopril, significantly increased control FeNO values (from 24 ± 9.6 parts per billion [PPB] to 33 ± 16 PPB; p < 0.01).

CONCLUSIONS

Zofenopril has a more favourable profile when compared to ramipril as shown by a reduced pro-inflammatory activity and less impact on the cough reflex.

Zofenopril and ramipril and acetylsalicylic acid in postmyocardial infarction patients with left ventricular systolic dysfunction: a retrospective analysis in hypertensive patients of the SMILE-4 study

BACKGROUND

Antecedent hypertension represents a risk factor for adverse outcomes in survivors of acute myocardial infarction (AMI). Prognosis of such patients might be greatly improved by drugs enhancing blood pressure control. In the present retrospective analysis of the randomized, double-blind, parallel-group, SMILE-4 study we compared the efficacy of zofenopril 60 mg and acetylsalicylic acid (ASA) 100 mg versus ramipril 10 mg and ASA in patients with AMI complicated by left ventricular dysfunction, classified according to a history of hypertension.

METHODS

The primary study end-point was 1-year combined occurrence of death or hospitalization for cardiovascular causes. Hypertension was defined according to medical history and current blood pressure values at entry and could be determined in 682 of 716 patients of the intention-to-treat analysis.

RESULTS

One hundred and fifty-seven patients (23%) were normotensives and 525 (77%) hypertensives. In the normotensive population the primary end-point occurred in 19 of 76 zofenopril-treated patients (25%) and in 23 of 81 ramipril-treated patients (28%) [odds ratio (95% confidence interval): 0.84 (0.41-1.71), P = 0.631]. In the hypertensive population, major cardiovascular outcomes were reported in 84 of 273 zofenopril-treated patients (31%) and in 99 of 252 ramipril-treated patients (39%), with a 31% significantly (P = 0.041) lower risk with zofenopril [0.69 (0.48-0.99)]. The superiority of zofenopril versus ramipril was particularly evident in patients with isolated systolic hypertension [n = 131, 0.48 (0.23-0.99), P = 0.045].

CONCLUSION

This retrospective analysis of the SMILE-4 study confirmed the good efficacy of zofenopril and ASA in the prevention of long-term cardiovascular outcomes also in the subgroup of patients with hypertension.

Comparison between zofenopril and ramipril in combination with acetylsalicylic acid in patients with left ventricular systolic dysfunction after acute myocardial infarction: results of a randomized, double-blind, parallel-group, multicenter, European study (SMILE-4)

BACKGROUND

Angiotensin-converting enzyme inhibitors (ACEIs) are largely employed for treating patients with left ventricular dysfunction (LVD), but their efficacy may be negatively affected by concomitant administration of acetylsalicylic acid (ASA), with some difference among the different compounds.

HYPOTHESIS

The interaction between ASA and the two ACEIs zofenopril and ramipril may result in a different impact on survival of cardiac patients, due to differences in the pharmacological properties of the two ACEIs.

METHODS

This phase IIIb, randomized, double-blind, parallel-group, multicenter, European study compared the safety and efficacy of zofenopril (60 mg/day) and ramipril (10 mg/day) plus ASA (100 mg/day), in 771 patients with LVD (clinical signs of heart failure or a left ventricular ejection fraction <45%) following acute myocardial infarction (AMI). The primary study end point was 1-year combined occurrence of death or hospitalization for cardiovascular causes.

RESULTS

In the intention-to-treat population, the primary outcome was significantly reduced by zofenopril (n = 365) vs ramipril (n = 351) (odds ratio [OR]: 0.70, and 95% confidence interval [CI]: 0.51-0.96; P = 0.028) as a result of a decrease in cardiovascular hospitalization (OR: 0.64,95% CI: 0.46-0.88; P = 0.006). Mortality rate was not significantly different between the 2 treatments (OR: 1.51, 95% CI: 0.70-3.27; P = 0.293). Blood pressure values did not significantly change during the 1-year follow-up. N-terminal pro-brain natriuretic peptide levels were progressively reduced during the study, with no statistically significant between-treatment differences. Proportion of patients with deterioration of renal function during the study was similar between the 2 groups. Drug safety profile was comparable between treatments.

CONCLUSIONS

In patients with LVD following AMI, the efficacy of zofenopril associated with ASA was superior to that of ramipril plus ASA, indicating some important clinical implications for the future use of ACEIs in patients with LVD or overt heart failure.

Zofenopril and incidence of cough: a review of published and unpublished data

OBJECTIVE

Cough is a typical side effect of angiotensin-converting enzyme (ACE) inhibitors, though its frequency quantitatively varies among the different compounds. Data on the incidence of cough with the lipophilic third-generation ACE inhibitor zofenopril are scanty and never systematically analyzed. The purpose of this paper is to give an overview on the epidemiology, pathophysiology, and treatment of ACE inhibitor-induced cough and to assess the incidence of cough induced by zofenopril treatment.

METHODS

Published and unpublished data from randomized and postmarketing zofenopril trials were merged together and analyzed.

RESULTS

Twenty-three studies including 5794 hypertensive patients and three studies including 1455 postmyocardial infarction patients exposed for a median follow-up time of 3 months to zofenopril at doses of 7.5-60 mg once-daily were analyzed. The incidence of zofenopril-induced cough was 2.6% (range 0%-4.2%): 2.4% in the hypertension trials (2.4% in the double-blind randomized studies and 2.4% in the open-label postmarketing studies) and 3.6% in the doubleblind randomized postmyocardial infarction trials. Zofenopril-induced cough was generally of a mild to moderate intensity, occurred significantly (P < 0.001) more frequently in the first 3-6 months of treatment (3.0% vs 0.2% 9-12 months), and always resolved or improved upon therapy discontinuation. Zofenopril doses of 30 mg and 60 mg resulted in significantly (P = 0.042) greater rate of cough (2.1% and 2.6%, respectively) than doses of 7.5 mg and 15 mg (0.4% and 0.7%, respectively). In direct comparison trials (enalapril and lisinopril), incidence of cough was not significantly different between zofenopril and other ACE inhibitors (2.4% vs 2.7%).

CONCLUSION

Evidence from a limited number of studies indicates a relatively low incidence of zofenopril-induced cough. Large head-to-head comparison studies versus different ACE inhibitors are needed to highlight possible differences between zofenopril and other ACE inhibitors in the incidence of cough.