Antihypertensive effect of felodipine or hydralazine when added to beta-blocker therapy

Direct Vasodilators and Sympatholytic Agents

Direct vasodilators and sympatholytic agents were some of the first antihypertensive medications discovered and utilized in the past century. However, side effect profiles and the advent of newer antihypertensive drug classes have reduced the use of these agents in recent decades. Outcome data and large randomized trials supporting the efficacy of these medications are limited; however, in general the blood pressure-lowering effect of these agents has repeatedly been shown to be comparable to other more contemporary drug classes. Nevertheless, a landmark hypertension trial found a negative outcome with a doxazosin-based regimen compared to a chlorthalidone-based regimen, leading to the removal of α-1 adrenergic receptor blockers as first-line monotherapy from the hypertension guidelines. In contemporary practice, direct vasodilators and sympatholytic agents, particularly hydralazine and clonidine, are often utilized in refractory hypertension. Hydralazine and minoxidil may also be useful alternatives for patients with renal dysfunction, and both hydralazine and methyldopa are considered first line for the treatment of hypertension in pregnancy. Hydralazine has also found widespread use for the treatment of systolic heart failure in combination with isosorbide dinitrate (ISDN). The data to support use of this combination in African Americans with heart failure are particularly robust. Hydralazine with ISDN may also serve as an alternative for patients with an intolerance to angiotensin antagonists. Given these niche indications, vasodilators and sympatholytics are still useful in clinical practice; therefore, it is prudent to understand the existing data regarding efficacy and the safe use of these medications.

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.

Comparison of once daily felodipine 10 mg ER and hydrochlorothiazide 25 mg in the treatment of mild to moderate hypertension

The efficacy of extended release felodipine 10 mg (ER) o.d., a new dihydropyridine calcium antagonist, and 25 mg hydrochlorothiazide (HCTZ) o.d. have been compared in a randomized, double-blind, crossover trial in 28 mildly to moderately hypertensive subjects (supine diastolic blood pressure, BP, greater than or equal to 95 mm Hg and less than or equal to 110 mm Hg on three separate occasions). Both drugs significantly reduced systolic and diastolic BP in the sitting position felodipine from 157.1/93.8 mm Hg at baseline to 133/78.9 mm Hg 2.5 h after medication and to 138/82.7 mm Hg after 2 weeks of treatment, and HCTZ from 156/95.6 mm Hg to 147/88.4 mm Hg 2.5 h after medication and to 149/89.5 mm Hg also after 2 weeks. A decrease of the same magnitude in standing systolic and diastolic BP was observed after both treatment regimens with the exception of diastolic BP 2.5 h after dosing with HCTZ, which was not significantly lower. At all times (2.5 h and 2 weeks), the reduction in systolic and diastolic BP was greater after felodipine compared to HCTZ. Heart rate was significantly increased after felodipine in both the sitting and standing positions, and both 2.5 h following medication and after 2 weeks of treatment. The difference between the regimens was significant only 2.5 h after dosing. Overall, felodipine 10 mg ER o.d. was superior to 25 mg HCTZ o.d. in lowering BP.

Calcium antagonists: an overview

Calcium antagonists reduce the influx of calcium ions through the calcium channels. This causes a reduction in myocardial contractility or a fall in vascular resistance because of a lowering of vascular smooth muscle tone. Therefore, the net effect is a fall in blood pressure. The three major classes of calcium antagonists, the dihydropyridines, papaverine derivatives, and benzothiazepines, differ in molecular structure and their binding characteristics to the calcium channels. Furthermore, newer antagonists, particularly the dihydropyridines such as nicardipine, have a high affinity for vascular tissue and are highly selective for vascular smooth muscle. These compounds also have a favorable effect on hypertension mainly because of lowering of vascular resistance. In addition, they do not cause potentially negative metabolic effects on glucose or lipid levels and are generally well tolerated. Based on these findings, the Joint National Committee in the United States and the World Health Organization/International Society of Hypertension Committee on the Management of Mild Hypertension recommended the use of calcium antagonists as first-line treatment in hypertension.

Review of state-of-the-art beta-blocker therapy

Beta-adrenoceptor blocking drugs have been used in the treatment of hypertension for more than 2 decades. During this time they have reached the position of first-line therapy for hypertension and are recommended as such by the Joint National Committee (U.S.A.) in 1988 and by the World Health Organization/International Society of Hypertension in 1983 and 1989. This is because of the favorable relationship between the antihypertensive efficacy of these drugs and the rate and severity of their adverse effects. Of particular interest is the possibility that beta blockers may protect against coronary artery disease (CAD). With regard to secondary prevention against CAD, statistically highly significant and clinically relevant reductions of mortality and the risk of reinfarction have been shown in prospective, double-blind, placebo-controlled trials. A primary preventive effect against CAD, on the other hand, has only been shown in open trials without placebo control. However, in spite of the lack of clear proof, this effect still appears to be a logical possibility. Some new findings with beta blockers appear to be of particular interest: beta blockade may reduce myocardial necrosis in patients with marked elevations of plasma catecholamines due to traumatic head injury; a similar protective effect in other situations of severe stress, e.g., acute myocardial infarction, would be of great clinical value. Experimental studies also suggest that beta blockers may have antiatherosclerotic effect in animals fed an atherogenic diet and subjected to stress. Again, clinical confirmation of such results would be of great significance.

Aspects of quality of life on treatment with felodipine

Quality of life has been assessed in a double-blind four week study comparing felodipine 5, 10, 20 mg and placebo added to metoprolol by adding two self-administered questionnaires to the conventional procedure for the evaluation of adverse events. None of the aspects related to general well-being was affected by felodipine. The subjective symptoms reported were mostly dose-related and so here mainly observed at the highest dose. Some of them, e.g. headache, were transient. It is concluded that felodipine in combination with metoprolol CR did not negatively influence the feeling of well-being of the patients. When the drug was given in low, individually adjusted doses, the symptoms normally associated with Ca antagonists were likely to be minimised.

Felodipine extended release in mild to moderate hypertension

A multi-centre study was carried out to examine the antihypertensive effect and adverse event profile of felodipine in an extended-release (ER) formulation given once daily as monotherapy. Doses of 5 mg, 10 mg or 20 mg felodipine ER were compared with placebo in 183 patients with mild or moderate hypertension. All antihypertensive medication was discontinued on entering a 4-week placebo run-in period. If, at the end of the run-in period, supine diastolic blood pressure was in the range greater than 95 less than 120 mmHg, patients were randomly allocated to double-blind treatment with felodipine, 5 mg, 10 mg or 20 mg, or placebo, to be taken once daily for 4 weeks. Supine and standing blood pressure, heart rate and body weight were measured every 2 weeks during the trial. Assessments were made 24 hours after intake of the study drug. Adverse events were recorded at each review. Over the 4-week treatment period, a dose-related decrease in supine diastolic blood pressure was observed, this reduction occurring already during the first 2 weeks of active treatment. In the placebo group and the felodipine 5 mg, 10 mg and 20 mg groups, supine blood pressure (systolic/diastolic) decreased by 7/6 mmHg, 9/8 mmHg, 12/10 mmHg and 14/11 mmHg, respectively. Supine diastolic blood pressure reduction in the felodipine 10 mg group and both systolic and diastolic blood pressure reductions in the 20 mg group were significantly greater than with placebo. Standing diastolic blood pressure reduction was significantly greater in all three dose groups on felodipine compared with placebo.(ABSTRACT TRUNCATED AT 250 WORDS)

Felodipine in combination with a beta-adrenoceptor blocker as an effective substitute for triple therapy in severe hypertension. The Australian Felodipine Multicentre Study Group

We have studied the efficacy and tolerability of felodipine plus a beta-adrenoceptor blocker in 79 patients with essential hypertension previously treated with a combination of three or more anti-hypertensive agents, one of which was a beta-adrenoceptor blocker. After a 4-week run-in period on the same beta-blocker plus placebo (as a substitute for the other agents in the regimen), felodipine was added and its dose titrated to achieve a supine diastolic blood pressure or less than 90 mm Hg. This was followed by a 12-week maintenance phase in all patients, and 47 patients entered an optional long-term follow-up for an additional 9 months. The mean supine blood pressure was 149/88 mm Hg at entry and 174/108 mm Hg after the run-in phase. Felodipine significantly reduced the blood pressure to 142/85 mm Hg after dose titration and to 141/84 mm Hg after 12 weeks, 94% of patients achieving a supine diastolic blood pressure of 90 mm Hg or below. This reduction was maintained in the patients who were followed for 12 months. The adverse events recorded were usually mild, transient, and typical for an effective precapillary vasodilator. Nine of 74 patients (11%) were withdrawn in the first phase of the study because of adverse events and 5 of 47 patients were withdrawn during the long-term follow-up. These results show that the efficacy and tolerability of a combination of felodipine with a beta-blocker allow a simplified regimen for hypertensive patients who were previously taking three or more drugs for satisfactory blood pressure control.

The efficacy and tolerability of long-term felodipine treatment in hypertension. The Scandinavian Multicenter Group

The antihypertensive effect of felodipine and hydrochlorothiazide, both given in addition to beta-blockers, were compared in this double-blind multicenter study in 103 patients. To all patients concluding the study (n = 92), felodipine was given openly, and the antihypertensive effect and tolerability was studied for 1 year. Patients with a diastolic blood pressure greater than or equal to 100 mmHg, despite beta-blocker treatment, were randomized to treatment with felodipine 5 mg twice daily (n = 51) or hydrochlorothiazide 25 mg (n = 52) once daily for 4 weeks. The dose was then doubled in all patients for a second 4-week period. During open follow-up, all patients were given felodipine 5-15 mg (starting dose 5 mg) twice daily in addition to the beta-blocker. Hydrochlorothiazide could also be added. Reductions in systolic and diastolic blood pressure were significantly greater with felodipine than with hydrochlorothiazide at both the low and high dose levels. There were significantly more responders (diastolic blood pressure less than or equal to 90 mmHg or fall of greater than or equal to 10 mmHg) in the felodipine group. Felodipine and hydrochlorothiazide were both well tolerated. Hydrochlorothiazide treatment was accompanied by a decrease in serum potassium and an increase in serum uric acid. One year of treatment felodipine therapy resulted in a blood pressure fall from baseline of 34/23 mmHg. The most commonly reported adverse event was ankle edema. No clinically important changes in blood tests were seen during felodipine treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Felodipine in the treatment of patients with severe hypertension and impaired renal function

Twenty-three patients with severe hypertension and impaired renal function were included in an open study of the efficacy and tolerance of felodipine treatment over 6 months. All patients were previously treated with a diuretic, a beta blocker, and a vasodilator, and eight of them also received an ACE inhibitor. At the start of felodipine treatment the previously used vasodilator was withdrawn. In nine patients the concomitant antihypertensive treatment was reduced during the study. The glomerular filtration rate (GFR), as 51Cr EDTA clearance, was determined before and at the end of the study. The blood pressure (BP) and heart rate (HR) were recorded at all clinical visits in the morning 12 hours after the evening dose of felodipine and 2 hours after the morning dose. Plasma concentrations of felodipine were measured at every visit before the morning dose and 2 hours after dose. The BP was reduced after felodipine was substituted for the previously used vasodilator. A significant additional anti-hypertensive effect was recorded 2 hours after the dose and amounted to -37 +/- 22/-15 +/- 12 mmHg (p = 0.0001/p = 0.0002) at 6 months. The effect measured 12 hours after the dose was less pronounced and was -11 +/- 28/-6 +/- 10 mmHg (p = 0.15/p = 0.03). Mean GFR was unchanged during the study, 38 +/- 19 versus 38 +/- 19 ml/min (n = 16). There was a sixfold interindividual variation in the trough plasma concentrations at steady state at the same drug dosage. Higher plasma concentrations seemed to be required to achieve the same antihypertensive effects as in patients with less severe hypertension and normal renal function.(ABSTRACT TRUNCATED AT 250 WORDS)

General considerations in selecting antihypertensive agents in patients with type II diabetes mellitus and hypertension

The Working Group on Hypertension in Diabetes recommends starting pharmacologic treatment of hypertension with a small dose of a thiazide, beta-blocker, prazosin hydrochloride, angiotensin-converting enzyme inhibitor, or calcium channel blocker. Thus, these alternatives are regarded as first-line treatment in hypertensive patients with diabetes mellitus. Both thiazides and beta-blockers can cause deterioration in glycemic control and have an unfavorable influence on the lipoprotein profile. These metabolic side effects may partly counteract beneficial effects. Non-selective beta-blockers should probably be avoided in diabetic patients, since blockade of the beta-2 receptor may be associated with a compromise in peripheral blood flow and with problems associated with hypoglycemia. Cardioselective beta-blockers, which may have primary preventive effects on coronary disease, are beneficial in this patient group. In patients with non-insulin-dependent diabetes mellitus without nephropathy or overt fluid retention, diuretic therapy could be replaced by sodium restriction and/or calcium channel blocker therapy, since these agents also have a mild diuretic effect. Calcium channel blockers, angiotensin-converting enzyme inhibitors, and prazosin hydrochloride have minimal metabolic side effects, making them suitable for treatment of hypertension in this patient group.