Tezosentan (an intravenous endothelin receptor A/B antagonist) reduces peripheral resistance and increases cardiac power therefore preventing a steep decrease in blood pressure in patients with congestive heart failure.

OBJECTIVE: This study investigated the effect of tezosentan (an intravenous endothelin-1 receptor antagonist) on vascular resistance and cardiac function and determined the dose response in patients with stable congestive heart failure (CHF) due to left ventricular systolic dysfunction. METHODS: In a double-blind fashion, tezosentan or placebo were administered in ascending doses (5, 20, 50, 100 mg h(-1)) to 38 CHF (NYHA class III) patients with ejection fraction or=15 mmHg. Systemic vascular resistance index (SVRi) was estimated as mean arterial blood pressure [(MAP-right atrial pressure)/cardiac index (CI)]. Cardiac function was assessed as cardiac power index (Cpi), calculated as pressure x flow (MAP x CI), where MAP represents pressure and CI represents cardiovascular flow. RESULTS AND DISCUSSION: Compared to the placebo, tezosentan induced a dose-dependent decrease in SVRi (-32%), an increase in Cpi (+20%) and a small decrease in MAP (-9%). By contrast, patients treated with nitrate vasodilators or nesiritide (a natriuretic peptide) showed a decrease in SVRi not accompanied by a significant increase in Cpi leading to a steep decrease in MAP. CONCLUSIONS: The use of Cpi in the assessment of the hemodynamic effects of tezosentan, provides a useful alternative characterization of the complex influences of vasodilators on cardiac function in patients with CHF.

A pilot safety trial of prolonged (48 h) infusion of the dual endothelin-receptor antagonist tezosentan in patients with advanced heart failure.

STUDY OBJECTIVES: Tezosentan, an IV dual endothelin-receptor antagonist, has demonstrated beneficial hemodynamic effects in patients with advanced heart failure. In addition, no notable differences in safety and tolerability variables were detected between tezosentan-treated and placebo-treated patients when infused over 4 to 6 h. The present study was conducted primarily to assess the safety and tolerability of tezosentan when administered over a prolonged, 48-h treatment period, and secondarily to investigate hemodynamic response. DESIGN: This randomized, double-blind, active-controlled study of continual IV administration of two dosages of tezosentan (20 mg/h and 50 mg/h; n = 6 each) or dobutamine (5 microg/kg/min; n = 2) over 48 h in patients with advanced heart failure was conducted to assess tolerability, safety, and hemodynamic variables (Doppler echocardiography). RESULTS: During tezosentan infusion, no episodes of hypotension requiring withdrawal of therapy occurred, and hemodynamic rebound was not observed after abrupt cessation of the infusion. There were no reports of worsening heart failure in tezosentan-treated patients up to 28 days following the infusion. The most common side effect during the infusion was headache (9 of 12 tezosentan-treated patients and both dobutamine-treated patients). Echocardiographic Doppler measurements suggested improvements in cardiac index, pulmonary capillary wedge pressure, and relaxation properties as well as in diastolic and systolic function in all treatment groups. CONCLUSIONS: Prolonged, 48-h IV dual endothelin-receptor antagonism with tezosentan was well tolerated with no new safety concerns emerging. These data further support the potential role of tezosentan in the treatment of patients with acute heart failure.

The dual endothelin receptor antagonist tezosentan acutely improves hemodynamic parameters in patients with advanced heart failure.

BACKGROUND: Endothelin-1, a potent vasoconstrictor, is elevated in congestive heart failure and is postulated to play a major role in the pathogenesis of the disease. Endothelin receptor antagonism may be a specific therapeutic approach. This study was designed to determine the effective dosage range, hemodynamic effects, and tolerability of tezosentan, an intravenous dual endothelin receptor antagonist, in patients with advanced heart failure. METHODS: This randomized, double-blind, placebo-controlled multicenter trial enrolled 38 patients with symptomatic stable heart failure (New York Heart Association class III, left ventricular ejection fraction <35%) undergoing right heart catheterization. Patients were equally randomized to a 4-hour intravenous infusion of placebo or tezosentan in ascending doses (5, 20, 50, and 100 mg over 1 hour each). Angiotensin-converting enzyme inhibitors and diuretics were withheld 24hours before the study. Hemodynamics were measured during and for 4 hours after the infusion. RESULTS: Compared with placebo, tezosentan treatment produced a significant increase in cardiac index (treatment difference 0.59 L/min/m(2), P =.0001) and decreases in pulmonary and systemic vascular resistances (P

Hemodynamic effects of tezosentan, an intravenous dual endothelin receptor antagonist, in patients with class III to IV congestive heart failure.

BACKGROUND: Endothelin-1, a powerful mediator of vasoconstriction, is increased in patients with congestive heart failure and appears to be a prognostic marker that strongly is correlated with the severity of disease. However, little is known about the potential immediate beneficial effects of acute blockade of the endothelin system in patients with symptomatic left ventricular dysfunction. We assessed the hemodynamic effects and safety of tezosentan, an intravenous dual endothelin receptor antagonist, in patients with moderate to severe heart failure. METHODS AND RESULTS: This randomized placebo-controlled study evaluated the hemodynamic effects of 6-hour infusions of tezosentan at 5, 20, 50, and 100 mg/h compared with placebo in 61 patients with New York Heart Association class III to IV heart failure. Plasma endothelin-1 and tezosentan concentrations were also determined. Treatment with tezosentan caused a dose-dependent increase in cardiac index ranging from 24.4% to 49.9% versus 3.0% with placebo. Tezosentan also dose-dependently reduced pulmonary capillary wedge pressure and pulmonary and systemic vascular resistances, with no change in heart rate. No episodes of ventricular tachycardia or hypotension requiring drug termination were observed during tezosentan infusion. Tezosentan administration resulted in dose-related increased plasma endothelin-1 concentrations. CONCLUSIONS: The present study demonstrated that tezosentan can be safely administered to patients with moderate to severe heart failure and that by virtue of its ability to antagonize the effects of endothelin-1, it induced vasodilatory responses leading to a significant improvement in cardiac index. Further studies are under way to determine the clinical effects of tezosentan in the setting of acute heart failure.

The effect of mibefradil on ischemic episodes with and without increase in heart rate.

Myocardial ischemia during daily life can be induced by increased demand and by increased coronary tone. The purpose of this study was to assess the mechanism of action of mibefradil, a new T-channel calcium blocker that is a vasodilator with negative chronotropic properties. Included in this study were 114 patients with chronic stable angina pectoris and ischemic episodes during baseline 48-hour ambulatory ECG monitoring (AEM). After a placebo run-in period patients received 50 mg, 100 mg, or 150 mg of mibefradil per day and repeat 48 hours AEM was performed. Ischemic episodes were divided into 2 categories: Type I is those in which an increase in heart rate > 10% preceded the development of 1 mm ST depression; Type II is those with < or = 10% increase in heart rate. Of the 625 ischemic episodes recorded at baseline, 83% were Type I and 17% were Type II. At 50 mg mibefradil dose, there was a significant decrease in the number of Type I ischemic episodes but not of Type II. At doses of 100 mg and 150 mg/day, there was a significant decrease in frequency of both types of ischemic episodes. At a low dose of 50 mg/day, mibefradil reduces ischemia predominantly by preventing an increase in heart rate, while at higher doses of 100 mg and 150 mg/day, it also acted as a vasodilator suppressing episodes associated with increased coronary tone.

The efficacy and safety of mibefradil in subgroups of patients with chronic stable angina pectoris.

The pool of controlled clinical studies on mibefradil, a new selective T-type calcium channel blocker, for the treatment of chronic stable angina pectoris was analysed to determine the effects in subgroups of patients defined by age, gender, body weight and common co-existing conditions. Total exercise tolerance test duration increased similarity in all subgroups, both at 50 mg (range 8.9-17.3%; n = 383) and 100 mg mibefradil (range 23.6-30.8%; n = 235). The increases in time to onset of angina and 1 mm ST-segment depression were similarly comparable. Safety and tolerability was similar to placebo for subgroups at 50 mg, but the incidence of adverse events was slightly higher in females, older, and lower weight patients at the 100 mg dose, particularly in reported leg oedema (7.9% in females vs 1.0% in males and 5.1% in older vs 0% in younger patients). Mibefradil proved a safe, well tolerated, and effective antianginal agent that can be used regardless of demographic factors or of frequently coexisting clinical conditions.

Anti-anginal and anti-ischemic effects of mibefradil, a new T-type calcium channel antagonist.

Mibefradil is the first of a new class of calcium antagonists (CAs), the tetralol derivatives, that selectively blocks the T-type calcium channel. The anti-anginal and anti-ischemic efficacy of mibefradil in patients with chronic stable angina pectoris was established in five placebo-controlled trials (2 monotherapy trials, 3 trials with background beta-blocker or long-acting nitrate therapy). At the recommended doses of 50 and 100 mg, mibefradil treatment was associated with a significant dose-related increase in exercise test variables regardless of demographic subpopulation or background therapy. Significant reductions in weekly anginal attacks, silent ischemic parameters, heart rate (HR) and rate-pressure product were also observed. Two active-controlled trials compared mibefradil 100 mg with amlodipine 10 mg or diltiazem SR 120 mg b.i.d., respectively. Patients receiving mibefradil showed significantly larger improvements than did those treated with amlodipine and similar improvements as those treated with diltiazem SR in all variables measured. In both studies, treatment with mibefradil was associated with a greater decrease in HR and rate-pressure product. Mibefradil was found to be well tolerated and safe; this held true for patients on chronic anti-anginal background therapy. The overall incidences of adverse events and premature withdrawals were only slightly higher than those of placebo-treated patients. Asymptomatic sinus bradycardia and first-degree atrioventricular block were the most frequently occurring mibefradil dose-related ECG changes. Mibefradil was better tolerated than amlodipine (mainly with regard to leg edema) and similarly well tolerated as diltiazem CD.

A comparison of the safety and efficacy of mibefradil and nifedipine SR in patients with renal disease and hypertension.

The antihypertensive efficacy and safety of mibefradil and nifedipine SR were compared in 143 patients with chronic renal failure and mild-to-moderate hypertension in a multicenter, double-blind, randomized, parallel-design study. At treatment week 12, a significantly greater decrease in sitting diastolic blood pressure (SDBP) was seen with mibefradil than with nifedipine SR (12.8 mmHg vs 8.1 mmHg, respectively; p = 0.014). A significantly greater number of mibefradil-treated patients achieved normalization of SDBP by week 12 (62% vs 37%; p < 0.01). The changes in renal function parameters and the incidence of adverse events were similar in both groups. In this population, 12 weeks of treatment with mibefradil were more effective than nifedipine SR for lowering blood pressure and had similar effects on renal function parameters.

Adding the new calcium antagonist mibefradil to patients receiving long-term beta-blocker therapy results in improved antianginal and antiischemic efficacy.

OBJECTIVE: The objective of this study was to evaluate the efficacy, tolerability, and safety of mibefradil, a new selective T-type calcium channel blocker, in patients with chronic stable angina pectoris receiving concomitant beta-blocker therapy. DESIGN: This was a multicenter, double-blind, placebo-controlled study. METHODS: Ninety-five patients receiving a stable dose of beta-blockers, which was not changed for the purpose of the study, were administered either 50 mg mibefradil once daily for 2 weeks, then 100 mg once daily for 2 weeks, or matching placebo. Efficacy was evaluated by treadmill exercise tolerance testing 24 hours after dose and by diary registration of anginal episodes and nitroglycerin consumption. RESULTS: Two weeks of treatment with 50 mg mibefradil resulted in a significant increase in symptom-limited exercise duration and a significant delay in the onset of persistent 1 mm ST-segment depression (placebo-corrected treatment effect: 23.2 and 51.7 seconds, respectively). Treatment with the 100 mg dose for 2 additional weeks resulted in a larger improvement in treadmill exercise tolerance testing duration and onset of ischemia (placebo-corrected treatment effect: 52.7 and 75.8 seconds, respectively). In addition, a significant decrease in weekly anginal episodes was observed with the 100 mg dose of mibefradil compared with the effect in the placebo group (-53% vs - 12%, p = 0.037). CONCLUSIONS: The combined treatment of mibefradil and beta-blockers was well tolerated, and the overall incidence of adverse events was no different from that with beta-blockers alone. The results indicate that adding mibefradil to chronic beta-blocker treatment is associated with significant improvement in efficacy, which is not achieved at the expense of tolerability.

New developments in drug therapy of hypertension.

The explosion of new knowledge about the complex mechanisms mediating high blood pressure is providing new targets for drug therapy of hypertension and other cardiovascular disorders. This article reviews the current status of several new approaches in the management of hypertension, including vasopressin antagonists, natriuretic peptide clearance inhibitors, endothelin antagonists, renin inhibitors, angiotensin receptor antagonists, and selective T-type calcium ion channel antagonists.

Efficacy of mibefradil compared with amlodipine in suppressing exercise-induced and daily silent ischemia: results of a multicenter, placebo-controlled trial.

BACKGROUND: Mibefradil is a new benzimidazolyl-substituted tetraline-derivative calcium antagonist. Its vasodilatory activity combined with an ability to lower heart rate without negative inotropic effects as well as its long duration of action make it a promising anti-ischemic agent. METHODS AND RESULTS: Three hundred nine patients with coronary artery disease, stable angina pectoris, and positive exercise tests were randomized to receive mibefradil (50, 100, or 150 mg), amlodipine (10 mg), or placebo. The anti-ischemic effects of mibefradil on exercise test and silent ischemia parameters were assessed. At doses of 100 and 150 mg, mibefradil increased exercise duration (by 55.5 and 51.0 seconds, respectively; P<.001 for both), increased time to onset of angina (by 98.3 and 82.7 seconds, respectively; P<.001), and increased time to 1-mm ST depression (by 81.7 and 94.3 seconds, respectively; P<.001). By comparison, a 10 mg/d dose of amlodipine significantly improved only time to onset of angina (treatment effect: 38.5 seconds, P=.036). Mibefradil 100 mg and 150 mg decreased the number of episodes of silent ischemia (treatment effects: -3.1 and -3.6, respectively; P<.001) and the duration of silent ischemia (treatment effects: -9.2 minutes, P=.048, and -14.6 minutes, P=.002, respectively). The decrease in the number of episodes of silent ischemia was also statistically significant in the group receiving 10 mg of amlodipine (-1.5; P=.036). CONCLUSIONS: Once-daily doses of 100 and 150 mg mibefradil were effective in improving exercise tolerance and reducing ischemic episodes during ambulatory monitoring in patients with coronary artery disease.

Antihypertensive effects of mibefradil in the treatment of mild-to-moderate systemic hypertension.

This report summarizes the results of 4 double-blind, placebo-controlled studies designed to determine the efficacy, tolerability, and dose-response characteristics of the novel T-channel-selective calcium antagonist, mibefradil, in the treatment of mild-to-moderate essential hypertension. Two of these studies were conducted in the general population of essential hypertensives, 1 in elderly patients, and 1 in patients on chronic hydrochlorothiazide treatment. A total of 1,116 patients were randomized to receive 1 of 7 doses of mibefradil (6.25-200 mg; n = 927), or placebo (n = 189). Each study demonstrated a significant linear dose response in the reduction of sitting diastolic (SDBP) and sitting systolic (SSBP) blood pressure. In all 4 trials, SDBP was significantly reduced with the recommended doses of 50 and 100 mg mibefradil (placebo-corrected treatment effects of -4.1 to -6.8 mm Hg and -8.8 to -11.1 mm Hg, respectively, for the 50- and 100-mg doses). A similar reduction in SSBP occurred in 3 of 4 studies at the 50-mg dose (-7.5 to -10.7 mm Hg) and in 4 of 4 studies at the 100-mg dose (-6.8 to -16.7 mm Hg). Lower doses did not reduce blood pressure significantly; doses > 100 mg had little additional effect and an increased incidence of adverse events. Overall, response and normalization rates were dose related and averaged 61% and 51%, respectively, for the 50-mg dose and 78% and 65%, respectively, for the 100-mg dose. The onset of the antihypertensive effect was gradual, with no first-dose effect; near maximal response was reached within 1-2 weeks. Trough/peak ratios ranged from 77-86% with the 50-mg dose and from 77-108% with the 100-mg dose, indicating a sustained effect over a 24-hour period. A slight decrease in heart rate was observed, ranging from -2.2 to -5.5 beats/min at the 50-mg dose and from -4.0 to -8.8 beats/min at the 100-mg dose. The efficacy and safety results were similar across all populations studied, including the elderly and hydrochlorothiazide-treated patients, indicating that no dose adjustment is needed for these populations. Thus, the results of these 4 placebo-controlled trials confirm that when taken at the recommended doses of 50 and 100 mg once daily, mibefradil is an effective, safe, and well-tolerated therapy for the treatment of mild-to-moderate hypertension.

Antianginal and anti-ischemic effects of mibefradil in the treatment of patients with chronic stable angina pectoris.

Five placebo-controlled, double-blind, multicenter, parallel-design studies were performed to evaluate the antianginal and anti-ischemic characteristics of the novel T-channel-selective calcium antagonist, mibefradil, in the treatment of patients with chronic stable angina pectoris. Of the 5 studies, 2 were monotherapy dose-finding trials and 3 were conducted in patients receiving background antianginal therapy: either beta blockers (2 studies) or long-acting nitrates (1 study). A total of 865 patients were randomized to 1 of 4 mibefradil dose groups (25, 50, 100, and 150 mg; n = 565) and placebo (n = 300). The antianginal and anti-ischemic effects of mibefradil were assessed across all 5 studies by evaluating exercise tolerance test variables, weekly number of anginal attacks and short-acting nitroglycerin consumption, and in both dose-finding studies, the number and total duration of silent ischemic episodes (48-hour Holter monitoring). A statistically significant increase in exercise duration was achieved in 3 of 5 studies with the 50-mg dose of mibefradil and in 3 of 3 studies with the 100-mg dose of the compound over the effects observed in the placebo groups. A significant delay in time to onset of ischemia during exercise was induced in all studies with the 50- and 100-mg doses of mibefradil. The 25-mg dose of mibefradil was not significantly better than placebo, and the effects of the 150-mg dose of the compound were similar to those observed with the 100-mg dose. Across all studies, a dose-related decrease was observed in the number of weekly anginal attacks and in weekly nitroglycerin consumption. Similarly, a significant dose-related decrease in the number and duration of silent ischemic episodes was observed during Holter monitoring for 48 hours in the 2 dose-finding studies. The antianginal and anti-ischemic effects were associated with a dose-related decrease in heart rate and double product both at rest and at exercise termination. Treatment with the 50- and 100-mg doses of mibefradil was found to be well tolerated and safe compared with placebo, a finding that held true for patients on chronic beta-blocker or long-acting nitrate therapy. Taken together, these studies indicate that mibefradil is an effective and well-tolerated once-daily treatment for chronic stable angina pectoris at doses of 50 and 100 mg, which are the lowest and highest effective doses of the compound, respectively.

Mibefradil in the treatment of systemic hypertension: comparative studies with other calcium antagonists.

This paper summarizes the results of 4 double-blind studies of antihypertensive therapy in which mibefradil was compared with other commonly used calcium antagonists (diltiazem CD, amlodipine, nifedipine SR, and nifedipine GITS) at the recommended dose range. A total of 640 patients were included, with 361 randomized to mibefradil, 98 to diltiazem CD, 119 to amlodipine, 71 to nifedipine SR, and 36 to nifedipine GITS. Trials included an active treatment phase of 6 or 12 weeks in duration. Compared with diltiazem CD or nifedipine SR, mibefradil demonstrated statistically significant greater efficacy. Decreases in sitting diastolic blood pressure (SDBP) after treatment with mibefradil 100 mg once daily were 14.0 +/- 7.8 mm Hg compared with 9.5 +/- 7.5 mm Hg with diltiazem CD 360 mg once daily (p = 0.001), and 12.8 +/- 8.4 mm Hg compared with 8.1 +/- 19.2 mm Hg with nifedipine SR 40 mg twice daily (p = 0.014). Patients on mibefradil also had higher normalization (SDBP reduced to < or = 90 mm Hg) and response (SDBP reduction > or = 10 mm Hg or normalization) rates than did those on diltiazem CD or nifedipine SR. The overall incidence of adverse events was similar among these 3 compounds, but the number of premature withdrawals due to adverse events was greater with both comparators than with mibefradil. Treatment with 100 mg mibefradil or 10 mg amlodipine once daily resulted in statistically significant decreases from baseline in SDBP of 11.5 +/- 8.2 mm Hg and 13.2 +/- 7.9 mm Hg, respectively, which were statistically equivalent. However, patients treated with amlodipine had a considerably greater incidence of leg edema than did those treated with mibefradil (33.6% vs 4.2%, respectively). Similarly, 100 mg mibefradil was equivalent in efficacy to 60 mg nifedipine GITS once daily, but patients on mibefradil experienced fewer vasodilatory related adverse events. In summary, mibefradil demonstrated superior efficacy to diltiazem CD and nifedipine SR and equivalent efficacy to amlodipine and nifedipine GITS in the treatment of hypertension.

Mibefradil in the treatment of chronic stable angina pectoris: comparative studies with other calcium antagonists.

The ability of mibefradil, a new T-channel-selective calcium antagonist, to improve exercise tolerance and silent ischemic parameters in patients with chronic stable angina was compared in 3 separate trials with 2 other commonly used calcium antagonists: diltiazem SR (120 mg/twice daily) and amlodipine (10 mg/day). Compared with amlodipine, mibefradil 100 mg given once daily over a 3-week period resulted in a statistically significantly larger increase from baseline in total exercise tolerance test (ETT) duration (treatment difference of 40.9 sec, p = 0.04), time to onset of angina (treatment difference 61.2 sec, p < 0.001), and time to onset of ischemia (treatment difference of 54.4 sec, p = 0.004). The decrease in weekly anginal episodes was 58% with mibefradil versus 19% with amlodipine, and the reduction in nitroglycerin consumption was 58% with mibefradil versus a 10% increase with amlodipine. The decrease in the number of silent ischemic episodes detected by a 48-hour Holter recording was significantly larger (p = 0.03) with mibefradil 100 mg (88%) compared with amlodipine 10 mg (38%). Similarly, a larger decrease in the duration of silent ischemia was observed with mibefradil (69%) compared with that seen with amlodipine (38%). The preliminary results of a second trial comparing mibefradil with amlodipine were consistent with the first demonstrating that the improvement for all 3 ETT parameters was larger for mibefradil (ETT duration: 55.2 sec; delay in onset angina: 74.2 sec; time to onset of ischemia: 63.6 sec), but in this trial the treatment differences did not reach statistical significance. In the trial comparing mibefradil (100 mg once daily) with diltiazem SR (120 mg twice daily), both compounds had equivalent effects on all ETT parameters tested. Mibefradil produced a 21% increase in exercise duration compared with a 20% increase with diltiazem. Although mibefradil yielded larger increases in the time to onset of angina and the time to onset of 1-mm ST-segment depression (42% and 38%, respectively) than did diltiazem (34% and 25%, respectively), the treatment differences did not reach statistical significance. Both mibefradil and diltiazem SR were associated with at least a 70% reduction from baseline in anginal frequency and nitroglycerin consumption. Mibefradil-treated patients showed greater decreases in heart rate and the rate-pressure product at each stage of the ETT than patients treated with amlodipine or diltiazem SR. All 3 drugs were well tolerated. However, compared with mibefradil, amlodipine and diltiazem SR produced a higher incidence of leg edema. In conclusion, the effectiveness of mibefradil in improving all 3 ETT parameters was greater than that of amlodipine and equivalent to that of diltiazem SR. Moreover, mibefradil provided greater reductions in the heart rate and cardiac workload than did the other 2 drugs.

Safety of mibefradil, a new once-a-day, selective T-type calcium channel antagonist.

The safety and tolerability of mibefradil, a selective T-type calcium channel antagonist, were evaluated in 3,430 patients with essential hypertension and chronic stable angina pectoris treated in 15 double-blind placebo and active-controlled clinical trials and 2 open-label, long-term safety studies. Of these patients, 2,636 were treated with the recommended doses of mibefradil (50 and 100 mg) and form the basis of this report. With the 50-mg dose of mibefradil, the incidence of each adverse event was similar to, or lower than, that observed in the placebo-treated patients. Treatment with the 100-mg dose was associated with a slightly higher incidence compared to placebo of dizziness (2.1% vs 1.8%), leg edema (3.5% vs 1.4%), fatigue (2.1% vs 1.4%), and lightheadedness (2.1% vs 0.4%). The incidence of headache (4.6%) and angina pectoris (1.1%) was more frequent in patients treated with placebo. In active-controlled trials, a lower incidence of pedal edema (5.1%) was observed with mibefradil compared to amlodipine (25.7%), diltiazem SR/CD (9.4%), or nifedipine SR/GITS (17.4%). Overall, mibefradil was better tolerated than amlodipine and nifedipine SR/GITS and was as well tolerated as diltiazem SR/CD. Rates of premature discontinuation due to clinically adverse experiences with the 50- and 100-mg doses were 2.5% and 3.5%, respectively, compared with placebo (3.5%). No consistent pattern of laboratory adverse experiences were observed for mibefradil. Sinus bradycardia (heart rate <45 beats/minute) and first-degree atrioventricular block were the only relevant treatment-emergent electrocardiographic changes that occurred more frequently with mibefradil than with placebo. No evidence of first-dose effects was observed in mibefradil-treated patients, and withdrawal effects were not observed in clinical trials. There were no clinically important differences in safety profiles in the demographic subgroups for age, gender, or race. The results of this comprehensive safety analysis indicate that treatment with the recommended doses of mibefradil is well tolerated and safe.

Long-term antianginal and antiischemic effects of mibefradil, the novel T-type calcium channel blocker: a multicenter, double-blind, placebo-controlled, randomized comparison with sustained-release diltiazem.

This study compared the efficacy, safety, and tolerability of mibefradil to sustained-release diltiazem in patients with chronic stable angina pectoris. At week 12, statistically equivalent mean increases in exercise tolerance test (ETT) duration of > 1 minute were observed in both groups. Similar improvements in time to onset of angina and time to persistent 1 mm ST-segment depression were also observed with both drugs. Large reductions in heart rate, blood pressure, and rate-pressure product were observed at each stage of the ETT among patients treated with mibefradil. Each drug was associated with at least a 70% reduction from baseline in anginal frequency and nitroglycerin consumption. Patients maintained on mibefradil during the withdrawal period had significant increases in all three ETT variables at week 16 compared with placebo. The effectiveness of mibefradil is comparable with sustained-release diltiazem in treating chronic stable angina pectoris, although mibefradil provides greater reductions in heart rate and cardiac workload.

Mibefradil, a novel calcium antagonist, in elderly patients with hypertension: favorable hemodynamics and pharmacokinetics.

A multicenter, double-blind, placebo-controlled study of 310 elderly patients with mild-to-moderate essential hypertension was conducted in 20 sites throughout Europe, Brazil, and Israel to assess the antihypertensive efficacy, tolerability, safety, and dose-response characteristics of the novel calcium antagonist mibefradil in the elderly. Patients were randomly assigned to receive once-daily doses of 6.25, 12.5, 25, 50, or 100 mg of mibefradil or placebo for 4 weeks. Statistically significant and clinically relevant reductions in sitting diastolic blood pressure (SDBP) and sitting systolic blood pressure (SSBP) were observed with the 50 and 100 mg doses. Therapeutic responses reached 88.5% for SDBP and 76.5% for SSBP in the 100 mg group. Trough/peak ratios were > 75% in SDBP and SSBP with the 50 mg and 100 mg doses. At doses of 50 to 100 mg once daily, mibefradil was well tolerated and effective with a high antihypertensive response rate and consistent 24-hour blood pressure control in elderly patients.

Dose-response characteristics of mibefradil, a novel calcium antagonist, in the treatment of essential hypertension.

The aim of this study was to determine the dose-response characteristics of the calcium antagonist, mibefradil, and to evaluate its antihypertensive efficacy and safety in varying doses in patients with mild-to-moderate hypertension. Three hundred and three eligible patients were randomized to receive once-daily 6.25-, 12.5-, 25-, 50-, 100-, 150-, or 200-mg mibefradil doses or placebo for 4 weeks. Repeated blood pressure measurements and electrocardiographic recordings were obtained for the 24 h following the last dose of the placebo run-in period and for the first and last doses of randomized treatment. A statistically significant (P < .001 versus placebo) and clinically relevant drop in sitting diastolic blood pressure (SDBP) both at trough and at peak was observed in the 50-, 100-, 150-, and 200-mg mibefradil dose groups (trough placebo-corrected reductions: -4.9, -9.1, -9.9, and -11.9 mm Hg, respectively), with a significant dose-response relationship (P < .001) and high response rates. Trough/peak ratios for the placebo-corrected change from baseline to week 4 in SDBP were >85% for the 50- and 100-mg doses and 68% and 69% for the 150- and 200-mg doses, respectively. The full antihypertensive effect of mibefradil was achieved within 1 week of treatment. Reductions in sitting systolic blood pressure (SSBP) closely paralleled those in SDBP. The antihypertensive effect of mibefradil was associated with a slight dose-dependent decrease in heart rate and increase in the pulse rate (PR) electrocardiographic interval [corrected]. The appropriate therapeutic dose range of mibefradil in the management of mild-to-moderate essential hypertension is 50 to 100 mg.

The addition of mibefradil to chronic hydrochlorothiazide therapy in hypertensive patients is associated with a significant antihypertensive effect.

OBJECTIVE: To evaluate the antihypertensive efficacy, tolerability, safety, and dose-response characteristics of the novel calcium antagonist, mibefradil, in combination with a diuretic regimen. DESIGN: A multinational, double-blind, randomised, placebo-controlled, parallel-design trial. METHODS: Three hundred and seven patients whose mild-to-moderate essential hypertension remained uncontrolled after 4 weeks of treatment with hydrochlorothiazide (HCTZ) 25 mg/day and placebo were randomised to receive combined treatment with HCTZ and once-daily doses of 12.5, 25, 50, or 100 mg of mibefradil or placebo. After 8 weeks of combined treatment, HCTZ was withdrawn and the mibefradil groups continued on their respective doses for an additional 6 weeks. RESULTS: After 8 weeks, the addition of once-daily doses of mibefradil to the initial HCTZ regimen resulted in clinically relevant, dose-related reductions in sitting diastolic blood pressure (SDBP) and sitting systolic blood pressure (SSBP) at trough, which were significantly greater in the 50 and 100 mg dose groups compared to the placebo group (P < or = 0.003). Placebo-corrected treatment effects on SDBP and SSBP at the end of the combined treatment period relative to baseline were, respectively, -4.1 and -8.0 mm Hg in the 50 mg mibefradil group and -9.5 and -8.0 mm Hg in the 100 mg mibefradil group. Therapeutic response rates to combination mibefradil and HCTZ therapy were high and dose related, reaching 82% for SDBP in the 100 mg group. CONCLUSIONS: The addition of once-daily doses of 50 or 100 mg of mibefradil to patients whose hypertension is not controlled by HCTZ alone is well tolerated and effective in improving BP control.