Efficacy of felodipine in chronic congestive heart failure: a placebo controlled haemodynamic study at rest and during exercise and orthostatic stress

Tilting-Induced Decrease in Systolic Blood Pressure in Bedridden Hypertensive Elderly Inpatients: Effects of Azelnidipine

The object of this study was to examine blood pressure (BP) variability due to postural change in elderly hypertensive patients. The subjects studied were 154 elderly inpatients in a hospital for the elderly (48 male and 106 female; median age: 82 years), consisting of age- and sex-matched bedridden (n=39) and non-bedridden (n=39) normotensive controls and bedridden (n=38) and non-bedridden (n=38) hypertensive patients. BP and pulse rate (PR) were measured in the supine position, then again after a 2-min, 45 deg head-up tilt with the legs horizontal. The decrease in systolic BP (SBP) on tilting in the bedridden hypertensive group (median: -10 mmHg; range: -32 to 9 mmHg) was significantly (p<0.008) greater than those in the other three groups. Monotherapy with azeinidipine, a long-acting calcium channel blocker, for 3 months not only significantly reduced the basal BP and PR of hypertensive patients in the two groups, but also significantly (p<0.05) attenuated the tilt-induced decrease in the SBP to -3 mmHg (-19 to 25 mmHg) and enhanced the change in PR from -1 bpm (-10 to 7 bpm) to 1 bpm (-4 to 23 bpm) in the bedridden hypertensive group. Our findings indicate that tilt-induced decrease in SBP is a rather common phenomenon in bedridden elderly hypertensive patients, and that treatment with azelnidipine attenuates tilt-induced decrease in SBP, probably through an improvement of baroreceptor sensitivity.

Vascular selective calcium entry blockers in the treatment of cardiovascular disorders: focus on felodipine

Calcium entry through L-type calcium channels is essential for contraction of both arterial smooth muscle and the myocardium, and is important in cardiac conduction. First-generation calcium entry blockers lack or have a modest degree of vascular selectivity and inhibit cardiac function at doses producing therapeutic arterial dilatation. Such agents may cause deterioration in patients with left ventricular dysfunction, and their combination with a beta-adrenergic blocker may adversely affect cardiac contractility and conduction. Development of newer agents has focused on obtaining a higher degree of vascular selectivity. Felodipine is a highly vascular selective calcium entry blocker, with a vascular selectivity ratio greater than 100, as shown experimentally. Isradipine and nicardipine are also vascularly selective calcium entry blockers. Hemodynamic studies in patients with hypertension, coronary artery disease, congestive heart failure, or in patients receiving beta-adrenergic blockade, show that felodipine can produce profound arteriolar dilatation without the negative effects of left ventricular systolic performance. Furthermore, felodipine alone or when added to a beta-adrenergic blocker does not interfere with cardiac conduction. The primary mechanism that accounts for the efficacy of dihydropyridine calcium entry blockers in hypertension and angina pectoris is arterial dilation, whereas nondihydropyridines may also derive part of their effect from inhibition of cardiac performance. As some of these patients, most commonly the elderly, have concomitant left ventricular dysfunction, it should be advantageous to avoid myocardial depression in the treatment of their primary disease. Preliminary studies in patients with heart failure indicate that felodipine and amlopidine may improve hemodynamics, reduce neurohormonal activation, and increase exercise tolerance, but final conclusions must await the randomized clinical trials now underway.

Placebo controlled trial of felodipine in patients with mild to moderate heart failure. UK Study Group

OBJECTIVE

To compare the effects of felodipine and placebo in patients with New York Heart Association functional class II or III and stable congestive heart failure despite treatment with an angiotensin converting enzyme inhibitor, diuretic, or digoxin, or any combination of these three drugs.

PATIENTS AND DESIGN

252 patients were randomised in a double blind, parallel group study after a 2-4 week placebo run-in to oral treatment with either felodipine extended release formulation or placebo 2.5-10 mg twice daily given in addition to existing background medication for a further 12 weeks.

METHODS

Patients aged 18-75 years of either sex with chronic congestive heart failure due to ischaemic heart disease, hypertensive heart disease, or dilated cardiomyopathy with or without secondary mitral insufficiency that was stable during the preceding two months were included in the study. Treadmill exercise tests according to the modified Naughton protocol were performed at baseline, and after six, 11, and 12 weeks of treatment. Signs and symptoms of heart failure were assessed at every visit. Physical examination was performed and left ventricular ejection fraction measured at baseline and after 12 weeks.

RESULTS

Mean (SD) baseline exercise test times increased from 434 (162) s and 480 (157) s for felodipine and placebo groups respectively to 541 (217) s and 591 (218) s at 12 weeks or the last visit. The change in exercise from baseline to last visit was 107 (141) s for patients given felodipine and 112 (128) s for those given placebo (P > 0.20). There was also no difference between treatments with respect to the other efficacy variables. There were few deaths in the study (felodipine n = 3, placebo n = 2). More patients who received felodipine were withdrawn from treatment (n = 29) than those who received placebo (n = 17). The most common adverse events of the 54 and 28 cited as reasons for withdrawal in the felodipine and placebo groups respectively were increased need for non-study heart failure treatment (n = 10; 8%)--that is, starting new medication or changes in the dosage of existing treatment for patients given felodipine, and nausea (n = 4; 3%) for those given placebo. Patients withdrawn from the study due to increased need for non-study heart failure treatment rapidly stabilised and recovered.

CONCLUSION

Felodipine has not been shown to be of benefit in patients with mild to moderate heart failure.

Efficacy of vasodilators in the treatment of heart failure

Vasodilator drugs have been undergoing evaluation as therapy for heart failure for > 20 years. It has become clear that hemodynamic benefits, short-term improvement in exercise tolerance and long-term alteration in mortality are independent end points for efficacy of these drugs. Differing hemodynamic responses, variable effects on exercise capacity and differential effect on mortality of various vasodilator compounds raise the likelihood that vascular smooth muscle relaxation is not the sole mechanism of action of these drugs. Neurohormonal and antiproliferative effects of these agents may play a key role in the long-term response. Data from trials indicate that the vasodilator combination of hydralazine and isosorbide dinitrate as well as converting enzyme inhibitors can favorably affect all end points. The global efficacy of other vasodilators, such as calcium antagonists, has not yet been fully evaluated.

Hypertension in the elderly: age- and disease-related complications and therapeutic implications

Effective treatment of hypertension in the elderly requires an understanding of both the progressive course of the disease and the impact of aging on the cardiovascular system, including physiological, genetic, lifestyle, and environmental factors. Review of the literature that has attempted to define the impact of an "aging process" on cardiovascular structure and function reveals a diversity of findings and interpretations. However, in general, normotensive elderly subjects exhibit the heart and vascular characteristics of "muted" hypertension, including many features of younger hypertensive patients: cardiac hypertrophy, diminution in resting left ventricular early diastolic filling rate, increased arterial stiffness and aortic impedance, diminution in the baroreceptor reflex, a diminished response to catecholamines and diminished renal blood flow, and an increase in peripheral vascular resistance (PVR). Treatment of elderly hypertensives is more challenging because of the greater likelihood of the presence of concomitant diseases, most importantly, coronary and peripheral atherosclerosis, renal dysfunction, and diabetes mellitus. Isolated systolic hypertension (ISH), the most common form of hypertension in the elderly, has also been clearly shown to be an important predictor of cardiovascular morbidity and mortality, including coronary artery disease, congestive heart failure, and stroke. Treatment of ISH has been shown to lower systolic pressure safely and effectively in the elderly. By reducing PVR, and possibly the arterial stiffness, and thus the early reflected pulse waves, vasodilators, including calcium antagonists, may lower these three components of arterial impedance, and hence lower the arterial load on the heart. The cardiac hypertrophy and reduced left ventricular filling rate associated with hypertension in older individuals can also be ameliorated, to some extent, by calcium channel blockers.

Treatment of hypertension with felodipine in patients with concomitant diseases

Coexisting medical conditions often complicate the selection of antihypertensive drugs. Felodipine, a new vascular-selective calcium antagonist with demonstrated antihypertensive efficacy, has not been found to alter lipid profiles in hypertensive patients. Studies in additional patient populations have yielded insights into the effects of the drug on other diseases that may coexist with hypertension. In individuals with stable angina pectoris or congestive heart failure, acute administration of felodipine reduces systemic vascular resistance and increases cardiac output and total coronary blood flow; myocardial contractility is not depressed at doses that produce a clinically significant reduction in vascular resistance. In patients with coronary stenoses, the drug increases vessel diameter in the vicinity of obstructive lesions. Single-dose and long-term studies in patients with exertional angina have found that felodipine reduces anginal frequency and improves exercise tolerance. In patients with congestive heart failure, chronic dosing with felodipine produces a persistent reduction in vascular resistance and an increase in cardiac output, both at rest and during exercise. Symptomatic improvement and increased exercise tolerance have been noted in some studies. In patients with Raynaud's phenomenon, felodipine has been associated with a dose-dependent improvement in symptomatology. Among individuals with exercise-induced bronchospasm, the drug has no effect on resting bronchial tone and may exert some positive effects during exercise. In hypertensive patients with Type II diabetes, felodipine has not been found to raise glucose levels significantly. The data obtained thus far suggest that felodipine is safe for use in hypertensive patients with a variety of concomitant diseases.

Felodipine clinical pharmacokinetics

Absorption of felodipine is rapid and complete. A pronounced first-pass metabolism results in a bioavailability of 15%, irrespective of the oral formulation used. The peak plasma concentrations and area under the plasma concentration-time curve are linearly related to the dose. The variability in plasma concentrations is wide, and individualization of the dosage is recommended. Plasma felodipine concentrations are increased in the elderly, and in patients with congestive heart failure or liver cirrhosis; in these patients felodipine should be started at a low dosage. Food intake has no clinically significant effect on felodipine absorption. Serum digoxin concentrations are increased by felodipine in plain tablet form, but not when it is administered as extended release tablets. Activators, inducers and inhibitors of the cytochrome P450 system affect the plasma concentrations of felodipine. No displacement reactions with high affinity protein binding drugs have been observed. There is a significant correlation between plasma concentration and haemodynamic effect. The mean elimination half-life of 24h together with the extended release formulation of felodipine favours once-daily dosage in patients with hypertension.

Felodipine: a new dihydropyridine calcium-channel antagonist

Felodipine, a dihydropyridine calcium-channel antagonist, significantly reduces systolic and diastolic blood pressure (BP) in patients with hypertension and has been associated with beneficial hemodynamic effects in patients with chronic stable angina pectoris or congestive heart failure (CHF). In hypertensive patients, felodipine does not appear to significantly affect glomerular filtration rate, creatinine clearance, glucose tolerance, or plasma lipoprotein concentrations. Studies comparing felodipine with other agents as monotherapy in mild to moderate hypertension have demonstrated felodipine to be at least as efficacious as hydrochlorothiazide (HCTZ) and HCTZ plus amiloride hydrochloride in combination. Comparisons of felodipine with other agents as adjuncts to beta-blocker or diuretic therapy have shown felodipine to be at least as effective as HCTZ, propranolol hydrochloride, prazosin hydrochloride, and nifedipine. Evaluations of patients with chronic stable angina are limited, and additional studies are needed before felodipine can be recommended for the routine management of angina pectoris. Similarly, additional studies are essential to delineate the role of felodipine, if any, in the management of CHF. In the management of hypertension, felodipine 5-40 mg/d significantly reduces systolic and diastolic BP. Although some patients may be controlled throughout the entire dosing interval when felodipine is administered bid, many patients will require more frequent dosing to obtain adequate BP control. Adverse effects associated with felodipine are similar to those of other dihydropyridine calcium-channel antagonists and include peripheral edema, headache, dizziness, flushing, and fatigue. A potentially clinically important drug interaction was observed when felodipine was administered concomitantly with theophylline aminopropanol; significant decreases in theophylline concentrations were noted. In summary, felodipine appears to be safe and effective for the management of hypertension when used alone or in combination with other antihypertensive agents. The efficacy of felodipine in the management of chronic stable angina pectoris and CHF requires further investigation.

Calcium antagonists in patients with heart failure. A review

The presence of calcium ions is essential to the normal function of the cardiovascular system. Drugs such as calcium antagonists can modulate the interaction between these ions and specific cells at different levels, interfering with myocardial contraction and relaxation, vascular tone, specific conduction tissues and neuromuscular function. Vascular beds play a crucial role in adjustment of myocardial function to different body oxygen requirements; compensatory mechanisms in congestive heart failure (CHF) involve the vascular system to a large extent and paradoxically may worsen myocardial performance. Vasodilating drugs represent an important step forward in achieving better symptomatic results in CHF patients, and may also increase their survival. Of the different classes of vasodilator drugs calcium antagonists may represent an attractive alternative due to their anti-ischaemic and antiarrhythmic effects. Despite the overall good response to the acute use of these drugs in CHF, long term studies in which first generation calcium antagonists (nifedipine, diltiazem, verapamil) were used have produced disappointing results. Their main drawbacks were negative inotropism, lack of preload reduction and activation of neurohormonal mechanisms with a subsequent adverse effect on cardiovascular function, the latter effect being the most significant. A few long term studies, of between 1 and 52 months, have not demonstrated a consistent improvement in functional class in spite of apparently good initial results. The second generation of calcium antagonists have more potent and selective vasodilating properties with less negative inotropic effects; these properties might justify their use in the therapy of CHF, but no clear recommendations can be given due to the lack of large, long-term, controlled studies. Overall, the existing clinical trials with calcium antagonists in CHF have not proved the superiority of this group of drugs when compared to other vasodilators. If the aetiology of CHF is related to the presence of coronary artery disease or arterial hypertension, calcium antagonists might be considered as additional therapeutic options. Diastolic dysfunction may be corrected or improved and coronary tone may be diminished, both of which may lead to a better myocardial oxygen supply. Systolic myocardial function must be evaluated in CHF patients before starting therapy with calcium antagonists in order to avoid possible deleterious effects. Further studies may shed more light on this matter and may indicate decisively whether or not calcium antagonists should play a role in the therapeutic pharmacological arsenal of selected CHF patients.

Acute and chronic efficacy of felodipine in congestive heart failure

In 13 patients with congestive heart failure we tested the acute hemodynamic effects of 5 vs. 10 mg felodipine tablets, in a double-blind, cross-over study. One hour after felodipine 5 mg, echocardiographic ejection fraction (%), cardiac index (thermodilution-ml/min/m2), and pulmonary wedge pressure (mm Hg) significantly changed (from 21 +/- 2 to 26 +/- 2, 2350 +/- 150 to 2790 +/- 160, 24 +/- 4 to 17 +/- 4) while they remained steady after felodipine 10 mg. The greatest stroke index increases were associated with felodipine 5 mg in 12 patients and 10 mg in 1 patient. Therefore we evaluated (open study) the long-term (2 months- 1 year) clinical and hemodynamic efficacy following the treatment with the acutely most effective dose (twice daily). After 2 months ejection fraction, cardiac index and pulmonary wedge pressure were respectively 24 +/- 2, 2550 +/- 150, and 18 +/- 4 (12 hours after the last drug administration, n = 11, P less than 0.02 from baseline). These parameters further increased one to two hours after the following administration of felodipine. Clinical improvement (reduction of 1 functional class, according to the New York Heart Association) was observed in 8/13 patients. These 8 patients participated to the one year follow-up. In 5 patients follow-up was interrupted because of acute cardiovascular events. However, before study interruption (5 patients) or ending (3 patients) clinical status did not worsen and ejection fraction remained higher than in the pretreatment period. Therefore, low dose felodipine might be used in the treatment of congestive heart failure.

Behavioral effects of chronic, orally administered diuretic and verapamil in baboons

Behavioral performances of six baboons were tested during chronic oral dosing with diuretic (hydrochlorothiazide/triamterene), a calcium channel blocker (verapamil), and a combination of the two drugs. Reaction times and color matching-to-sample performances as well as physiological measures were obtained in deoxycorticosterone acetate (DOCA)-salt baboons and in renovascular hypertensive baboons. Combined diuretic and verapamil impaired color matching to a small degree in comparison to baseline performance, while drug administered alone had no effect. Weekly systolic and diastolic blood pressures decreased maximally from baseline during the drug combination period, and were accompanied by maximal increases in serum sodium. The largest behavioral impairments during combination dosing were observed for colors that were most difficult to discriminate during baseline. Significant positive correlations were found between systolic blood pressure and color matching accuracy. No differences between the animal hypertension groups were found as a function of drug condition either in physiological or behavioral responses. Only the combination of diuretic and verapamil produced a deleterious effect on color discrimination, which suggests further study of commonly administered drug combination therapies in hypertension.

Felodipine in severe chronic congestive heart failure: acute effects on central hemodynamics and regional blood flow distribution

In order to assess the effect of felodipine, a new calcium antagonist with vascular selectivity, on regional blood flow distribution at rest in chronic congestive heart failure, ten patients were studied during an acute test. Right heart catheterization allowed the evaluation of hemodynamic parameters; renal blood flow was calculated using paraamino-hippuric acid clearance; hepatic blood flow measurement was based on indocyanine green clearance; and limb blood flow was assessed with venous occlusion plethysmography. Blood samples were collected for the analysis of plasma catecholamines, renin, and aldosterone. All parameters were recorded in duplicate under basal conditions and after felodipine infusion. The infusion of felodipine induced a significant increase in cardiac index, stroke work index, and limb blood flow. Systemic and pulmonary arterial blood pressure, pulmonary wedge pressure, and systemic resistance underwent a significant decrease. The heart rate, pulmonary resistance, renal blood flow, and hepatic blood flow were not changed. In conclusion, felodipine was of benefit in congestive heart failure at rest in an acute test, acting through a marked decrease in vascular resistance and a consequent improvement in cardiac output and limb blood flow. No changes in renal and hepatic blood flow were observed.

Pharmacokinetics of felodipine after intravenous and chronic oral administration in patients with congestive heart failure

1. In a randomized, parallel, double-blind study felodipine was administered to 11 and placebo to 12 patients with congestive heart failure. The kinetics of felodipine were studied after acute intravenous administration and after chronic oral treatment for 8 weeks. The relationship between cardiac output and pharmacokinetics was analyzed. The pharmacokinetic data were compared with data from young healthy individuals and hypertensive patients. 2. After oral therapy, significant correlations were found between cardiac output and AUC and systemic bioavailability (F). Furthermore, cardiac output before therapy was also significantly correlated with absorption characteristics. No relationship could be demonstrated between cardiac output and i.v. pharmacokinetics. A comparison of patients with heart failure and young healthy individuals revealed that the AUC was three times higher in heart failure patient, while Vss and the ratio of the AUC of the pyridine metabolite to that of felodipine were similar. Oral clearance was reduced by 50% and the terminal half-life was concomitantly increased. Pharmacokinetic data for felodipine are similar in patients with heart failure to published data from elderly hypertensive patients. 3. An increase in liver blood flow during chronic oral therapy, induced by felodipine itself, appears to explain an increase in bioavailability and thus to higher plasma drug concentrations. Thus, it is advisable to start felodipine treatment at a low dosage in patients with congestive heart failure.

Oral pharmacokinetics of felodipine in patients with congestive heart failure: variable prediction using intravenous data

Peak and trough concentrations after 8 weeks oral therapy with felodipine, a vasodilating calcium antagonist of the dihydropyridine group, were predicted from intravenous pharmacokinetic data before therapy in 11 patients, randomly allocated to felodipine treatment 10 mg b.i.d., during a placebo controlled study in patients with congestive heart failure. Peak concentrations were well predictable, but trough levels varied between a good agreement in some patients to a large underestimation in others. Predictability was significantly correlated with half life, plasma clearance and distribution volume of the intravenous pharmacokinetic study. After 8 weeks chronic oral therapy no significant differences could be detected between the oral pharmacokinetics of predictable (n = 6) and unpredictable (n = 5) patients. This demonstrates that felodipine kinetics change during felodipine treatment. Differences in the distribution of blood flow before therapy combined with an interindividual variability in blood flow response during therapy is probably responsible for the observed impossibility to calculate trough levels, and thus oral dosage schedules, from intravenous pharmacokinetic data in patients with congestive heart failure.

Vasodilator therapy without converting-enzyme inhibition in congestive heart failure--usefulness and limitations

Despite a well-established rationale for pharmacologically induced arterial and venous vasodilatation in congestive heart failure, the clinical usefulness of long-term vasodilator therapy without concomitant converting-enzyme inhibition generally has been disappointing. With the exception of nitrates and, possibly, the combination of nitrates and hydralazine, the use of converting-enzyme inhibitors in many aspects appears preferable in the majority of patients. This article reviews the pathophysiology of inappropriate vasoconstriction in heart failure, the cellular mode of action of the various vasodilators, hemodynamic effects with respect to the peripheral site of action, clinical usefulness and limitations of different vasodilators, and the various determinants of clinical efficacy. Finally, an attempt is made to assess when and how to introduce vasodilator treatment with and without concomitant ACE inhibition.

The effects of treatment with felodipine as a single agent in coronary artery disease

In an earlier study one dose of the vasodilator felodipine improved haemodynamic function in patients with angina without having a negative inotropic effect. The haemodynamic response of sustained treatment with felodipine as a single agent in stable angina was investigated in a double blind crossover study of 25 patients. The dosage of felodipine was increased from 5 mg twice daily to 10 mg twice daily after two weeks. Twenty one patients completed the study, two were withdrawn because of acute myocardial infarction, and a further two because of symptoms of vasodilatation. Felodipine reduced both supine and erect blood pressure and increased the resting heart rate. Median exercise time was increased by 10% at two weeks and 7% at four weeks. There was a sustained reduction in the number of angina attacks and use of sublingual nitrate on active treatment. Felodipine has antianginal effects but these are limited and seem less than those of other related compounds. This finding is unexpected and possibly related to increased heart rate.

Felodipine. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in hypertension

Felodipine is a dihydropyridine calcium antagonist which selectively relaxes vascular smooth muscle. By acting at peripheral arterioles, it lowers systemic vascular resistance and thereby produces substantial decreases in blood pressure and increases in cardiac output. Felodipine is indicated for the management of hypertension, and in patients with mild to moderate disease felodipine monotherapy markedly lowers blood pressure. It proved as effective as atenolol, and equivalent to hydrochlorothiazide, either with or without amiloride, in terms of antihypertensive activity. Comparative studies also demonstrated that once daily administration with an extended-release formulation provides equivalent antihypertensive efficacy to the same amount of drug administered twice daily as the standard tablets. As a second- or third-line treatment for patients with moderate to severe hypertension refractory to standard drug combinations, felodipine produced considerable reductions in blood pressure when added to beta-blockers and diuretics, either alone or in combination, in studies lasting up to 48 weeks. In comparative studies of multiple-drug treatments felodipine was found to have superior efficacy to hydralazine and prazosin, and was at least as effective as nifedipine, minoxidil and propranolol, when used with diuretics and/or beta-blockers. As an alternative to hydrochlorothiazide, in combination with beta-blockers, felodipine consistently controlled blood pressure in a greater percentage of patients and usually provided greater decreases in blood pressure. The main side effects with felodipine are ankle oedema, headache and flushing. Although the overall incidence of effects is quite high, they are usually mild in nature. Nevertheless, withdrawal due to side effects has been necessary in about 7% of patients overall. Thus, the efficacy of felodipine has been demonstrated in mild, moderate and severe hypertension. At the present time it seems particularly suitable as a second- or third-line treatment in refractory hypertension, but it also can be used as monotherapy for mild to moderate disease.