Diltiazem as monotherapy for systemic hypertension: a multicenter, randomized, placebo-controlled trial

Clinical benefits versus shortcomings of diltiazem once-daily in the chronotherapy of cardiovascular diseases

BACKGROUND

The introduction of chronotherapy (that is improving a drugs therapeutic efficacy by paralleling the drugs plasma levels to circadian rhythms) has recently become a focus of interest.

OBJECTIVE

This article addresses the efficacy and potential shortcomings of chronotherapy, and focuses on one specific type of chronotherapy: a novel long-acting diltiazem formulation, DTZ-LA.

METHODS

We reviewed the literature to assess the clinical benefits and shortcomings associated with DTZ-LA in the management of hypertension and angina.

RESULTS/CONCLUSIONS

The clinical benefits of DTZ-LA outweigh its disadvantages when surrogate outcomes are evaluated, but it still remains to be determined whether chronotherapy benefits hard clinical outcomes. Nonetheless, chronotherapy has the potential to address the cardiovascular triggers that peak in the early morning hours when the preponderance of cardiovascular events occur, as well as providing better target organ protection compared with non-chronotherapeutic therapy.

Long-acting diltiazem HCL for the chronotherapeutic treatment of hypertension and chronic stable angina pectoris

Hypertension is associated with increased cardio- and cerebrovascular morbidity and mortality; antihypertensive drugs have been shown to reduce the risk of adverse cardio- and cerebrovascular events. These events tend to be more common during the morning hours, a time when both normo- and hypertensives show a circadian peak in blood pressure (BP). Although clinicians have a number of safe and well-tolerated antihypertensive agents in various classes and formulations at their disposal, few are designed to specifically attenuate the morning BP surge while maintaining 24-h efficacy. A novel, once-daily, long-acting formulation of diltiazem HCl (DTZ-LA) has been developed with chronodynamics in harmony with diurnal BP variation. DTZ-LA effectively reduces BP in a dose-dependent fashion over a 24-h dosing interval in patients with moderate-to-severe essential hypertension. When compared with a morning dose, the evening dose is associated with significant and clinically meaningful greater reductions in BP during the morning hours, when adverse cardiovascular events tend to cluster. Evening-dosed DTZ-LA was more effective than morning-dosed amlodipine in reducing morning diastolic BP in African-Americans. Evening-dosed DTZ-LA was also more effective than evening-dosed ramipril in reducing morning BP. Evening dosing of DTZ-LA significantly increased exercise tolerance in patients with angina pectoris over the 24-h interval. DTZ-LA is associated with adverse effects consistent with other diltiazem formulations, and overall is safe and well tolerated, even when titrated to doses of 540 mg/day.

Fulminant chemical hepatitis possibly associated with donepezil and sertraline therapy

OBJECTIVE

To describe a case of fulminant hepatitis possibly related to concomitant donepezil and seratriline therapy.

PATIENT AND SETTING

An 83-year-old woman treated in a dementia care facility and later in a tertiary medical center.

INTERVENTION AND MANAGEMENT

Discontinuation of donepezil and sertraline therapy with subsequent improvement evidenced by liver biopsy and liver function tests.

RESULTS

An older woman with Alzheimer's disease was admitted to a dementia care facility because of aggressive behavior. Treatment with sertraline was initiated in February 1998. Sertraline doses were increased gradually to 200 mg daily by May 1998, and some improvement in behavior was seen. Concomitant therapy with donepezil 5 mg qhs was initiated June 26, 1998. Ten days later, confusion and jaundice were noted. Total bilirubin was 5.6 mg/dL, GGTP was 1,208 IU/L, and alkaline phosphatase was 369 IU/L. Computed tomography revealed cholelithiasis without ductal dilation. Liver, spleen, and pancreas seemed normal. Donepezil and sertraline were discontinued. The patient was admitted to our institution and treated for dehydration. A liver biopsy revealed scattered portal eosinophils and prominent cholestasis consistent with acute chemical hepatitis. The GGTP and total bilirubin of this patient peaked at 2,235 IU/L and 22.6 mg/dL, respectively. The patient improved, and her liver function tests normalized over the next 2 months.

Anomalies in the dosing of diltiazem

From early research, investigators understood that the dose of diltiazem required for the treatment of hypertension (commonly 360 mg/day) was greater than that required for the treatment of angina (commonly 240 mg/day). Nonetheless, studies of recent prescribing practices show that the 240 and 180 mg capsule strengths constitute more than 70% of the diltiazem prescriptions for hypertension. Physicians became accustomed to the lower antianginal doses of diltiazem for 7 years before a hypertension indication was approved. Subsequently, these dosing levels were reinforced by the production of once-a-day formulations with highest capsule strengths of 240 mg and 300 mg. These strengths were dictated by the sheer bulk of the formulations, which limited how much diltiazem could be inserted into the #00 capsule, the largest capsule that can be comfortably administered. An examination of the combined data from the six randomized, blinded, and placebo-controlled trials submitted to the FDA for the original new drug applications of the three formulations of diltiazem available in the United States shows a clear linear dose-response relationship between diltiazem dose and blood pressure lowering through the 480-540 mg/day range. It also demonstrates that the 90-120 mg/day range is the "no-effect dose." These conclusions are supported by a MEDLINE review of all other studies of multilevel dosing of higher dose levels of diltiazem. The data support the conclusion that diltiazem is generally underdosed, but when properly dosed may be the single most potent antihypertensive overall.

A placebo-controlled comparison of diltiazem and amlodipine monotherapy in essential hypertension using 24-h ambulatory monitoring

Thirty patients (17 females, median age 55 years) with mild/moderate hypertension (sitting diastolic blood pressure 95-110 mmHg over 2 consecutive weeks) participated in a study of the efficacy and tolerability of once-daily diltiazem "controlled delivery" 180 mg-360 mg and amlodipine 5-10 mg compared with placebo (using clinic and 24-h ambulatory blood pressure measurement (Accutraker II). The study was conducted in a general practice setting using a randomized double-blind crossover design with Latin square allocation of treatment order within subjects. During each phase, doses were titrated to achieve a predose clinic sitting diastolic blood pressure of 90 mmHg. Three patients withdrew while taking amlodipine and 3 while taking placebo. The numbers of patients receiving the higher dose in each phase were as follows: placebo 22, diltiazem 12 and amlodipine 19. End-of-phase mean clinic sitting blood pressures were as follows: placebo 152/100, diltiazem 146/95 and amlodipine 140/93. End-of-phase mean 24-h ambulatory blood pressures were as follows: placebo 151/93, diltiazem 143/86 and amlodipine 137/84. Both clinic and ambulatory blood pressures were therefore significantly reduced (p < 0.01) in both active phases compared with placebo, and systolic blood pressure was also significantly lower with amlodipine compared with diltiazem. Heart rate was increased with amlodipine. Both drugs were well tolerated, and adverse events were predictable for each agent, with amlodipine causing more vasodilator side effects. Thus both amlodipine and diltiazem once-daily are effective in reducing blood pressure. While amlodipine is more potent than diltiazem in reducing systolic blood pressure, it causes more vasodilator side effects.

Optimization of antihypertensive therapy with a novel, extended-release formulation of diltiazem: results of a practice-based clinical study

Although the effectiveness of diltiazem for the treatment of patients with hypertension has been well demonstrated in numerous placebo-controlled and comparative clinical trials, most physicians have had some concern about its efficacy and have used it predominantly in patients with mild hypertension. Few large-scale studies have evaluated the efficacy and safety of higher dosages of diltiazem for the treatment of patients with hypertension, and few have evaluated the use of diltiazem in patients with more severe hypertension. Tiazac (Forest Pharmaceuticals, Inc., St. Louis, Missouri), a new, extended-release formulation of diltiazem, provides 24-hour blood pressure control with a single daily dose of up to 360 mg. The Study of Titration and Response to Tiazac (START) is an ongoing practice-based, open-label, multicenter study designed to evaluate the efficacy and safety profiles of Tiazac at greater-than-traditional doses in hypertensive patients and to assess the ability of Tiazac to decrease the rate-pressure product, a surrogate marker for cardiac workload. Patients were eligible for study entry whether their hypertension was newly diagnosed or previously treated with a different formulation of diltiazem or any other antihypertensive agent. Normotensive (sitting diastolic blood pressure [SDBP] < 90 mm Hg) subjects and those with mild (SDBP 90 to 99 mm Hg), moderate (SDBP 100 to 109 mm Hg), severe (SDBP 110 to 119 mm Hg), and very severe (SDBP > or = 120 mm Hg) hypertension were assessed at baseline (visit 1), visit 2 (10 to 14 days after visit 1), and visit 3 (25 to 28 days after visit 1). A total of 3082 patients were enrolled, and data from 2802 assessable patients (i.e., those who completed visits 1, 2, and 3) were analyzed. No subjects were lost to follow-up as a result of adverse effects. All subjects received a starting dose of Tiazac 180 mg or 240 mg once daily, and doses were titrated upward to 360 mg once daily as clinically indicated. Blood pressure reduction matched the severity of hypertension in all patients. Subjects who were switched from another diltiazem formulation demonstrated further decreases in SDBP. Antihypertensive monotherapy with Tiazac was well tolerated. This interim START report demonstrates that a daily dose of up to 360 mg of diltiazem is optimal in terms of both control of hypertension and patient compliance. It also provides the practice-based physician with useful clinical information on dose titration and response to a new formulation of an approved drug and supports the efficacy and safety profiles of diltiazem documented in previous well-controlled clinical trials.

Effect of morning versus evening dosing of diltiazem on myocardial ischemia detected by ambulatory electrocardiographic monitoring in chronic stable angina pectoris. Dilacor XR Ambulatory Ischemia Study Group

Myocardial ischemia occurs frequently during daily life and has a circadian pattern similar to that reported for myocardial infarction and sudden death. Because of the increased risk of myocardial ischemia in the morning hours, it has been suggested that the administration of anti-ischemic medication before bedtime may be more effective than the traditional morning dosing. This randomized, double-blind, placebo-controlled, crossover study evaluated the effects of 480-mg/day diltiazem (given either in the A.M. or the P.M.) on myocardial ischemia using ambulatory electrocardiographic monitoring in 68 patients with chronic stable angina and > or = 2 minutes of ischemia per 48 hours. During treatment with diltiazem, the duration and number of myocardial ischemic episodes were reduced by 45% (94 to 52 minutes, p <0.004) and by 40% (4.5 to 2.7 episodes, p <0.003), respectively. The duration and number of myocardial ischemic episodes during daytime (6 A.M. to 6 P.M.) hours were also reduced by 52% (74 to 36 minutes, p <0.002) and by 48% (3.1 to 1.6 episodes, p <0.001), respectively. There was no significant difference between A.M. and P.M. dosing. Morning ischemia (6 A.M. to noon), considered separately from daytime ischemia, was also significantly reduced by both A.M. and P.M. dosing regimens, with no difference between the regimens. The results of this study showed that both A.M. and P.M. dosing of long-acting diltiazem were equally effective in suppressing episodes of ambulatory myocardial ischemia at all times.

Hypertension in Elderly Persons

OBJECTIVE

To provide an overview of the prevalence of hypertension in the elderly population and discuss the advantages and disadvantages of various classes of antihypertensive drugs.

METHODS

We review the published clinical trials on treatment of elderly patients with hypertension and describe adverse reactions that are frequently associated with antihypertensive therapy.

RESULTS

On the basis of the standard for control of hypertension established by the National Health and Nutrition Examination Survey for 1988-1991 (140/90 mm Hg), almost 75% of all African-Americans and 50% of all whites 60 to 74 years of age have hypertension. If modifications in lifestyle (such as weight reduction and increase in exercise) do not normalize blood pressure levels, drug therapy is warranted. Meta-analyses of major trials of treatment of hypertension have revealed significant reductions in cardiovascular-related mortality and stroke, and available data indicate that prudent use of antihypertensive agents is associated with an acceptable degree of toxicity. Low-dose thiazide diuretics and b-blockers remain the agents of choice.

CONCLUSION

Several trials have substantiated the effectiveness of treatment of hypertension in elderly subjects. Drug therapy should be initiated at low doses, and careful follow-up should monitor for adverse effects.

Administration-time-dependent effects of diltiazem on the 24-hour blood pressure profile of essential hypertension patients

The aim of this study was to identify differences in the patterns of efficacy and duration of effect by diltiazem given in different dosage forms and schedules. Blood pressure (BP) and heart rate (HR) were monitored before and after treatment by ambulatory blood pressure monitoring for 48 h every 30 min. Patients were divided for treatment assignment into 4 groups -nocturnal BP dippers and nondippers. In dipper hypertension, diltiazem-retard at 08:00 (n = 7) had the most marked antihypertensive effects during nighttime rest (SBP; 136 +/- 14/118 +/- 9 mmHg, p < 0.01 before vs. after treatment). Diltiazem-retard at 19:00 (n = 6) exerted greatest effect during daytime activity (152 +/- 7/139 +/- 6, p < 0.01) with inhibition of the morning BP rise. Diltiazem (t.i.d., n = 5) had the best effect during daytime activity (151 +/- 16/136 +/- 9, p < 0.05). However, in nondipper hypertensive patients, diltiazem (t.i.d., n = 8) had the most pronounced antihypertensive effects during nightly rest (144 +/- 12/127 +/- 12, p < 0.05). Evening medication with diltiazem retard appears to be more efficacious than the other dosage schedules.

Cardiac conduction with diltiazem and beta-blockade combined. A review and report on cases

Sinus arrest or atrioventricular block are rare but serious adverse effects of diltiazem. The risk of developing such adverse reactions may be somewhat exacerbated by concomitant beta-adrenergic blocker therapy. In patients with hypertension or coronary heart disease, combination therapy with diltiazem and a beta-blocker usually enhances therapeutic benefit relative to monotherapy, but adverse effects attributable to this combination, especially in patients with left ventricular dysfunction or latent cardiac conduction deficits, may be limiting. Therefore, such combination therapy may not be suitable in patients with atrioventricular block grade I, bradycardia or hypotension, and patients on the combined therapy should always have their blood pressure, heart rate and atrioventricular conduction on ECG monitored. If combination therapy with diltiazem and propranolol or metoprolol is commenced, or in the case of impaired renal function, an adjustment of the beta-blocker dosage may be required. Clinical studies on the combined use of diltiazem and beta-adrenergic blockers mostly concern the treatment of angina pectoris in patients with coronary heart disease. Although very few cases of severe bradycardia and conduction abnormalities have been reported in patients with uncomplicated hypertension on diltiazem and beta-blockade combination, there seems to be a potential for the occurrence of significant conduction disturbances with the combined treatment, and precautions should apply also for hypertensive populations.

Pharmacodynamics and pharmacokinetics of clentiazem and diltiazem in closed-chest anesthetized dogs

In the present study we investigated the relationship between pharmacodynamic and pharmacokinetic properties of the benzothiazepine-like calcium antagonists, clentiazem and diltiazem. Experiments were carried out in closed-chest anesthetized dogs, instrumented for hemodynamic recording and blood sampling. Clentiazem and diltiazem bolus injections (400 micrograms/kg) were administered intravenously, and subgroups of animals were sacrificed at 15, 30, 60, or 120 minutes Clentiazem and diltiazem plasma and myocardial levels were determined by high performance liquid chromatography (HPLC). Clentiazem elicited a more marked reduction in mean arterial pressure (-17% for clentiazem vs. -12% for diltiazem), along with an attenuation of the expected positive reflex chronotropic response. Pharmacokinetic analysis revealed that clentiazem had a greater volume of distribution (33 +/- 16 l vs. 15 +/- 9 l for diltiazem), while the half-life of elimination (t1/2 beta) was similar (55 +/- 21 minutes vs. 59 +/- 23 minutes). The kinetic disposition profile of both drugs was analyzed through myocardial/plasma concentration ratios. In the distribution phase (0-15 minutes), this ratio was similar (26 +/- 2 for clentiazem vs. 18 +/- 5 diltiazem), suggesting that the myocardium was not a preferential site of distribution for either drugs. Data collected within the elimination phase indicate significant myocardial retention for clentiazem; at the end of the study period, the myocardial/plasma concentration ratio was twofold higher for clentiazem. The observed retention of clentiazem in the myocardium may be responsible for attenuation of the baroreflex. Clentiazem increased potency was confirmed by the fact that its hypotensive and cardioinhibitory effects were observed at lower plasma concentrations.

Antihypertensive efficacy and safe use of once-daily sustained-release diltiazem in the elderly: a comparison with captopril. The Dilcacomp Study Group

The efficacy and safety of sustained-release diltiazem, 200-300 mg once daily was compared with that of captopril, 12.5-25 mg twice-daily, in 100 elderly patients (65-85 years old) with mild to moderate essential hypertension (supine diastolic blood pressure 95-115 mmHg). All patients received placebo for 2 weeks, followed by an 8-week double-blind period, and were randomized to either diltiazem (n = 50) or captopril (n = 50). Their blood pressure was measured at trough level at week 4 immediately before dosing, i.e. 24 h post diltiazem dose or 12 h post captopril dose. Also at week 4, in non-responders, diltiazem was increased from 200 to 300 mg once daily and captopril from 12.5 to 25 mg twice daily to achieve a target supine diastolic blood pressure reduction of at least 10 mmHg or a diastolic blood pressure below 90 mmHg. Supine diastolic blood pressure, at week 8, was significantly (P < 0.001) reduced from 102 +/- 1 to 90 +/- 1 mmHg with diltiazem and from 103 +/- 1 to 89 +/- 1 mmHg with captopril, bringing this parameter within normal limits for both groups. Supine systolic blood pressure was also significantly (P < 0.001) reduced. Target blood pressure was achieved in 68% of patients taking diltiazem and in 70% taking captopril. Distribution of adverse events was comparable in both groups; no significant changes in laboratory or electrocardiographic parameters occurred. Two serious events were reported with captopril: one sudden death and one cerebrovascular stroke. Sustained-release diltiazem once a day is a convenient, well tolerated, first line treatment for hypertension in the elderly, for whom the possibility of using two dose levels allows a close regimen adjustment, 200 mg being recommended as a starting dose.

Conversion from immediate-release to extended-release diltiazem in angina pectoris

This multicenter, open-label, single crossover study examined 195 patients taking an immediate-release diltiazem tablet as chronic stable angina therapy to determine if apparently logical methods of converting them to an extended-release, once-daily formulation were effective. Patients were converted from the immediate-release (Phase I) to an extended-release (Phase II) formulation of diltiazem on a mg-for-mg basis or, when a similar dose was not available, to the next higher 120 mg dose. Weekly angina occurrences and nitroglycerin use, exercise testing at the end of each phase, and ambulatory electrocardiographic monitoring (AEM) during the week prior to the exercise study were evaluated. There was a statistically significant decrease in angina frequency and nitroglycerin consumption during Phase II. In the exercise studies, there was an insignificant increase in time to 1 mm ST-segment depression and total exercise time associated with a statistically significantly lower end-exercise blood pressure and heart rate in Phase II. In those patients who had ischemia during either phase on AEM, total ischemic duration and ischemic episodes were insignificantly lower in Phase II. All observations were similar in the subgroup of patients who were converted mg-for-mg. Adverse reactions were equal. Thus, in converting patients from an immediate- to an extended-release diltiazem formulation for the treatment of symptomatic coronary artery disease, it is reasonable to convert directly to the same or, if not available, the next higher available dose of the extended-release preparation.

The Nordic Diltiazem Study (NORDIL). A prospective intervention trial of calcium antagonist therapy in hypertension

NORDIL--the Nordic diltiazem intervention study was started in September 1992. This trial is a prospective randomized open blinded-endpoint (PROBE) multicenter, parallel-group study conducted in Norway and Sweden. The study is designed to evaluate the potential preventive effects of diltiazem compared with conventional antihypertensive drug treatment. Primary endpoints are cardiovascular mortality defined as fatal acute myocardial infarction, fatal acute cerebrovascular disease (stroke), sudden death and other fatal cardiovascular disease as well as cardiovascular morbidity defined as myocardial infarction and cerebrovascular disease (stroke). Secondary endpoints are total mortality, the development or deterioration of ischaemic heart disease, congestive heart failure, atrial fibrillation, transient ischaemic attacks, diabetes mellitus and renal insufficiency. Male and female patients, aged 50-69, with primary hypertension are randomly allocated to therapy starting with either diltiazem (180-360 mg daily) or conventional treatment (diuretics or beta-adrenergic blockers). Add-on therapy in the conventional treatment group excludes all types of calcium antagonists. The goal of treatment will be a target diastolic blood pressure of < or = 90 mmHg or a 10% diastolic blood pressure reduction. The NORDIL study will allow the detection of a 20% difference in cardiovascular mortality between the two groups with a power of 80% at the 5% significance level (two-sided test). A total of 12,000 patients will be recruited from about 480 primary Health Care Centers or hospital based Hypertension Units. Patients will be treated for an average period of 5 years.

Comparative pharmacokinetics and pharmacodynamics of two marketed bid formulations of diltiazem in healthy volunteers

Cardizem SR and Bi-Tildiem were both approved in their respective countries on the basis of clinical trials demonstrating efficacy and safety in the treatment of angina pectoris. In this cross-over randomized study, we assessed whether these two sustained-release formulations of diltiazem have equivalent pharmacokinetic and pharmacodynamic profiles. Twenty-four young healthy male volunteers were hooked to Holters and ambulatory blood pressure monitors for 24 h to establish baseline systolic blood pressure (SBP), diastolic blood pressure (DBP), sinus rate and PR intervals. They then received a single dose of 120 mg of diltiazem from one formulation. The pharmacodynamic measurements were recorded for a further 24 h and blood samples were collected over 36 h for evaluation of diltiazem in plasma by a high-performance liquid chromatogrpahic (HPLC) method. The procedures were repeated with the alternate formulation after a 7 d wash-out. Pharmacokinetics showed statistically significant (p < 0.01) differences in AUC0-12 with means (+/- SD) of 519.2(+/- 172.8) and 429.6(+/- 147.2) ng h ml-1, AUC0-36 of 835.6(+/- 281.6) and 730.9 (+/- 271.5) ng h ml-1 and Cmax of 89.1(+/- 30.3) and 61.1(+/- 21.2) ng ml-1 for Cardizem SR and Bi-Tildiem, respectively. The only pharmacodynamic parameter showing a statistically significant difference in change from baseline between the two formulations was DBP with mean (+/- SD) change in AUC0-12 of -13.6(+/- 20.8) and +8.4(+/- 31.7) mm Hg h (p = 0.0135) and in AUC0-24 of -33.0(+/- 43.7) and -0.3(+/- 59.2) mm Hg h (p = 0.0463) for Cardizem SR and Bi-Tildiem, respectively. These findings suggest that assessment of efficacy of sustained-release formulations of diltiazem by bioequivalence could be misleading. They also confirm that a single dose of diltiazem does not elicit a significant pharmacodynamic response in healthy volunteers. Equivalence for such formulations should therefore be demonstrated by pharmacodynamic evaluation or clinical studies in a patient population.

Vasodilators during cerebral aneurysm surgery

The objective of this review is to review the anaesthetic implications of vasoactive compounds particularly with regard to the cerebral circulation and their clinical importance for the practicing anaesthetist. Material was selected on the basis of validity and application to clinical practice and animal studies were selected only if human studies were lacking. Hypotensive drugs have been used to induce hypotension and in the treatment of intraoperative hypertension during cerebral aneurysm surgery. After subarachnoid haemorrhage, cerebral blood flow is reduced and cerebral vasoreactivity is disturbed which may lead to brain ischaemia. Also, cerebral arterial vasospasm decreases cerebral blood flow, and may lead to delayed ischaemic brain damage which is a major problem after subarachnoid haemorrhage. Recently, the use of induced hypotension has decreased although it is still useful in patients with intraoperative aneurysm rupture, giant cerebral aneurysm, fragile aneurysms and multiple cerebral aneurysms. In this review, a variety of vasodilating agents, prostaglandin E1, sodium nitroprusside, nitroglycerin, trimetaphan, adenosine, calcium antagonists, and inhalational anaesthetics, are discussed for their clinical usefulness. Sodium nitroprusside, nitroglycerin and isoflurane are the drugs of choice for induced hypotension. Prostaglandin E1, nicardipine and nitroglycerin have the advantage that they do not alter carbon dioxide reactivity. Local cerebral blood flow is increased with nitroglycerin, decreased with trimetaphan and unchanged with prostaglandin E1. Intraoperative hypertension is a dangerous complication occurring during cerebral aneurysm surgery, but its treatment in association with subarachnoid haemorrhage is complicated in cases of cerebral arterial vasospasm because fluctuations in cerebral blood flow may be exacerbated. Hypertension should be treated immediately to reduce the risk of rebleeding and intraoperative aneurysmal rupture and the choice of drugs is discussed. Although the use of induced hypotension has declined, the control of arterial blood pressure with vasoactive drugs to reduce the risk of intraoperative cerebral aneurysm rupture is a useful technique. Intraoperative hypertension should be treated immediately but the cerebral vascular effects of each vasodilator should be understood before their use as hypotensive agents.

A new extended-release formulation of diltiazem HCl for the treatment of mild-to-moderate hypertension

Calcium-channel blockers are a safe and effective treatment modality and have been used extensively in the treatment of angina and hypertension. Dilacor XR capsules, a new extended-release formulation of diltiazem, has been developed for the treatment of hypertension. Dilacor XR (Rhône-Poulenc Rorer Pharmaceuticals Inc., Collegeville, PA) uses a novel drug delivery system, the Geomatrix (JAGO Research AG, Zollikon, Switzerland) controlled-release system, to deliver diltiazem at a constant rate for 24 hours. The rate of absorption is also slower. As doses of Dilacor XR were increased from 120 mg to 540 mg/day, there were disproportionate increases observed in area under the curve, maximum peak plasma concentration, minimum peak plasma concentration, and average peak plasma concentration. The efficacy data from two clinical trials have confirmed the established efficacy of diltiazem and the 24-hour efficacy of Dilacor XR in the control of mild-to-moderate hypertension. The incidence of adverse effects with Dilacor XR in doses as high as 540 mg/day was generally comparable to that of placebo. This new extended-release formulation of diltiazem should significantly facilitate blood pressure control because of better patient compliance with a once daily regimen.

Clinical experience with a once-daily, extended-release formulation of diltiazem in the treatment of hypertension

Although calcium channel blockers were only recently approved for antihypertensive therapy, 10 years of data have demonstrated their beneficial effects. Among the available calcium channel blockers, diltiazem hydrochloride appears to have a highly favorable side-effect profile. A new, extended-release formulation of diltiazem has been developed for the treatment of essential hypertension. The safety and efficacy of various once-daily doses of this new formulation were assessed in two multicenter studies. The first study was a dose-ranging trial of 275 patients with mild-to-moderate hypertension. Patients were randomly assigned to once-daily diltiazem (120, 240, 360, or 480 mg) or placebo for a 4-week, double-blind treatment period. A patient subgroup underwent ambulatory blood pressure monitoring (ABPM) twice. Once-daily diltiazem (dose range, 240-480 mg) significantly lowered trough systolic and diastolic blood pressure in a clearly dose-related fashion. ABPM results demonstrated consistent decreases in systolic and diastolic blood pressure throughout the 24-hour dosing interval. Dosages greater than or equal to 240 mg/day provided trough drug blood levels within the therapeutic range (i.e., greater than or equal to 40 ng/mL). The second study was a forced-escalation trail of 115 patients with mild-to-moderate hypertension. Patients were randomized to treatment with either placebo or escalating dosages of diltiazem (180 mg/day for 2 weeks, 360 mg/day for 2 weeks, and then 540 mg/day for 2 weeks). Statistically significant (p less than 0.01) reductions in supine systolic and diastolic blood pressure were observed with the 360 mg/day and 540 mg/day dosages. Dose escalations resulted in incremental blood pressure reductions and an increase in the percentage of responders. There was a significant correlation between diltiazem peak and trough plasma concentrations and antihypertensive effects in both studies, supporting the 24-hour efficacy of this extended-release formulation. Diltiazem administered once daily was found to be safe and well tolerated by the patients in these studies; adverse events were generally mild, with an incidence similar to placebo. Results indicate that this new extended-release formulation of diltiazem, administered once daily in doses greater than 120 mg, effectively lowers systolic and diastolic blood pressure in patients with mild-to-moderate essential hypertension.

The hypertensive patient. Not just a number

Treatment of both systolic-diastolic and isolated systolic hypertension in patients over age 65 has been shown to decrease subsequent cardiovascular morbidity and mortality. In the European Working Party on High Blood Pressure in the Elderly study, the number of morbid and mortal cardiovascular events prevented in the treatment group was 29/1,000 person-years, whereas in the Systolic Hypertension in the Elderly Program, the number was 55/1,000 person-years. This magnitude of reduction is substantial, but in the case of primary prevention in the elderly, a large number of patients must be treated to benefit relatively few. Better strategies of targeting treatment based on risk over and above that of high blood pressure are needed. Certainly, patients with more than one cardiovascular risk factor or evidence of end-organ damage should be treated more aggressively.

Relationship between the cardiovascular effects and both plasma and myocardial levels of clentiazem, a new benzothiazepine calcium antagonist, in anesthetized dogs

We evaluated the relationship between the cardiovascular effects of clentiazem (TA-3090), a new 1,5-benzothiazepine calcium antagonist with high lipophilicity, and both its plasma and myocardial concentrations. Anesthetized, open-chest dogs, instrumented for hemodynamic data recording and blood sampling, were divided into three groups treated with 15, 50, or 200 micrograms/kg of clentiazem, respectively, as an intravenous bolus. At the end of the protocol (240 minutes), myocardial samples were tested for clentiazem. The results indicated that the peripheral and coronary vasodilatory effects of clentiazem were dose dependent and closely related to its plasma concentrations. It was also observed that the minimal effective plasma concentration was in the range of 15-20 ng/ml. Sustained negative chronotropic effects were recorded at the highest dose only and were best related to the amount of clentiazem detectable in the myocardium, suggesting that myocardial clentiazem retention is a major factor governing its depressant cardiac impact.

Twenty-four hour ambulatory blood pressure profile of a new slow-release formulation of diltiazem in mild to moderate hypertension

Twelve patients with a mild to moderate essential hypertension were included in a double-blind, balanced, randomized placebo-controlled cross-over study to assess the efficacy and duration of action of a new slow-release formulation of diltiazem (300 mg) given once daily for 3 weeks. All office blood pressure measurements were done 24 hours after drug intake. In order to improve the accuracy of the trial, 24-hours non-invasive ambulatory blood pressure monitoring (Spacelabs 90207 system) were performed as well. Diltiazem significantly lowered supine and standing systolic and diastolic office blood pressure (by 16.9/12.7 mmHg and by 17.3/13.8 mmHg, respectively), without changing office heart rate. Diltiazem also significantly lowered ambulatory blood pressure measured over 24 hours, as well as ambulatory heart rate. The blood pressure lowering effect was most pronounced during the daytime period and did not reach statistical significance during the sleeping hours. The treatment was well tolerated, and there were no significant side effects. The results confirm the antihypertensive efficacy of diltiazem LP 300 mg once daily during the daytime and during the early morning blood pressure rise, without inducing nocturnal hypotension.

Impact of age, race, and obesity on hypertensive mechanisms and therapy

Despite the demonstrated efficacy of traditional antihypertensive therapy in reducing blood pressure, hypertension continues to be a major cause of cardiovascular disease morbidity and mortality. Stepped-care therapy is a nonphysiologic approach that, due to potential metabolic derangements and stimulation of undesirable reflex responses, may not substantially reduce the cardiovascular and renal complications associated with hypertension or improve long-term survival in many hypertensive patients. Because of fundamental hemodynamic differences related to the age, race, and weight of hypertensive patients, drug treatment often elicits varying responses. Certain classes of drugs are not only more effective but also more appropriate from a physiologic standpoint in specific types of patients. Therapy selection based in part on hemodynamic mechanisms and demographic patterns is a more rational approach to patient management and may contribute to a better overall outcome than has been observed with conventional treatment.

Gingival hyperplasia: a side effect of nifedipine and diltiazem

Currently, calcium channel blockers are being used increasingly for the treatment of hypertension in the elderly. Several case reports in the dental literature suggest that patients treated with the calcium channel blockers manifest gingival hyperplasia similar to that seen in patients taking phenytoin (Dilantin, Parke-Davis). A small study of 89 patients undertaken at the Westside Veterans Administration Medical Center, Chicago seems to indicate that nifedipine and diltiazem do indeed cause gingival hyperplasia. A total of 83% of the patients studied receiving nifedipine showed evidence of hyperplastic tissue and 74% of those on diltiazem were found to have hyperplastic tissue.

Once daily compared with twice daily administration of slow-release diltiazem as monotherapy for hypertension

We compared the efficacy of the antihypertensive drug diltiazem in a slow release formulation administered once daily with its twice daily administration as monotherapy in 34 patients with mild to moderate essential hypertension. All subjects received placebo for three weeks before the randomised, double blind, crossover study, and their supine diastolic blood pressure (BP) ranged from 95 mmHg to 115 mmHg. After the patients had received the placebo for three weeks diltiazem was titrated in the open label treatment to either 120 mg or 180 mg twice daily until the target BP level was achieved. After the open three weeks' of treatment with diltiazem twice daily patients were allocated randomly for either once daily or twice daily administration. After a six week, double blind period, the treatment was changed according to the crossover design. With a dose of 120 mg or 180 mg twice daily patients' supine and standing BP readings were significantly lower than when they took the drug once daily. In the subgroup (n = 19) with the maximum dose of diltiazem given twice daily and once daily BP levels were lower in those subjects on twice daily treatment than in those treated once a day with the same total daily dose, the differences being significant. Administration of diltiazem once a day in a slow release formulation was not as effective as a twice daily dose when the dose titration was greatest or when compared with the same dosage (240 mg x 1/day or 120 mg x 2/day).

Antihypertensive monotherapy with tablet (prompt-release) diltiazem: multicenter controlled trials

The tablet formulation of diltiazem has been available for the treatment of angina pectoris but has not been comprehensively evaluated in hypertension. This study's aim was to evaluate the efficacy, dose-response characteristics, and duration of action of tablet (prompt-release) diltiazem in mild to moderate hypertension. Three placebo-controlled trials were designed. The first (trial #1) evaluated the dose response of 120, 240, and 360 mg/day (q12h regimen) of diltiazem in parallel fixed-dose fashion using hourly blood pressures. The second (trial #2) evaluated a q12h titration from 240 to 360 mg/day, which could be switched to q8h. The third (trial #3) evaluated a q8h titration from 180 to 270 to 360 mg/day, followed by conversion to a q12h regimen. The goal was a supine diastolic blood pressure of less than 90 mmHg and 10 mmHg less than baseline. With doses of diltiazem increasing from 120 to 240 to 360 mg/day, there was a progressive decrease in the average mean arterial pressure, describing a dose response with 120 mg/day as the ineffective dose. The peak effect for each dose regimen was found at 6 hours, with significant reductions lasting over 10 hours in the 240 mg/day and 360 mg/day groups. Peak plasma concentrations occurred at 3 hours. The residual effect at the trough of the 240 mg/day and 360 mg/day doses was 48% and 53% of the peak effect, respectively. When titration was carried out on a q8h regimen, both systolic and diastolic blood pressures were significantly decreased. When the regimen was switched from q8h to q12h, the effect was not maintained.(ABSTRACT TRUNCATED AT 250 WORDS)

Sustained-release diltiazem: duration of antihypertensive effect

The antihypertensive activity of a sustained-release preparation of diltiazem (given each 12 hours) was assessed in 96 patients with supine diastolic blood pressure (BP) between 95 and 110 mm Hg in a multicenter, randomized, double-blind, placebo run-in, parallel-group trial comparing optimally titrated doses of diltiazem and placebo. The aim was to assess the onset of action as well as the extent and variability of BP control of this formulation during the 12-hour interval. Diltiazem was titrated from 120 mg bid to 180 mg bid as necessary to lower BP. At baseline, on the first day of titration, and at the end of 8 weeks, BP was evaluated at 0, 1, 2, 3, 4, 5, 6, 8, 10, and 12 hours after dosing. The onset of action was within 2 hours, and the effect was maintained throughout the 12-hour period. Mean BP for the diltiazem group at baseline was 154/101 mm Hg. At week 8, BP was 148/93 mm Hg at hour "0" (P less than .02 and P = .0001 for systolic and diastolic BP vs. placebo), 139/84 mm Hg at the nadir at hour 5 (P = .0001), and 149/91 mm Hg at the end of the 12-hour period (P less than .02 and P = .0001 for systolic and diastolic BP). Diltiazem was significantly more effective than placebo (P = .0001) with 50% of patients controlled to a diastolic pressure of less than 90 mm Hg at 7 of the 10 evaluation points, including the evaluation point of 12 hours post-dose.(ABSTRACT TRUNCATED AT 250 WORDS)

Antihypertensive effect of diltiazem in a slow-release formulation for mild to moderate essential hypertension

The antihypertensive efficacy and frequency of adverse reactions following administration of diltiazem in a new slow-release formulation were compared with placebo in 34 patients with mild to moderate essential hypertension in a randomized, double-blind, crossover study. After 6 weeks of treatment with diltiazem (240 or 360 mg/day), average supine blood pressure (BP) decreased from 165 +/- 21/101 +/- 5 mm Hg at baseline to 152 +/- 16/93 +/- 4 mm Hg compared with 160 +/- 19/100 +/- 7 mm Hg with placebo (p less than 0.01/p less than 0.001). Standing BP decreased from 162 +/- 20/107 +/- 6 mm Hg at baseline to 150 +/- 14/101 +/- 5 mm Hg compared to 159 +/- 18/107 +/- 8 mm Hg with placebo (p less than 0.01/p less than 0.001). The supine heart rate after diltiazem was 65 +/- 7 beats/min and after placebo 69 +/- 9 beats/min (p less than 0.01). There were no hematologic side effects. Only minor differences between diltiazem and placebo were observed in some of the biochemical laboratory values. Four patients were withdrawn due to side effects during treatment with diltiazem and 2 with placebo. Diltiazem in a slow-release formulation given twice a day lowered blood pressure significantly as monotherapy in patients with mild to moderate hypertension and was well tolerated.

Calcium channel blockers. Potential medical benefits and side effects

Calcium channel blockers are recently developed antihypertensive drugs. In terms of mechanisms of action, their specificity is not so well established as that of angiotensin converting enzyme inhibitors but is better understood than that for diuretics or adrenergic-inhibiting drugs. Calcium channel blockers were originally developed for treatment of angina but were found to lower arterial pressure as well. Three of them are now in wide use in the United States; their therapeutic spectrum in regard to type of hypertension is broad. Sublingual nifedipine has replaced intravenously administered vasodilators as immediate treatment of severe hypertension, and all three drugs, given orally, have been shown to be effective in mild, moderate, and severe hypertension. The three drugs available in this country are verapamil, diltiazem, and nifedipine. Pharmacological studies have shown that verapamil has the most negative chronotropic and inotropic effects of the three, with nifedipine producing the most vasodilation and having the potential for causing reflex tachycardia. Actually in practice, these various pharmacological differences have proved to have less significance than previously thought, and the drugs seem to have about equal antihypertensive effectiveness. Comparisons of calcium entry blockers with other drugs have shown them to be equally effective in whites as propranolol but more effective in blacks. Responsiveness appears to be related, as well, to pretreatment plasma renin activity and age. Thus, the antihypertensive effect is directly related to age and inversely related to plasma renin activity. The side effects mostly relate to vasodilation, reflex tachycardia, palpitations, headache, and edema; they are not frequent, and the drugs are well tolerated.

Antihypertensive therapy in the geriatric patient. I: A review of the role of calcium channel blockers

Animal and clinical studies have demonstrated the efficacy of calcium channel blockers in reducing blood pressure, especially in older patients whose hypertension is characterized by increased peripheral vascular resistance. Their chemical heterogeneity, which permits targeted therapy, as well as their minimal side effects, drug interactions, and clinical utility in numerous pathophysiologic states common to the elderly, enhance the suitability of calcium channel blockers in treating mild to moderate hypertension in this subgroup. This is particularly relevant for those patients who have concomitant conditions, such as diabetes, chronic obstructive pulmonary disease, or peripheral vascular disease, and for whom many of the more traditional antihypertensive drugs are either contraindicated or might cause a worsening of the disease.

Comparison of diltiazem and hydrochlorothiazide for treatment of patients 60 years of age or older with systemic hypertension

This randomized, double-blind, parallel design trial compared the efficacy and safety of monotherapy with either sustained-release diltiazem or hydrochlorothiazide in 61 men greater than or equal to 60 years of age with a diastolic blood pressure (BP) between 94 and 104 mm Hg. BP, heart rate, laboratory blood and urine tests, left ventricular wall thickness and mass index (as estimated by M-mode echocardiography) and rate and type of ventricular premature complexes (via ambulatory electrocardiographic monitoring) were determined before, during and after drug treatment. Both drugs produced highly significant (p less than 0.001) decreases in supine and upright systolic and diastolic BP. The mean dosages of diltiazem and hydrochlorothiazide used were 260 and 52 mg/day, respectively; at these dosages, 80% of diltiazem-treated versus 71% of hydrochlorothiazide-treated patients achieved goal reduction in BP (supine diastolic BP reduction of greater than 10 mm Hg and to less than 90 mm Hg). Both drugs were well tolerated, although hydrochlorothiazide therapy was associated with multiple biochemical abnormalities not seen with diltiazem. Neither drug affected left ventricular mass index or the rate of ventricular ectopic activity. Diltiazem and hydrochlorothiazide are both effective and safe agents when used as monotherapy in older patients with systemic hypertension unaccompanied by other clinically significant cardiovascular disease.

Diltiazem and captopril alone or in combination for treatment of mild to moderate systemic hypertension

The efficacy and safety of sustained-release diltiazem, 60 to 180 mg twice daily, was compared with that of captopril, 25 to 75 mg twice daily, alone and in combination, in 132 patients with mild to moderate essential hypertension (supine diastolic blood pressure [BP] 95 to 114 mm Hg). All patients received placebo for 4 to 6 weeks, followed by randomization to diltiazem or captopril during the double-blind monotherapy phase. Either study drug was titrated over 6 weeks to achieve a goal supine diastolic BP reduction of at least 10 mm Hg and a diastolic BP of less than 90 mm Hg. Patients achieving the goal BP reduction were maintained on monotherapy for an additional 8 weeks. Patients not achieving the treatment goal after 8 weeks with either drug alone received the other drug in combination, titrated to achieve goal BP response. Both drugs lowered BP significantly and, at the doses used, diltiazem had a greater effect on diastolic BP than did captopril. The mean changes from baseline at week 8 were -10.6 and -7.3 mm Hg, respectively, (p = 0.01). Goal BP was achieved in 38% of patients taking diltiazem monotherapy and in 34% of patients taking captopril monotherapy. There were no significant differences between diltiazem and captopril in diastolic or systolic BP reductions by race or age. The addition of alternate therapy for non-goal achievers at week 8 resulted in significant reductions in diastolic and systolic BP by week 16.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium metabolism, calcium-channel blocking agents, and hypertension management

Increasing evidence has suggested that a disturbance of cellular calcium metabolism may have a role in initiating and maintaining elevated systemic vascular resistance in essential hypertension. Controversy exists over whether calcium can alleviate or exacerbate the hypertensive process, and diversity of calcium metabolism in hypertensive patients has been proposed. Calcium-channel blocking agents are potent vasodilators capable of correcting the elevated systemic vascular resistance. Clinical studies have shown that these drugs have antihypertensive efficacy comparable to established agents. The elderly, blacks, and patients with low renin activity respond well to calcium-channel blockers. These drugs may also offer potential advantages over established antihypertensive agents in patients with other coexisting diseases. Sustained release formulations have been developed, and initial experience with long-term efficacy and tolerability is encouraging. The calcium-channel blockers may become first-line therapy for treatment of hypertension in selected patients.

Calcium channel antagonists. Part IV: Side effects and contraindications drug interactions and combinations

With the correct selection of drug and patient, the calcium antagonists as a group can be remarkably effective at relatively low cost of serious side effects. Almost all side effects are dose related. Minor side effects include those caused by vasodilation (flushing and headaches), constipation (verapamil), and ankle edema. Serious side effects are rare and result from improper use of these agents, as when intravenous verapamil (or diltiazem) is given to patients with sinus or atrioventricular nodal depression from drugs or disease, or nifedipine to patients with aortic stenosis. The potential of a marked negative inotropic effect is usually offset by afterload reduction, especially in the case of nifedipine which actually has the most marked negative inotropic effect. Yet caution is required when even calcium antagonists, especially verapamil, are given to patients with myocardial failure unless caused by hypertensive heart disease. Drug interactions of calcium antagonists occur with other cardiovascular agents such as alpha-adrenergic blockers, beta-adrenergic blockers, digoxin, quinidine, and disopyramide. The most marked interaction with digoxin is that with verapamil, which may raise digoxin levels by over 50%. Combination therapy of calcium antagonists with beta-blockers is increasingly common, and is probably safest in the case of dihydropyridines. Other combinations being explored are those with angiotensin-converting enzyme inhibitors and diuretics.

Monotherapy of hypertension with darodipine: a new calcium-channel blocker

Calcium-channel blockers are increasingly used as single agents for the treatment of essential hypertension. Following three weeks of single-blind placebo therapy, 43 patients with essential hypertension were randomized into four groups. Group 1 (10 patients) received placebo twice a day, Group 2 (13 patients) received darodipine (PY 108-068) 50 mg twice a day, Group 3 (9 patients) received darodipine 100 mg twice a day, and Group 4 (11 patients) received darodipine 150 mg twice a day. Patients were seen in the clinic weekly for 4 weeks. Clinical and laboratory evaluations were done on each patient. Darodipine caused a sustained decrease in the supine and standing systolic and diastolic blood pressure (p less than .001) and there were no significant pressure differences between the three drug dosages. The effects of the drug on heart rate were not consistent. Placebo had no effect on either blood pressure or heart rate. Side effects were few, mild, and consisted of headaches and peripheral edema, and did not necessitate discontinuation of the drug. No metabolic abnormalities were seen with either low or high doses of the drug. We conclude that: (1) darodipine is effective, safe, and well tolerated; (2) its antihypertensive effectiveness is similar at high and low doses, although the higher doses seemed to have a slightly greater effect on the diastolic arterial pressure; (3) the low dose may be preferable since side effects were dose related.

Diltiazem and left ventricular hypertrophy in renovascular hypertensive rats

The effects of diltiazem treatment (40-50 mg/kg/day orally for 8 weeks) of left ventricular hypertrophy on systemic and coronary hemodynamics and mechanical cardiac performance were investigated in renovascular hypertensive rats (Goldblatt, two-kidney, one clip). Systemic and coronary hemodynamics were determined by using radioactive microspheres in conscious, unrestrained rats. Mechanical performance was measured on isolated papillary muscle from the same animal. Nine treated hypertensive rats were compared with control groups: 12 untreated hypertensive and nine sham-operated rats. Diltiazem treatment led to an effective but incomplete control of blood pressure (from 208 +/- 5 mm Hg in the untreated hypertensive group to 155 +/- 3 mm Hg in the treated hypertensive group; p less than 0.01) associated with a significant but incomplete decrease of the left ventricular mass (from 3.10 +/- 0.19 mg/g in untreated hypertensive rats to 2.35 +/- 0.04 mg/g in treated hypertensive rats; p less than 0.01). A close correlation was found between left ventricular mass and systolic blood pressure in untreated, treated, and pooled groups (r = 0.84, p less than 0.001, n = 30). The left ventricular weight to systolic blood pressure ratio was equivalent in all three groups, so that the reduction of left ventricular mass in diltiazem-treated rats was commensurate with the reduction of blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium channel antagonists. Part III: Use and comparative efficacy in hypertension and supraventricular arrhythmias. Minor indications

The major antihypertensive mechanism of calcium antagonists is by decreasing the systemic vascular resistance, modified by the counter-regulatory responses of the baroreflexes and the renin-angiotensin-aldosterone system. In severe hypertension, the concept that calcium overload of the vascular myocyte could precipitate or aggravate peripheral vasoconstriction provides a logical basis for the use of these agents as first choice therapy; nifedipine, especially, has been well tested. As monotherapy for mild to moderate hypertension each of the three first-generation agents compares well with beta-blockers. Calcium antagonists may have a special role in the therapy of certain patient groups (elderly, black) or in those subjects whose life style involves intense physical or mental exertion (hemodynamics better maintained than with beta-blockade) or in patients with early end-organ damage such as left ventricular hypertrophy or renal insufficiency. However, the goal blood pressure may not be reached during monotherapy so that drug combinations may be required. Further indications for these compounds are as follows. Verapamil and diltiazem are frequently used in supraventricular tachycardias including acute and chronic atrial fibrillation. In the arrhythmias of the Wolff-Parkinson-White syndrome, there is the potential danger of provocation of anterograde conduction. Further indications for calcium antagonists, still under evaluation, include congestive heart failure (controversial), hypertrophic cardiomyopathy (verapamil), primary pulmonary hypertension (high doses required), Raynaud's phenomenon (nifedipine and diltiazem effective), peripheral vascular disease (proof not yet documented), cerebral insufficiency and subarachnoid hemorrhage (nimodipine promising), migraine, exertional bronchospasm, renal disease, atherosclerosis (experimental), and primary aldosteronism (nifedipine inhibits aldosterone release). Second-generation agents include dihydropyridines, such as nitrendipine, nicardipine, felodipine, amlodipine, nisoldipine, nimodipine, and isradipine. From these will be selected agents that are longer acting and provide higher vascular selectivity. New preparations of existing agents include slow-release formulations of nifedipine, verapamil, and diltiazem. Minor side effects include those caused by vasodilation (flushing and headaches), constipation (verapamil), and ankle edema. Serious side effects are rare and result from improper use of these agents, as when intravenous verapamil is given to patients with sinus or atrioventricular nodal depression from drugs or disease, or nifedipine to patients with aortic stenosis. The potential of a marked negative inotropic effect is usually offset by afterload reduction, especially in the case of nifedipine. Yet caution is required when calcium antagonists, especially verapamil, are given to patients with myocardial failure unless caused by hypertensive heart disease. Drug interactions of calcium antagonists occur with other cardiovascular agents such as alpha-adrenergic blockers, beta-adrenergic blockers, digoxin, quinidine, and disopyramide.(ABSTRACT TRUNCATED AT 400 WORDS)

Demographic considerations in the selection of antihypertensive therapy

Because of the growing number of antihypertensive agents that are suitable for initial therapy in mild and moderate hypertension, it is important to identify factors that influence the response to various medications. Although individual patient considerations, such as associated illnesses and potential side effects, are of primary importance in choosing therapy, the influence of demographic factors has received increasing attention. The effect of age, race and gender on the response to antihypertensive therapy will be examined. Several studies have indicated that the beta blockers and angiotensin converting enzyme (ACE) inhibitors are more effective in younger than in older patients. Conversely, there is a trend toward greater responses in older subjects to the diuretics and calcium antagonists. In the few studies available that have compared agents in various classes, it appears that diuretics, and probably calcium antagonists, are significantly more effective than beta blockers or ACE inhibitors in patients over 60 years of age. However, the interdrug differences in young patients are probably less important. With regard to race, the relative lack of effect of beta blockers and ACE inhibitors in blacks is well accepted; in comparative studies, diuretics proved significantly better. From the few available studies, it does not appear that the calcium antagonists are more potent in either racial group, but they may be superior to the beta blockers and ACE inhibitors in blacks. Far less information is available concerning differences in antihypertensive responses between men and women. There is some suggestion that women may be less responsive to beta blockers than men.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise capacity and hemodynamics in persons aged 20 to 50 years with systemic hypertension treated with diltiazem and atenolol

Hemodynamic responses and exercise capacity were studied during maximal exercise in 25 young hypertensive persons (mean age 40 years) taking placebo, diltiazem (mean 216 mg/day) and atenolol (mean 80 mg/day). The study was a crossover, double-blind, randomized trial, each medication period lasting 2 months. Sitting blood pressure (BP) was 160 +/- 19/109 +/- 8 mm Hg after run-in. Both drugs decreased BP significantly, diltiazem by 10/ 11 mm Hg and atenolol by 16/14 mm Hg (difference not significant between drugs). During exercise there were no differences among patients taking placebo, diltiazem and atenolol in peak workload and rating of perceived exertion. Atenolol significantly attenuated the increase in heart rate, BP and heart rate-BP product at each workload. Diastolic BP during exercise was significantly lower (6 to 10 mm Hg) during diltiazem therapy than during placebo at each workload. Thus, both diltiazem and atenolol decrease rest BP significantly without impairing exercise capacity.

Effects of diltiazem alone and combined with mefruside on cardiovascular response at rest and during exercise, carbohydrate metabolism and serum lipoproteins in patients with systemic hypertension

The antihypertensive effects of the calcium antagonist diltiazem, both alone and combined with the diuretic mefruside, were assessed over 14 months in 36 patients with essential hypertension. Patients received 180 or 270 mg/day; those with inadequate response were given 270 mg/day plus mefruside, 20 mg/day. Both monotherapy and combination therapy significantly reduced blood pressure (BP) at rest and during exercise. However, adding mefruside did not significantly decrease BP below that achieved with diltiazem alone. After 14 months of therapy, the percentage of responders (patients with at least 10% reduction in diastolic BP at rest) was 64% for all patients, 100% (by definition) for those receiving diltiazem alone and 47% for those receiving the combination. Diltiazem decreased heart rate by 6% (4 beats/min at rest) (p less than 0.05). Combined therapy with mefruside did not further reduce heart rate. There were few adverse effects and no undesirable metabolic effects with either monotherapy or combined therapy. Plasma renin activity, aldosterone levels, carbohydrate metabolism, serum lipoprotein levels and routine laboratory test results were unchanged in both groups at the end of the study. Thus, diltiazem is an effective antihypertensive agent and apparently the combination of diltiazem and mefruside does not potentiate the antihypertensive effect of diltiazem alone during long-term therapy.

Calcium channel blockers and cardiac surgery

Calcium channel blockers have an important role in the pharmacotherapy of cardiovascular disorders. These agents act by inhibiting the slow inward current into excitable cells, exert direct negative inotropic, chronotropic, and dromotropic activity, and are potent vasodilators. These direct effects are modified by reflex autonomic stimulation and by pathologic states. Serious adverse effects of the calcium channel blockers are most frequently observed in patients with ventricular dysfunction, conduction system disease, or concomitant beta blockade. Calcium channel blockers are indicated in the treatment of angina pectoris, supraventricular arrhythmias, and hypertension. The use of these agents in patients with hypertrophic cardiomyopathy, congestive heart failure, and pulmonary hypertension is investigational. The calcium channel blockers are gaining increased importance in the management of patients undergoing cardiac surgery. Verapamil is indicated for the treatment of post-cardiac-surgical atrial flutter and fibrillation; however, the calcium antagonists are not effective as prophylaxis against postoperative supraventricular arrhythmias. Laboratory studies have shown that drug interactions exist between calcium channel blockers and inhalational anesthetics and nondepolarizing neuromuscular blocking agents; clinical studies have demonstrated that these interactions are rarely significant. Perioperative coronary spasm can be effectively treated with the calcium channel blockers. The timing of calcium antagonist withdrawal prior to surgery is controversial, but continuation of therapy until surgery is usually safe. The clinical significance of platelet function inhibition by the calcium antagonists is unknown. Protection of ischemic myocardium by calcium channel blockers has been demonstrated. Important interactions between the calcium antagonists, hypothermia, and the ionic constituents of cardioplegia require further study before the role of these agents as adjuncts to clinical cardioplegia is defined. Expanded indications and the introduction of new calcium channel blockers will result in increased use of these agents in the future.

Diltiazem versus propranolol in essential hypertension: responses of rest and exercise blood pressure and effects on exercise capacity

Both beta-blocking and calcium channel-blocking drugs are being used with increasing frequency as initial therapy for essential hypertension. The present study was designed to compare the antihypertensive effects of a beta-blocking drug, propranolol, with a calcium channel-blocking drug, diltiazem, at rest and during upright bicycle exercise and to determine whether exercise capacity is altered by these therapies. Twenty-one patients with uncomplicated systemic hypertension and a diastolic blood pressure (BP) of 95 to 110 mm Hg without medication were randomly assigned to propranolol or diltiazem therapy in a double-blind manner. The total daily dosages were titrated as needed, from 160 to 480 mg of propranolol (mean 371 mg) and 120 to 360 mg of diltiazem (mean 307 mg) over 12 weeks, and the titrated dose was maintained for 4 additional weeks. Both drugs significantly reduced supine BP (from 149 +/- 14/101 +/- 4 to 136 +/- 17/89 +/- 10 mm Hg with propranolol and from 157 +/- 14/103 +/- 4 to 144 +/- 13/93 +/- 8 with diltiazem. Only diltiazem reduced BP during submaximal exercise, but both agents produced significant responses during maximal exercise. Diltiazem had no effect on maximal heart rate, exercise duration or O2 uptake, whereas propranolol reduced maximal VO2 from 27 +/- 6 to 22 +/- 6 ml/min/kg (p less than 0.01) and also shortened duration of exercise. Propranolol, despite its effects on heart rate, maintained the workload VO2 relation at submaximal loads, suggesting an increased oxygen delivery. However, these adaptive mechanisms appear to be insufficient during maximal effort.

Efficacy of sustained-release verapamil in chronic stable angina pectoris

The effectiveness of a sustained-release preparation of verapamil (verapamil-SR) was compared with the regular formulation of verapamil and with placebo in 12 patients with chronic stable angina pectoris. All patients completed an 8-week, double-blind, double-crossover, randomized protocol with 2-week treatment periods of verapamil-SR, 240 mg twice daily; regular-formulation verapamil, 120 mg 4 times daily; and 2 placebo therapies. The frequency of weekly anginal episodes was reduced from 7.6 +/- 10.0 with placebo to 3.1 +/- 4.2 after the regular formulation of verapamil (p = 0.09) and from 6.4 +/- 7.6 with placebo to 2.8 +/- 4.8 after verapamil-SR (p = 0.06). Treadmill time increased from 384 +/- 144 seconds during the first placebo phase to 468 +/- 138 seconds after the regular formulation of verapamil (p less than 0.01) and from 354 +/- 102 seconds during the second placebo phase to 462 +/- 138 seconds after verapamil-SR (p less than 0.01). Time to the onset of angina was similarly prolonged by formulations of verapamil. There were no significant adverse effects after 1 year in any patient taking verapamil-SR, 240 mg twice daily. Thus, a twice-a-day verapamil-SR dose regimen is safe and is as effective for treatment of angina of effort as the regular formulation given 4 times a day.