Calcium entry blockers for the treatment of severe hypertension and hypertensive crisis

Management of perioperative hypertensive urgencies with parenteral medications

BACKGROUND

Hypertension is the major risk factor for cardiovascular (CV) disease such as myocardial infarction (MI) and stroke. This risk is well known to extend into the perioperative period. Although most perioperative hypertension can be managed with the patient's outpatient regimen, there are situations in which oral medications cannot be administered and parenteral medications become necessary. They include postoperative nil per os status, severe pancreatitis, and mechanical ventilation. This article reviews the management of perioperative hypertensive urgency with parenteral medications.

METHODS

A PubMed search was conducted by cross-referencing the terms "perioperative hypertension," "hypertensive urgency," "hypertensive emergency," "parenteral anti-hypertensive," and "medication." The search was limited to English-language articles published between 1970 and 2008. Subsequent PubMed searches were performed to clarify data from the initial search.

RESULTS

As patients with hypertensive urgency are not at great risk for target-organ damage (TOD), continuous infusions that require intensive care unit (ICU) monitoring and intraarterial catheters seem to be unnecessary and a possible misuse of resources.

CONCLUSIONS

When oral therapy cannot be administered, patients with hypertensive urgency can have their blood pressure (BP) reduced with hydralazine, enalaprilat, metoprolol, or labetalol. Due to the scarcity of comparative trials looking at clinically significant outcomes, the medication should be chosen based on comorbidity, efficacy, toxicity, and cost.

Calcium antagonists

Calcium antagonists were introduced for the treatment of hypertension in the 1980s. Their use was subsequently expanded to additional disorders, such as angina pectoris, paroxysmal supraventricular tachycardias, hypertrophic cardiomyopathy, Raynaud phenomenon, pulmonary hypertension, diffuse esophageal spasms, and migraine. Calcium antagonists as a group are heterogeneous and include 3 main classes--phenylalkylamines, benzothiazepines, and dihydropyridines--that differ in their molecular structure, sites and modes of action, and effects on various other cardiovascular functions. Calcium antagonists lower blood pressure mainly through vasodilation and reduction of peripheral resistance. They maintain blood flow to vital organs, and are safe in patients with renal impairment. Unlike diuretics and beta-blockers, calcium antagonists do not impair glucose metabolism or lipid profile and may even attenuate the development of arteriosclerotic lesions. In long-term follow-up, patients treated with calcium antagonists had development of less overt diabetes mellitus than those who were treated with diuretics and beta-blockers. Moreover, calcium antagonists are able to reduce left ventricular mass and are effective in improving anginal pain. Recent prospective randomized studies attested to the beneficial effects of calcium antagonists in hypertensive patients. In comparison with placebo, calcium antagonist-based therapy reduced major cardiovascular events and cardiovascular death significantly in elderly hypertensive patients and in diabetic patients. In several comparative studies in hypertensive patients, treatment with calcium antagonists was equally effective as treatment with diuretics, beta-blockers, or angiotensin-converting enzyme inhibitors. From these studies, it seems that a calcium antagonist-based regimen is superior to other regimens in preventing stroke, equivalent in preventing ischemic heart disease, and inferior in preventing congestive heart failure. Calcium antagonists are also safe and effective as first-line or add-on therapy in diabetic hypertensive patients. Heart rate-lowering calcium antagonists (verapamil, diltiazem) may have an edge over the dihydropyridines in post-myocardial infarction patients and in diabetic nephropathy. Thus, calcium antagonists may be safely used in the management of hypertension and angina pectoris.

Diagnosis and management of hypertensive emergencies

It has been estimated that approximately 600,000 to 800,000 Americans will develop a hypertensive crisis (Calhoun and Oparil, 1990). Although such numbers represent only about 1% of the estimated 60 million Americans with hypertension, hypertensive crisis often constitutes a major medical emergency, necessitating a focused, assertive, and reasoned therapeutic intervention. When such patients are seen in the emergency department or in a physician's office with a critical elevation in blood pressure (BP), appropriate and efficacious management is essential to avoid catastrophic injury to vital target organs, including the central nervous system, the heart, and the kidneys. Delays in initiating effective therapy or, equally important, overzealous therapy leading to a too-rapid reduction in BP can produce severe complications involving these target organs. This article reviews the spectrum of clinical syndromes that comprise hypertensive emergencies, highlighting 2 to illustrate the complexities of clinical presentation and management. The newly advocated treatment guidelines based on the category of acute severe hypertension (including asymptomatic hypertensive urgencies) are also considered, as are therapeutic strategies utilizing currently available antihypertensive agents.

Regulation of blood pressure with calcium-dependent dopamine synthesizing system in the brain and its related phenomena

The effects of calcium on blood pressure regulation remain controversial. Although the mechanism by which calcium increases blood pressure when it is given intravenously and acutely has been elucidated, that by which calcium reduces blood pressure when it is supplemented chronically and slightly through daily diet is unclear. From a number of animal experiments concerning the effects of calcium on blood pressure, we believe that calcium ions have two separate roles in the regulation of blood pressure through both central and peripheral systems: (1) calcium ions reduce blood pressure through a central, calcium/calmodulin-dependent dopamine-synthesizing system and (2) calcium ions increase blood pressure through an intracellular, calcium-dependent mechanism in the peripheral vasculature. These concepts were applied to elucidate the mechanisms underlying hypertension in spontaneously hypertensive rats (SHR) and changes in blood pressure in other experimental animals, and the following conclusions were reached. The decrease of the serum calcium level in spontaneously hypertensive rats (SHR) causes a decrease in calcium/calmodulin-dependent dopamine synthesis in the brain. The subsequent low level of brain dopamine induces hypertension. The increase in susceptibility to epileptic convulsions and the occurrence of hypertension in epileptic mice (El mice) may be linked through a lowering of calcium-dependent dopamine synthesis in the brain, and epilepsy and hypertension may be associated. Exercise leads to increases in calcium-dependent dopamine synthesis in the brain, and the increased dopamine levels induce physiological changes, including a decrease in blood pressure. Cadmium which is not distinguished from calcium by calmodulin, activates calmodulin-dependent functions in the brain, and increased dopamine levels may decrease blood pressure. In this report, our studies are considered in light of reports from many other laboratories.

Hemodynamic effects of oral nifedipine in preeclamptic hypertensive emergencies

OBJECTIVE

Our purpose was to evaluate the hemodynamic effects of oral nifedipine in preeclamptic hypertensive emergencies.

STUDY DESIGN

A prospective observational study of the hemodynamic effects of oral nifedipine was conducted with severely preeclamptic patients receiving magnesium sulfate infusion during a hypertensive emergency. Patients were eligible for the study if systolic blood pressure was > or = 170 m Hg or the diastolic blood pressure was > or = 105 mm Hg on repeat measurements 15 minutes apart at > or = 24 weeks' gestation. Nifedipine was given with an initial dose of 10 mg orally followed by 20 mg orally every 20 minutes until systolic blood pressure was > 160 mm Hg and the diastolic blood pressure was < 100 mm Hg, or for a total of five doses. Patients were hemodynamically monitored in the lateral recumbent position by thoracic electrical bioimpedance before during, and after oral nifedipine dosing. Cardiac index, systemic vascular resistance index, mean arterial pressure, heart rate, and stroke index were all recorded at baseline and during treatment. Data were analyzed by analysis of variance for repeated measures (alpha 0.05) and paired t tests, baseline versus 15 minutes (alpha 0.01).

RESULTS

Ten severely preeclamptic patients at 33.2 +/- 3.0 (mean +/- SD) weeks' gestation were enrolled in the study. Mean arterial pressure measurements taken at baseline, 0.25, 0.5, 1, and 4 hours were 133 +/- 10, 119 +/- 8, 109 +/- 8 89 +/- 12, and 100 +/- 13 mm Hg (mean +/- SD, p < 0.0001, analysis of variance repeated measures). Cardiac index increased over time (p = 0.0011, analysis of variance repeated measures). There was no significant effect on maternal heart rate or stroke index. No periodic fetal heart rate changes were noted. One patient had nausea.

CONCLUSION

Oral nifedipine appears to be an effective antihypertensive agent in preeclamptic hypertensive emergencies. A steady decrease in mean arterial pressure, systemic vascular resistance, and a mirrored increase in cardiac index are noted.

Effects of amlodipine on 24-hour ambulatory blood pressure profiles, electrocardiographic monitoring, and left ventricular mass and function in black patients with very severe hypertension

In a 3-month, open-label study, 54 consecutive black patients with very severe hypertension were treated with amlodipine. Very severe hypertension was defined as an average sitting diastolic blood pressure (BP) > or = 115 mmHg and < or = 140 mmHg as a mean of 10 readings over a 30-minute period using an automatic BP measuring device and a mean 24-hour diastolic ambulatory blood pressure (ABP) > or = 110 mmHg and < or = 140 mmHg). Serial changes in 24-hour ABP and electrocardiographic monitoring, left ventricular (LV) mass index, and LV systolic function were evaluated. Mean 24-hour ABP was reduced from 181 +/- 14/119 +/- 6 to 140 +/- 15/92 +/- 9 mmHg at 3 months (P < 0.0001). Target BP (mean 24-hour diastolic ABP < 90 mmHg) was achieved in 35% of the patients. The reduction in BP was sustained for 24 hours after drug administration. Simultaneous BP measurements using the automatic BP measuring device were significantly different from the ABP measurements before and after treatment, suggesting a marked "white coat" pressor effect. At baseline, frequent or complex ventricular arrhythmias (> 30 ventricular extrasystoles per hour, ventricular couplets) were present in 2 (4%) patients, with no significant change after treatment. Left ventricular mass index regressed from 140 +/- 50 to 111 +/- 30 g/m2 at 3 months (P < 0.03); LV performance was not adversely affected. Adverse effects were few and tended to disappear during the treatment period. All of the clinical laboratory parameters tested remained unchanged. In this group of patients, treatment with amlodipine showed a marked and sustained antihypertensive action as demonstrated by 24-hour ABP monitoring, and was well tolerated and associated with LV mass regression without adverse effect on systolic cardiac function. Further, a low rate of complex ventricular arrhythmias was documented.

Management of hypertensive urgencies and emergencies

Hypertensive emergency is a condition in which there is elevation of both systolic and diastolic blood pressure with the presence of acute target organ disease. Hypertensive urgency is a condition where the blood pressure is elevated (diastolic > 120 mmHg) with the absence of acute target organ disease. Hypertensive emergencies are best managed with parenteral drugs and careful intraarterial blood pressure monitoring. Hydralazine has been widely used in treatment of hypertension in eclampsia and preeclampsia, and its safety has been demonstrated in these patients. Sodium nitroprusside (SNP) has the most reliable antihypertensive activity, which begins immediately after its administration and ends when the infusion is stopped. As with diazoxide, it should be used with caution in patients with impaired cerebral flow. SNP is the preferred drug in obtaining controlled hypotension in patients undergoing neurovascular surgery. Intravenous nitroglycerin is useful in patients prone to myocardial ischemia, but should be avoided in patients with increased intracranial pressure. Esmolol is effective in controlling both supraventricular tachyarrhythmias and severe hypertension. Its short onset of duration of action make it useful in the emergent setting, but because of its negative inotropic effect its use should be avoided in patients with low cardiac output. Verapamil should not be used in patients with preexisting conduction abnormalities. Nicardipine is a potent arteriolar vasodilator without a significant direct depressant effect on myocardium. As with other afterload reducing agents, it should not be used in patients with severe aortic stenosis. Because angiotensin-converting enzyme (ACE) inhibitors generally cause cerebral vasodilatation, enalaprilat may be particularly beneficial for patients who are at high risk of developing cerebral hypotensive episodes secondary to impaired cerebral circulation. Fenoldopam, a selective post-synaptic dopaminergic receptor (DA1) has been shown to be effective in treating severe hypertension with a lower incidence of side effects than SNP. Hypertensive urgencies can usually be managed with oral agents. Oral nifedipine, captopril, clonidine, labetalol, prazosin, and nimodipine have all been shown to be effective in these situations.

Single-dose sublingual nifedipine as the only treatment in hypertensive urgencies and emergencies

One hundred and eighteen patients with hypertensive urgencies and emergencies and diastolic blood pressure (DBP) at least 120 mm Hg by the cuff method were seen at the Emergency Care Department; none had received calcium channel blockers during the previous twelve hours. Patients with DBP of 120 to 139 mm Hg received 10 mg of sublingual nifedipine; patients with left ventricular hypertrophy or failure, renal disease, hypertensive encephalopathy, angina, papilledema, or a DBP over 140 mm Hg received 20 mg of the drug. The criterion for control was the achievement of a DBP of 100 mm Hg or less within sixty minutes of receiving sublingual nifedipine and maintenance of the effect until discharge. Control was achieved in all patients; a sixty-three-year-old man died of a brain hemorrhage after pulmonary edema and a DBP of 210 had been controlled; the other 117 were discharged to their attending physicians, either as outpatients or to a hospital ward. No patient developed hypotension, clinical or electrocardiographic signs of myocardial ischemia, or clinical signs of neurologic dysfunction. Practical, fast, safe, and dependable control of hypertensive urgencies and emergencies has made sublingual nifedipine the treatment of choice of such patients in the Emergency Care Department.

The use of calcium channel blockers in obstetrics and gynecology; a review

Since their introduction, calcium channel blockers gained wide use in the treatment in various fields of medicine. Calcium channel blockers were shown to inhibit contractions of the pregnant and nonpregnant uterus, and lately their properties have made it, theoretically, an ideal candidate for the use in severe pregnancy-induced hypertension: it is effective in lowering blood pressure, has a fast and long-standing action, may be conveniently administered via the oral route, and it is not associated with serious side effects.

Rapid-acting parenteral antihypertensive agents

Parenteral antihypertensive agents are useful in those clinical situations where rapid reduction of blood pressure is necessary or where treatment with oral antihypertensive medications is not feasible. Given the diverse selection of parenteral antihypertensive drugs now available, therapy can be individualized. The presence of concurrent diseases will often influence the decision-making process regarding choice of an agent. Complications of parenteral antihypertensive therapy can arise from the intrinsic properties of the various drugs or the development of severe hypotension. Gradual lowering of blood pressure, in conjunction with careful clinical evaluation, will minimize the risks of acute parenteral antihypertensive therapy. Given that parenteral antihypertensive therapy often needs to be replaced by oral therapy, those drugs that can be used both parenterally and orally may have an advantage.

Intravenous nicardipine in severe systemic hypertension

Sixty-six patients with severe hypertension were treated with intravenous nicardipine in 3 separate protocols. Each protocol had a common end point: Diastolic blood pressure would either reduce 25 mm Hg or measure below 95 mm Hg. Each of the 66 patients studied attained the desired clinical response end point. Intravenous nicardipine produced a gradual reduction in blood pressure, was effective in maintaining blood pressure control during constant infusion and had few undesirable effects. These observations suggest that intravenous nicardipine maybe a useful addition to a limited number of therapeutic agents currently available to the physician for treatment of hypertensive urgencies.

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.

Intravenous nicardipine for the treatment of severe hypertension

PURPOSE

Severe hypertension responds to treatment with nifedipine given orally or sublingually. Nicardipine hydrochloride, a water soluble dihydropyridine analogue similar to nifedipine, has less of a negative ionotropic effect and produces less reflex tachycardia than nifedipine. Our purpose was to assess the antihypertensive efficacy and safety of intravenous nicardipine in a group of patients with severe hypertension (defined as a supine diastolic blood pressure of more than 120 mm Hg).

PATIENTS AND METHODS

Eighteen patients with severe hypertension received treatment with intravenous nicardipine. Nicardipine titration was performed using doses of 4 to 15 mg/hour to achieve therapeutic goal (diastolic blood pressure 95 mm Hg or less or decrease in diastolic blood pressure of more than 25 mm Hg). After this therapeutic end-point was reached, patients received maintainance therapy with nicardipine for varying lengths of time: one hour (Group I), six hours (Group II), or 24 hours. When blood pressure control was lost, patients in Groups I and II entered a second maintenance period lasting a maximum of 24 hours. Onset and offset of action of nicardipine at various infusion rates and times of infusion were measured.

RESULTS

Onset time to achieve therapeutic response was rapid at 15 mg/hour (0.31 +/- 0.13 hours) when compared with lower doses (1.11 +/- 0.36 hours at 4 mg/hour; 0.54 +/- 0.09 hours at 5 mg/hour; 0.52 +/- 0.09 hours at 7 to 7.5 mg/hour). Those who showed a therapeutic response received maintenance infusions with nicardipine for one (n = 7), six (n = 6), or 24 (n = 5) hours. Sustained blood pressure control at a constant rate of nicardipine infusion was seen in all patients during the maintenance period. After discontinuation of nicardipine, the time for offset of action (increase in diastolic blood pressure of 10 mm Hg or more) was independent of duration of infusion. Decreases in both systolic and diastolic pressures correlated well with plasma nicardipine levels. Heart rate increased by about 10 beats/minute, but this increase did not correlate with plasma nicardipine levels. Side effects were minimal, consisting of headache and flushing. In seven patients, local phlebitis developed at the site of infusion. This occurred after at least 14 hours of infusion at a single site, and the incidence can probably be reduced by shortening the infusion time at a single site.

CONCLUSION

Nicardipine appears to be a safe and effective drug for intravenous use in the treatment of severe hypertension.

Calcium channel blockers in systemic hypertension

Alterations in transmembrane flux of calcium ions may be playing a role in the pathophysiology of systemic hypertension. Calcium channel blockers have been shown to be effective antihypertensive drugs with excellent safety profiles. They are efficacious in the long term treatment of systemic hypertension in all population subgroups, and have special applicability for treating patients with hypertensive urgencies and individuals with concomitant diseases such as angina pectoris and arrhythmias.

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)

Nitrendipine in severe hypertension. Satellite symposium on calcium antagonists

We report the results of a multicenter trial in which nitrendipine, alone or in combination with a diuretic, a beta-blocker, or both, was administered to 114 patients with severe hypertension (greater than or equal to 115 mm Hg). Nitrendipine was titrated in doses of 5 to 30 mg b.i.d. If blood pressure was not controlled with nitrendipine alone, hydrochlorothiazide or propranolol or both were added. After a mean of 29 days in the study, 96 (90%) of 107 patients reached the initial goal of therapy; in 44 (41%) given nitrendipine alone the mean decrease in supine blood pressure was 38/25 mm Hg. After a mean of 91 days, 69 (72%) of 96 patients achieved the final goal of therapy; in 24 (25%) patients given nitrendipine alone the mean supine blood pressure decrease from baseline was 49/33 mm Hg. Falls in blood pressure were comparable in the patients given drug combinations. Seventy-two of 114 patients given study drug(s) had adverse experiences; headache and edema were the most frequent complaints. Only four patients dropped out of the study because of adverse effects. Most abnormal laboratory values occurred when nitrendipine was given with hydrochlorothiazide or propranolol or both. Analysis of severely hypertensive patients followed up in our Virginia center revealed continued control of blood pressure after long-term follow-up (43 +/- 3 [SD] months). Average supine blood pressure was reduced from 180/121 +/- 21/5 to 140/90 +/- 16/9 (SD) mm Hg (p less than 0.001). It was concluded that the calcium antagonist nitrendipine, alone or in combination with a diuretic or beta-blocker or both, is effective in the treatment of severe hypertension.

Multicenter comparison of the nifedipine gastrointestinal therapeutic system and long-acting propranolol in patients with mild to moderate systemic hypertension receiving diuretics. A preliminary experience

The efficacy and safety of nifedipine in a gastrointestinal therapeutic system (GITS) push-pull osmotic pump formulation was compared with long-acting propranolol in 49 patients with mild to moderate hypertension already receiving diuretics. Using a two-week placebo run-in, double-blind study design, patients were randomly assigned to receive nifedipine GITS (n = 24) in doses of 30 mg, 60 mg, or 90 mg once daily; or long-acting propranolol (n = 25) in doses of 80, 160, or 240 mg once daily. Previous diuretic therapy was continued. Sitting and five-minute standing blood pressure and heart rate measurements were made 24 hours after dosing. At the endpoint of treatment, both nifedipine GITS and sustained-release propranolol reduced blood pressure compared with placebo (p less than 0.001) in the sitting and standing positions. Nifedipine GITS was more effective in lowering standing systolic blood pressure than was propranolol (p less than 0.02). Propranolol caused a greater reduction in resting heart rate than did nifedipine GITS (p less than 0.003). Both drugs were well tolerated. Nifedipine GITS is an effective and safe once-daily drug for use in patients with hypertension who are already receiving diuretics, may be more effective than sustained-release propranolol, and may be better tolerated than conventional nifedipine capsules.

Sustained-release diltiazem compared with atenolol monotherapy for mild to moderate systemic hypertension

The daily administration of 240 to 360 mg of diltiazem lowered blood pressure in a dose-related pattern similar to that seen in patients taking a daily dosage of 50 to 100 mg of atenolol. Sustained-release diltiazem was administered twice daily and atenolol once. Goal blood pressure was defined as less than 90 mm Hg or a reduction of greater than or equal to 10 mm Hg for patients with baseline pressures of 95 to 99 mm Hg in the supine position and was achieved in 60% of diltiazem-treated and 63% of atenolol-treated patients. The mean diltiazem dosage at the end of the study was 329 mg daily; for atenolol it was 80 mg daily. Adverse reactions considered possibly or probably drug related were reported by 26% of diltiazem patients and 38% of atenolol patients. Although both drugs were associated with a slower heart rate, atenolol patients showed a significantly greater negative chronotropic effect. Diltiazem, in a sustained-release form taken twice daily, is as effective as atenolol as a sole antihypertensive agent. It has a favorable side-effect profile and may be a useful alternative antihypertensive medication compared with existing beta-blocker therapy with atenolol.

Nifedipine in hypertensive emergencies: a prospective study

Hypertensive emergencies usually present to the emergency department. Nifedipine was administered to 15 patients presenting to the emergency department with a diastolic blood pressure greater than 120 mm Hg with chest pain, shortness of breath, or focal neurological symptoms. Average blood pressure on entry was 215/134.9 mm Hg and decreased to 158/88 mm Hg over a two-hour period. No patient had any worsening of symptoms or suffered deleterious effects. All patients with pulmonary edema or chest pain noted prompt improvement in symptoms. One patient became hypotensive without clinical significance. Two patients failed to respond to nifedipine and were treated with nitroprusside. Nifedipine appears to be safe and effective in the management of hypertensive crises.

Current management of hypertensive emergencies

A number of potent and rapidly acting pharmacological agents are available to achieve safe, rapid, and controlled blood pressure reduction in most hypertensive crises. While sodium nitroprusside remains the drug of choice in many hypertensive emergencies, several newer agents are now available that may prove to be acceptable alternatives in the management of certain cases. Glyceryl trinitrate (nitroglycerin) and labetalol may be advantageous in patients with significant coronary artery disease. When adequate facilities to monitor continuous infusion of sodium nitroprusside are not immediately available, the intermittent minibolus administration of diazoxide or labetalol or the use of sublingual or oral nifedipine prove useful. A thorough knowledge of the pharmacological properties and proper indications of the currently used agents is essential for optimum management of the critically ill hypertensive patient.

Calcium modulators: future agents, future uses

The calcium modulators have been a significant therapeutic advancement for the treatment of angina. Structural analogs of verapamil and nifedipine have been synthesized, as have structurally unique compounds. As the role of calcium in body processes is further elucidated, the efficacy of the calcium modulators is being evaluated for numerous disorders. It is anticipated that the newly synthesized compounds will have specificity toward particular body processes, thus providing efficacy with minimal side effects.

Rectal administration of nifedipine: haemodynamic effects and pharmacokinetics in hypertensives

The haemodynamic effects and pharmacokinetics of nifedipine suppositories, used mainly for hypertensive emergencies, were studied in 10 severely hypertensive patients. Following rectal administration, significant hypotensive effects occurred after 0.5 h and lasted until 7 h after administration. The mean (+/- SE) maximum decreases in systolic and diastolic blood pressures 1.5 h after administration were: systolic, 61.8 +/- 7.9 mmHg (P less than 0.001); and diastolic, 30.8 +/- 4.0 mmHg (P less than 0.001). No serious side-effects were reported and heart rate did not change significantly. Mean nifedipine concentration in the blood peaked at 52.4 ng/ml, 1 h after administration and, after 7 h, was still 14.3 ng/ml which is higher than the minimum plasma concentration required for hypotensive effects to occur. There was a close correlation between nifedipine concentration in the blood and hypotensive effects. These results indicate that rectal administration of nifedipine should be regarded as a useful alternative treatment in hypertensive emergencies.

Noncardiac surgery in the patient with heart disease

Optimal care of the patient with heart disease undergoing noncardiac surgery requires that the members of the surgical team, including anesthesiologist, internist-cardiologist, and surgeon, be familiar with the cardiovascular response to surgery, preoperative cardiac risk stratification, and the unique pathogenesis of cardiac complications that may occur in the perioperative period. Preoperative evaluation and computation of cardiac risk, anesthetic considerations, along with perioperative care of the patient with ischemic heart disease, valvular heart disease, congestive heart failure, arrhythmias and conduction disorders, and hypertension is discussed.

Calcium channel blockers and treatment of hypertension

Over the past years, research efforts have been focused on the pathophysiologic role of calcium ions, and the implication for the potential role of calcium channel blockers in the management of essential hypertension. Numerous studies have shown that nifedipine and verapamil are effective antihypertensive agents, initial experience with diltiazem is also encouraging. The magnitude of blood pressure reduction with these drugs is related to the pre-treatment blood pressure. In refractory hypertension, combination with other antihypertensive agents provide additive effect. In the elderly population and in patients with ischemic heart disease, supraventricular arrhythmia, bronchospastic disease, peripheral vascular disease or diabetes mellitus, the calcium channel blockers offer potential advantages over other antihypertensive agents. Experimental studies also suggest that these drugs may reverse ventricular hypertrophy. When long-term safety with these drugs is documented from well-controlled clinical trials, the calcium channel blockers may be our first line of therapy for the management of hypertension.

Diuretics versus calcium-channel blockers in systemic hypertension: a preliminary multicenter experience with hydrochlorothiazide and sustained-release diltiazem

The safety and efficacy of sustained-release diltiazem 120 to 180 mg, 2 times a day, were compared with hydrochlorothiazide 25 to 50 mg, 2 times a day, and the combination of diltiazem and hydrochlorothiazide in 56 patients with mild to moderate hypertension (supine diastolic blood pressure between 95 and 114 mm Hg) using a placebo-controlled, parallel-design protocol. Data from an additional 21 patients were evaluated for safety only. The data reported herein represent the preliminary experience from a larger 200-patient multicenter study. All patients received placebo for 4 weeks, followed by either hydrochlorothiazide or diltiazem titrated to achieve a diastolic blood pressure reduction of greater than or equal to 10 mm Hg to reach a goal supine diastolic blood pressure of less than 90 mm Hg. Patients not achieving the treatment goal received hydrochlorothiazide plus diltiazem. At week 14, on maintenance monotherapy, diltiazem and hydrochlorothiazide produced comparable reductions in blood pressure from placebo baseline (160.3 +/- 24.3/101.7 +/- 5.5 to 145.2 +/- 24.1/89.8 +/- 7.4 mm Hg with diltiazem, 156.0 +/- 15.6/103.7 +/- 4.7 to 134.1 +/- 12.5/89.2 +/- 9.5 mm Hg with hydrochlorothiazide, p less than 0.001 for both). Diltiazem and hydrochlorothiazide achieved goal blood pressure in 42% and 45% of patients, respectively. The effects in responders were sustained for 6 months. In patients who did not achieve the treatment goal, 63% responded to diltiazem plus hydrochlorothiazide.No clinically significant postural hypotension was observed on any regimen. Heart rate was slightly lower with diltiazem than with hydrochlorothiazide. Adverse effects were minimal with diltiazem, hydrochlorothiazide and diltiazem plus hydrochlorothiazide but more hypokalemia occurred with hydrochlorothiazide.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium-channel blockers in acute hypertension

The acutely hypertensive patient may present with a broad spectrum of dysfunction. Given the wide variety of signs and symptoms, clinical settings, pathophysiological mechanisms, and type of end organ dysfunction, there is no ideal antihypertensive agent. In selecting an agent for treating such patients, the physician must consider efficacy in a variety of settings, rapidity of onset of action, duration of action, and ease of administration. In addition, one should keep in mind the risk of producing hypotension, the contraindication profile, the side-effect profile, and the cost and long-term usefulness of the agent. In this review, the calcium channel blockers verapamil and nifedipine are compared with drugs such as nitroprusside, diazoxide, hydralazine, labetalol, and clonidine. Verapamil, by intravenous administration, has a rapid onset of action, a reasonable duration of effect, a good side-effect profile, and appears to be useful on a long-term basis. Nifedipine, by oral or buccal administration, is useful in a variety of settings and had a rapid onset of action and reasonable duration of effect. In addition, nifedipine rarely causes hypotension, has minimal contraindications, an excellent side-effect profile, reasonable cost, and long-term utility. There is now extensive worldwide experience with verapamil and nifedipine in acute hypertension. They compare favorably with currently used agents.

Control of hypertension with nifedipine in the setting of aortic dissection

We report a 61-year-old man with dissection of the descending aorta and hypertension in whom medical management with beta-blocking antihypertensives was precluded by a history of asthma. The calcium channel blocker nifedipine was successfully employed in this setting and the rationale for its use is discussed.