Efficacy of sublingual nifedipine in the acute treatment of systemic hypertension

Radionuclide monitoring of left ventricular function after sublingual nifedipine administration at rest and during moderate physical activity

BACKGROUND

This study investigates the acute effects of nifedipine administration on left ventricular (LV) function in patients with different degrees of heart failure at a fixed heart rate under resting conditions and during moderate physical activity.

METHODS AND RESULTS

Eleven patients with non-rate-responsive DDD pacemakers were studied. According to baseline LV ejection fraction, patients were divided into 2 groups: 6 patients with an ejection fraction of less than 50% (group 1) and 5 patients with an ejection fraction of 50% or more (group 2). LV function was monitored by a radionuclide system (Vest) at rest and during moderate physical activity (10-minute walk test) before and after sublingual nifedipine administration (10 mg). In all patients, both the systolic blood pressure and diastolic blood pressure were significantly reduced (P <.05) 6 minutes after nifedipine administration. In group 1, end-diastolic volume and ejection fraction decreased after 3 minutes and remained significantly lower (P <.05) than resting values until 10 minutes after drug administration, whereas end-systolic volume was unchanged. In group 2, nifedipine induced a minor decrease in end-diastolic volume and a slight but not significant decrease in ejection fraction and end-systolic volume. During the walk test, nifedipine induced similar changes in all parameters of cardiac performance in both groups.

CONCLUSIONS

In patients with impaired LV function, acute nifedipine administration has a negative effect on cardiac performance, which occurs before blood pressure reduction. On the other hand, during moderate physical activity, nifedipine does not affect the improvement in LV function.

Evaluation of the Method for Nifedipine Administration for a Rapid Onset of Clinical Effect: A Clinical Study in Normal Volunteers

Nifedipine is frequently used for patients who require an immediate reduction of blood pressure elevated temporarily by various administration techniques including sublingual route without administrating intravenous infusion of vasodilator. A cross-over clinical study was conducted to investigate the optimal administration method of nifedipine for rapid management of hypertension. Four method of administering 10 mg nifedipine (the capsule was bitten and swallowed, sublingually with a hole in it or the contents administered orally or intranasally with a syringe) were evaluated with regarded efficacy, safety, and usefulness in 6 normal volunteers. Systolic and diastolic blood pressures were correlated with the nifedipine serum concentration in each method. Nifedipine pharmacokinetic parameters differed among the 4 administration methods. Nifedipine was absorbed rapidly by not only intestinal mucosa but also the nasal or oral mucosa. The pharmacological effect of intranasal or sublingual administration was superior. However, mint oil which is present in nifedipine capsules stimulates nasal mucosa when administered intranasally. For clinical usage, nifedipine capsules in which a hole is made with a needle, administered sublingually, can be effectively and safely used for rapid management of systemic hypertension.

Management of acute severe hypertension and encephalopathy

We still do not have an ideal drug to treat acute severe hypertension in pregnancy. Hydralazine and labetalol are the safest agents, but they are inadequate to control blood pressure in some women. Both hypertensive encephalopathy and eclampsia now appear to be forms of an acute process known as reversible posterior leukoencephalopathy syndrome.

Sublingual nifedipine in elderly patients: even a low dose induces myocardial ischaemia

1. Low doses of sublingual nifedipine are still used for the treatment of hypertensive crises, although recent studies have raised concerns that sublingual nifedipine may cause serious dose-dependent adverse effects. The present study was performed to test the safety of low-dose sublingual nifedipine administered to elderly hypertensive patients. 2. Systemic blood pressure measurements and electrocardiographic (ECG) examinations were performed before and 45-60 min after a 5 mg dose of sublingual nifedipine in 93 consecutive hypertensive patients, 65 years of age or older, who were without coronary artery disease. In 33 patients, the effects of nifedipine on myocardial lactate metabolism were studied during cardiac catheterization. 3. In all patients, following nifedipine administration, blood pressure (BP) decreased significantly, while heart rate (HR) increased, and symptoms associated with elevated BP disappeared. However, changes consistent with myocardial ischaemia appeared on the ECG in six of 55 patients with left ventricular hypertrophy (LVH) and in one of 38 patients without LVH, although only two of these seven patients experienced angina-like precordial tightness. Sublingual nifedipine decreased myocardial lactate extraction from 52 +/- 13 to 38 +/- 19% in 20 patients with LVH (P = 0.02), but myocardial lactate extraction remained stable in 13 patients without LVH (49 +/- 7 to 50 +/- 5%; NS). The change in lactate extraction was significantly correlated with the percentage change in diastolic arterial pressure (r = 0.77, P < 0.001). 4. These results suggest that sublingual nifedipine, even at the low dose of 5 mg, may cause myocardial ischaemia in some elderly patients with LVH that is associated with a marked reduction in coronary perfusion pressure.

Asymptomatic hypertension in the ED

A retrospective study in an urban, municipal, teaching hospital emergency department (ED) was conducted to evaluate (1) the frequency of asymptomatic hypertension in the ED, (2) the initial assessment and patterns of treatment by physicians, and (3) the changes in blood pressure (BP) in these patients. Patients with systolic BP > or = 180 mm Hg or diastolic BP > or = 110 mm Hg were included. Patients with cardiovascular, renal, or central nervous system dysfunction were excluded. Of the 11,531 charts reviewed, 269 (2.3%) met inclusion criteria. Of the 269 patients, 56 patients (20.8%) received antihypertensive treatment in the ED. The treatment group had a higher systolic BP (P < .001), diastolic BP (P < .001), and mean arterial blood pressure (MAP) (P < .001) than the nontreatment group. Fundoscopy was also performed more frequently in the treatment group (30.2% v 8.9%, P < .001). MAP decreased for both groups in the ED, but was higher in the treatment group (-20+/-21 v -11+/-21 mm Hg, P=.02). Despite the lack of support in the literature for the emergency treatment of asymptomatic hypertension in the ED, the individual physician's decision for treatment correlated with the degree of hypertension. Significantly elevated BP readings in the ED tended to decrease over time independent of any antihypertensive treatment, although the decrease was larger in the treated patients.

Clinical pharmacokinetics of vasodilators. Part I

Understanding the mechanism of action and the pharmacokinetic properties of vasodilatory drugs facilitates optimal use in clinical practice. It should be kept in mind that a drug belongs to a class but is a distinct entity, sometimes derived from a prototype to achieve a specific effect. The most common pharmacokinetic drug improvement is the development of a drug with a half-life sufficiently long to allow an adequate once-daily dosage. Developing a controlled release preparation can increase the apparent half-life of a drug. Altering the molecular structure may also increase the half-life of a prototype drug. Another desirable improvement is increasing the specificity of a drug, which may result in fewer adverse effects, or more efficacy at the target site. This is especially important for vasodilatory drugs which may be administered over decades for the treatment of hypertension, which usually does not interfere with subjective well-being. Compliance is greatly increased with once-daily dosing. Vasodilatory agents cause relaxation by either a decrease in cytoplasmic calcium, an increase in nitric oxide (NO) or by inhibiting myosin light chain kinase. They are divided into 9 classes: calcium antagonists, potassium channel openers, ACE inhibitors, angiotensin-II receptor antagonists, alpha-adrenergic and imidazole receptor antagonists, beta 1-adrenergic agonist, phosphodiesterase inhibitors, eicosanoids and NO donors. Despite chemical differences, the pharmacokinetic properties of calcium antagonists are similar. Absorption from the gastrointestinal tract is high, with all substances undergoing considerable first-pass metabolism by the liver, resulting in low bioavailability and pronounced individual variation in pharmacokinetics. Renal impairment has little effect on pharmacokinetics since renal elimination of these agents is minimal. Except for the newer drugs of the dihydropyridine type, amlodipine, felodipine, isradipine, nilvadipine, nisoldipine and nitrendipine, the half-life of calcium antagonists is short. Maintaining an effective drug concentration for the remainder of these agents requires multiple daily dosing, in some cases even with controlled release formulations. However, a coat-core preparation of nifedipine has been developed to allow once-daily administration. Adverse effects are directly correlated to the potency of the individual calcium antagonists. Treatment with the potassium channel opener minoxidil is reserved for patients with moderately severe to severe hypertension which is refractory to other treatment. Diazoxide and hydralazine are chiefly used to treat severe hypertensive emergencies, primary pulmonary and malignant hypertension and in severe preeclampsia. ACE inhibitors prevent conversion of angiotensin-I to angiotensin-II and are most effective when renin production is increased. Since ACE is identical to kininase-II, which inactivates the potent endogenous vasodilator bradykinin, ACE inhibition causes a reduction in bradykinin degradation. ACE inhibitors exert cardioprotective and cardioreparative effects by preventing and reversing cardiac fibrosis and ventricular hypertrophy in animal models. The predominant elimination pathway of most ACE inhibitors is via renal excretion. Therefore, renal impairment is associated with reduced elimination and a dosage reduction of 25 to 50% is recommended in patients with moderate to severe renal impairment. Separating angiotensin-II inhibition from bradykinin potentiation has been the goal in developing angiotensin-II receptor antagonists. The incidence of adverse effects of such an agent, losartan, is comparable to that encountered with placebo treatment, and the troublesome cough associated with ACE inhibitors is absent.

Controlling the hemodynamic response to laryngoscopy and endotracheal intubation

The hemodynamic response to the stress of laryngoscopy and endotracheal intubation does not present a problem for most patients. However, patients with cardiovascular or cerebral disease may be at increased risk of morbidity and mortality from the tachycardia and hypertension resulting from this stress. These hemodynamic effects gained notice after the introduction and use of muscle relaxants, such as curare and succinylcholine, for endotracheal intubation at the time of anesthesia induction. A variety of anesthetic techniques and drugs are available to control the hemodynamic response to laryngoscopy and intubation. The method or drug of choice depends on many factors, including the urgency and length of surgery, choice of anesthetic technique, route of administration, medical condition of the patient, and individual preference. The possible solutions number as many as the medications and techniques available and depend on the individual patient and anesthesia care provider. This paper reviews these medications and techniques to guide the clinician in choosing the best methods.

Arterial hemodynamics in human hypertension. Effects of the calcium channel antagonist nifedipine

Previous studies have shown some distinct hemodynamic alterations in essential hypertension, including increased resistance, wave reflections, and pulse wave velocity and decreased arterial compliance. These abnormalities are completely normalized by nonspecific smooth muscle dilation with nitroprusside but not by combined alpha- and beta-adrenergic blockade or angiotensin-converting enzyme inhibition, suggesting an enhanced smooth muscle tone that cannot be attributed solely to the sympathetic nervous or renin-angiotensin systems. Since hypertensive patients have an enhanced calcium influx-dependent vasoconstriction, we performed the present study to examine the extent to which the dihydropyridine calcium channel antagonist nifedipine could normalize the hemodynamic abnormalities in essential hypertension. An essential hypertensive patient group was compared with a normotensive group similar in age, body size, and proportion of men and women. During diagnostic cardiac catheterization, ascending aortic micromanometer pressures and electromagnetic flows were measured at baseline and after sufficient sublingual nifedipine (mean, 24 mg) to normalize blood pressure. From the pressures and flows, aortic input impedance, wave reflection magnitude, and compliance were computed. In the hypertensive group, the hemodynamic alterations were indistinguishable from those summarized above. Nifedipine produced sufficient vasodilation to completely normalize all of these hemodynamic alterations, including wave reflections. From these results, together with those reported in our previous studies, it is clear that the various classes of antihypertensive agents affect hemodynamics differently. All are capable of decreasing blood pressure to normotensive levels, but only nitroprusside and nifedipine can also completely normalize all the other pulsatile hemodynamic alterations. Thus, these hemodynamic effects of the different classes of antihypertensive agents should be considered in choosing a therapeutic modality.

Invasive hemodynamic evaluation of sublingual captopril and nifedipine in patients with arterial hypertension after abdominal aortic surgery

OBJECTIVES

To examine the central hemodynamic and blood gas responses to sublingual captopril and nifedipine administration in patients with arterial hypertension after abdominal aortic surgery.

DESIGN

Prospective, randomized, parallel-group clinical study.

SETTING

Twenty-nine-bed medical-surgical intensive care unit in a university hospital.

PATIENTS

Twenty patients with arterial hypertension (mean arterial pressure of > or = 115 mm Hg) the day after abdominal aortic surgery. Patients with bilateral renal artery stenoses, identified with the preoperative angiogram, were excluded.

INTERVENTIONS

Pressures were measured using intravascular catheters and cardiac output was determined by thermodilution for 2 hrs after captopril 25 mg (n = 10) or nifedipine 10 mg (n = 10) was administered by the sublingual route.

MEASUREMENTS AND MAIN RESULTS

Captopril administration and nifedipine administration decreased mean arterial pressure (from 121 +/- 1 to 94 +/- 4 mm Hg and from 121 +/- 2 to 94 +/- 2 [sem] mm Hg, respectively), pulmonary arterial pressure, pulmonary artery occlusion pressure, and right atrial pressure (p < .001 for all variables). Changes in heart rate and in cardiac output were not significant. PaO2 decreased after nifedipine, from 101 +/- 8 to 81 +/- 3 torr [13.5 +/- 1.1 to 10.8 +/- 0.4 kPa] (p < .01), but not after captopril (104 +/- 9 to 100 +/- 7 torr [13.9 +/- 1.2 to 13.3 +/- 0.9 kPa]). Excessive or symptomatic decreases in blood pressure were not observed, nor was deterioration in renal function observed.

CONCLUSIONS

Sublingual captopril and nifedipine were equally effective for the treatment of arterial hypertension after abdominal aortic surgery. Nifedipine, but not captopril, caused a deterioration in pulmonary gas exchange.

A new preparation of nifedipine for sublingual application in hypertensive urgencies

A new preparation of nifedipine for sublingual application in hypertensive urgencies was investigated in a prospective study. Patients admitted to the Emergency Department with a persistent elevation of systolic blood pressure (SBP) greater than 190 mmHg and/or a diastolic blood pressure (DBP) greater than 100 mmHg received nifedipine 10 mg sublingual with a sprayer. A second dose was administrated fifteen minutes later if an adequate response defined as a stable reduction of SBP below 180 mmHg and DBP below 100 mmHg had not occurred. Of 30 patients, 21 (70%) responded to the first nifedipine application, 7 responded to the second dose, and 2 nonresponders had to be treated with urapidil. Overall mean SBP was 206 +/- 19 mmHg and mean DBP was 113 +/- 15 mmHg before treatment, and a significant antihypertensive effect was noted within fifteen minutes after nifedipine spray (p < 0.05). The maximum antihypertensive effect was for SBP in sixty minutes (146 +/- 19 mmHg) and for DBP after one hundred twenty minutes (78 +/- 18 mmHg). The average reduction in SBP was 29% and in DBP 31%. In first-dose responders (n = 21) a significant antihypertensive effect was noted within fifteen minutes. SBP declined from 205 +/- 21 to a minimum of 142 +/- 15 mmHg (22.3%) after sixty minutes and DBP from 113 +/- 13 to a minimum of 77 +/- 11 mmHg (22.2%) after one hundred twenty minutes. In second-dose responders (n = 7) a significant antihypertensive effect was noted within thirty minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Intranasal delivery of cardiovascular agents: an innovative approach to cardiovascular pharmacotherapy

The intranasal administration of drugs has long been used for the topical treatment of various nasal disorders. Many features of the intranasal mucosa also make it useful for delivery of systemically active agents. It has been shown that intranasal drug administration can provide plasma drug levels similar to those observed with comparable doses of parenteral drugs. The feasibility of intranasal administration of propranolol, nifedipine, and nitroglycerin has been investigated in several small clinical studies. Intranasal propranolol has been shown to improve exercise tolerance in patients with angina pectoris. Intranasal nifedipine has been used to treat patients with perioperative hypertension and hypertensive crisis. Intranasal administration of nitroglycerin was shown to blunt the hypertensive response to endotracheal intubation. These studies and others suggest that intranasal delivery of cardiovascular drug treatment could be used in those clinical situations where a rapid or intermittent drug effect is desired and can potentially serve as an alternative to parenteral drug administration.

Advances in pharmacotherapy: treatment of hypertensive crisis

A hypertensive crisis can be caused by many factors. Frequently, the mechanism involved is complex and highly variable among patients. Without drug therapy, this condition is associated with very high mortality and morbidity. There are a number of oral and intravenous hypotensive agents available, which can effectively control blood pressure in a hypertensive crisis. The relative advantages and disadvantages of each treatment option is discussed.

Oral antihypertensives for hypertensive urgencies

OBJECTIVE

To review the data describing the use of oral antihypertensive agents in the treatment of hypertensive urgencies (HU).

DATA SOURCES

A MEDLINE search of the English-language literature and fan searches of papers evaluating oral antihypertensives in HUs and emergencies were conducted.

STUDY SELECTION

Controlled and uncontrolled studies in humans are reviewed. Emphasis was placed on recent trials evaluating individual agents and comparative trials.

DATA SYNTHESIS

Comparative trials have demonstrated that four currently available oral agents can lower blood pressure rapidly and predictably. Nifedipine, the most extensively studied, and clonidine have served traditionally as the oral agents of choice for the treatment of HUs. All the agents can lower blood pressure effectively within the first few hours after dosing, but their use also has been associated with adverse effects. Nifedipine and captopril are the two agents with the most rapid onset, within 0.5-1 hour, and may treat hypertensive emergencies as well as urgencies. Clonidine and labetalol have maximal blood pressure lowering effects at 2-4 hours.

CONCLUSIONS

Captopril, clonidine, labetalol, and nifedipine are all effective agents for the treatment of HUs. Agent selection should be based on the perceived need for urgent blood pressure control, the cause of HU, and concomitant conditions. A definite benefit from acute blood pressure lowering in HUs has yet to be demonstrated, especially in asymptomatic patients. More controlled trials with less aggressive dosing regimens and placebo controls need to be performed to assess the most appropriate treatment for HUs with the fewest adverse effects.

Oral labetalol versus oral nifedipine in hypertensive urgencies in the ED

Therapy in hypertensive urgencies is debated and complicated by the side effects of available agents. In a prospective, randomized, open labeled study, the use of oral labetalol, an alpha- and beta-adrenergic blocker, with oral nifedipine in hypertensive urgencies in the emergency department was compared. Patients with diastolic blood pressures (DBP) of more than 120 mm Hg without criteria for a hypertensive emergency were eligible. The drugs were given in a loading manner with doses and timing based on their respective pharmacokinetics until a DBP of 110 mm Hg or lower was obtained or 4 hours had passed. Either an initial labetalol dose of 200 mg and a repeat dose of 100 to 200 mg at 2 hours, depending on the DBP or nifedipine, 10-mg bite and swallow every hour up to a total dose of 20 mg were given. Ten patients were enrolled into each study group. A 100% response rate was defined as a DBP of 110 mm Hg or less was observed for nifedipine and an 80% response rate for labetalol (P > .2) was observed. The mean time to control was 67.5 minutes for labetalol and 60.0 minutes for nifedipine (P > .2). The pretreatment pressure for labetalol was 195/127 mm Hg and for nifedipine was 198/128 mm Hg (P > .2), which decreased to a posttreatment pressure for labetalol of 154/100 mm Hg and for nifedipine of 163/100 mm Hg (P > .2). The mean decrease in systolic (SBP)/DBP was 42.6/26.5 mm Hg with labetalol and 34.9/28.4 mm Hg for nifedipine (P > .2). No significant side effects occurred with either drug.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of the acute hypotensive effects of two different doses of nifedipine

To determine whether a dose of 5 mg of nifedipine would be useful in the treatment of hypertensive emergencies, we compared the acute hypotensive effects of two different doses of nifedipine, 5 mg and 10 mg, in patients with severe hypertension. In this prospective, randomized, double-blind study, 30 consecutive black patients with diastolic blood pressure that was equal to or greater than 115 mm Hg received either a 5 mg or 10 mg nifedipine capsule and a placebo capsule, which matched that of the alternative strength. Patients were asked to bite the capsules and swallow the contents. Blood pressure response over 4 hours and adverse effects were monitored. Mean systolic blood pressure was reduced from 191.7 mm Hg (95% confidence interval 170.8 to 212.7 mm Hg) to 157.9 mm Hg (137.0 to 178.9 mm Hg) and 206.1 mm Hg (185.1 to 227.0 mm Hg) to 153.7 mm Hg (132.8 to 174.7 mm Hg) in patients who were given 5 mg and 10 mg doses of nifedipine, respectively. Mean diastolic blood pressure in the group of patients that received 5 mg doses of nifedipine decreased from 128.2 mm Hg (115.6 to 140.7 mm Hg) to 105.2 mm Hg (92.7 to 117.7 mm Hg); the corresponding values in the group that received 10 mg doses of nifedipine were 129.9 mm Hg (117.4 to 142.5 mm Hg) and 97.5 mm Hg (85.0 to 110.1 mm Hg), respectively. The minimum mean systolic blood pressures occurred 20 and 25 minutes after administration of the 5 mg and 10 mg capsules, respectively; the minimum diastolic blood pressures were reached after 20 and 30 minutes, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Is sublingual nifedipine administration superior to oral administration in the active treatment of hypertension?

Nifedipine, a calcium-channel-blocking agent, was administered orally to 44 untreated patients (Group A) and sublingually to 51 untreated patients (Group B) who had a diastolic blood pressure more than 90 mm Hg and systolic blood pressure more than 140 mm Hg. The mean pretreatment systolic and diastolic blood pressure values were 185.3 +/- 26.0 and 115.1 +/- 13.4 mm Hg in Group A patients and 193.6 +/- 23.1 and 118.1 +/- 14.1 mm Hg in Group B patients respectively (p greater than 0.05). The hypotensive activity of nifedipine was observed at the tenth minute in both groups. Mean systolic and diastolic pressures were 168.9 +/- 23.7 and 101.9 +/- 14.2 mm Hg in Group A and 170.6 +/- 26.2 and 103.0 +/- 15.8 mm Hg in Group B, (p less than 0.001) Diastolic blood pressures dropped under 100 mm Hg at the twentieth minute in both groups. Maximal reduction of blood pressure was observed at the fortieth minute in both groups and the degree of reduction in blood pressure was also the same (mean systolic and diastolic blood pressures: 143.7 +/- 22.1 and 86.9 +/- 11.7 in Group A and 148.7 +/- 21.4 and 91.7 +/- 17.0 in Group B (p less than 0.05). The authors conclude that sublingual nifedipine administration is not superior to oral nifedipine administration (in capsular form) in the acute treatment of hypertension.

Oral nifedipine in the treatment of hypertensive crises in patients with hypertensive encephalopathy

Hypertensive emergencies, including hypertensive encephalopathy represents an acute threat to vital organ functions and call for urgent treatment. The intravenous medications currently available for the management of hypertensive emergencies, have significant potential for serious side effects and acute lowering of blood pressure has often been the cause of considerable morbidity and mortality. Nifedipine is known to be effective as an antihypertensive agent and it is widely used in hypertensive emergencies. We studied the efficacy and effective dose of nifedipine in 22 patients (9 females and 13 males; mean age 51) with hypertensive encephalopathy. Nifedipine (20 mg by oral drop) caused a significant fall in diastolic an systolic blood pressure in all patients from 236/121 to 172/96 mmHg after 30 minutes (P less than 0.005, P less than 0.001). Continuous therapy with nifedipine (2-5 mg every 2-3 hours, mean total dose 52 mg/24 h) gave successful control of blood pressure. These data prove that nifedipine can be used as the first-line drug for the treatment of hypertensive crises in patients with hypertensive encephalopathy.

Management of hypertensive emergencies: changing therapeutic options

Rapid lowering of severe hypertension is essential to prevent irreversible damage to vital organs. The patient's clinical status should be evaluated, noting particularly cardiac, neurologic, and renal functions. Choice of treatment should be based on speed and efficacy of action and on hemodynamic, vascular, and renal consequences. It is also important to preserve circulatory homeostasis and vital organ function. Sodium nitroprusside, labetalol, diazoxide, and hydralazine have been used parenterally for rapid control of severe hypertension, but they do not always produce optimal, balanced hemodynamic effects. Calcium antagonists have been advocated because of their beneficial circulatory effects. Nicardipine, a new dihydropyridine calcium antagonist, produces significant antihypertensive effects, and when given intravenously, results in a rapid fall in blood pressure. Studies have confirmed that nicardipine is effective and safe in the management of severe hypertension and hypertensive crises. Because the aim of rapidly controlling severe hypertension is to prevent target organ dysfunction, nicardipine therapy offers a useful additional option in the clinical management of severe hypertension and hypertensive crises.

Dose-response evaluation of oral labetalol in patients presenting to the emergency department with accelerated hypertension

STUDY OBJECTIVE

Dose-response evaluation of oral labetalol (100, 200, or 300 mg) on heart rate and systemic blood pressure in emergency department patients with hypertensive urgency (diastolic blood pressure, 110 to 140 mm Hg, and no end-organ evidence of hypertensive emergency).

METHODS

This acute-treatment, dose-ranging study used a randomized, double-blind, parallel design. Patients with supine diastolic blood pressure of 110 to 140 mm Hg after 30 minutes of bedrest received an oral dose of labetalol. Supine blood pressure and heart rate were measured manually and recorded hourly for four hours after dose. Diastolic blood pressure of 100 mm Hg or less or a 30-mm Hg reduction in diastolic blood pressure was considered a treatment success.

RESULTS

Two hundred fifty-five patients were evaluated for inclusion, and 36 patients (19 women and 17 men; mean age, 44 years; age range, 23 to 67 years) were studied. The most frequent reason for exclusion was a spontaneous decrease in diastolic blood pressure to less than 110 mm Hg (31%) with bedrest. There were 12 patients in each treatment group. Compared with baseline, the 100-mg dose significantly (P less than .05) reduced heart rate at three and four hours after dose, and the 300-mg dose significantly (P less than .05) reduced heart rate at one, two, and three hours after dose; the 200-mg dose did not significantly affect heart rate. All doses produced a significant decrease in systolic and diastolic blood pressures at one, two, three, and four hours after dose compared with baseline. There were no statistically significant differences between treatment groups with regard to systolic or diastolic blood pressure or heart rate at baseline or one, two, three, or four hours after dose. At two hours after dose, diastolic blood pressure control was observed in 75%, 58%, and 67% of patients receiving 100, 200, and 300 mg, respectively (P = .903). At four hours after dose, diastolic blood pressure control was observed in 50%, 64%, and 67% of patients receiving 100, 200, and 300 mg, respectively (P = .755). A comparison of treatment success rates between the two time periods showed a waning of response with the 100-mg dose of labetalol at hour 4 compared with hour 2 (P less than .05). No adverse effects were observed.

CONCLUSION

Labetalol provides safe and effective treatment for hypertensive urgencies when administered orally in doses of 100 to 300 mg.

Oral labetalol in hypertensive urgencies

The response to incremental doses of oral labetalol in 16 patients with hypertensive urgencies is presented. After inadequate blood pressure control with 20 mg of intravenous furosemide, each patient received a 300 mg oral dose of labetalol. Subsequent oral doses of labetalol, 100 mg, were administered at 2-hour intervals, if the diastolic blood pressure remained greater than 100 mm Hg. The maximum dose of labetalol per patient was 500 mg. Five patients required only the initial 300 mg dose of labetalol. Two patients required further therapy for satisfactory blood pressure control. Mean arterial pressure fell from 156 +/- 12 mm Hg to 123 +/- 14 mm Hg.

Pharmacokinetics of nifedipine derived from a new retard tablet formulation

A nifedipine retard tablet formation (Glopir, 20mg) was developed to reduce the number of daily doses required in the treatment of hypertension. The plasma pharmacokinetics of this oral formulation were examined, in a single study, on 12 healthy volunteers. Single 20 mg doses of nifedipine retard tablet (Glopir, GAP & Co. Athens, Greece) were given after an overnight fast and 10 blood samples were drawn during the first 24 h after administration. Plasma concentrations of nifedipine were measured by high performance liquid chromatography. The mean peak plasma nifedipine concentration was 27.6 ng/ml at a maximum time of 24 h, after tablet ingestion. The mean apparent nifedipine elimination half-life was 16.0 +/- 7.5 h and the mean area under the plasma concentration time curve (0-24 h) 404.1 +/- 134.0 ng/ml.h. The data suggest that the tablet form has properties of a sustained-release preparation, with slow accumulation and elimination phases and can appropriately be given in a twice-daily regimen.

Prehospital use of nifedipine for severe hypertension

The prehospital management of severe hypertension is limited by a paucity of pharmacologic agents suitable for field use. This prospective study was designed to test the safety and efficacy of intraoral nifedipine therapy in 50 patients with severe hypertension being transported by an urban emergency medical service system. Ten milligrams of nifedipine were administered. Serial blood pressure determinations were obtained at 3, 5, 10, and 15 minutes and patients were observed for possible side effects. A marked effect on systolic blood pressure (SP), diastolic blood pressure (DP), and mean arterial pressure (MAP) was evident and was statistically significant in all three categories by 3 minutes. MAP decreased from 169 to 129 mm Hg (delta MAP of 40 mm Hg) at 15 minutes with parallel changes in the SP (55 mm Hg) and delta DP (32 mm Hg). These changes were highly significant (P less than .01) when compared with those of 50 historical controls. No evidence of severe adverse effects were noted. Nifedipine appears to be a promising agent for the prehospital treatment of severe hypertension, but its proper role is not yet defined.

Nifedipine in the treatment of hypertensive episodes in the coronary care unit

The effectiveness of nifedipine for the treatment of acute hypertensive episodes in patients already taking chronic calcium-channel blocker therapy is unknown. We report our experience with 43 consecutive patients who received nifedipine for acute hypertensive episodes in the coronary care unit. Of the 43 patients (24 men, 19 women), 23 (53 percent) were taking chronic (greater than 2 mo) calcium-channel blocker therapy. Nifedipine 10 mg capsules were chewed and swallowed with repeat doses given at hourly intervals if necessary. Target BP was 140/90 mm Hg, which was achieved in 31 of 43 patients (72 percent). In patients already taking calcium-channel blockers, target BP was achieved in 18 of 23 patients (78 percent). Response in patients not taking chronic calcium-channel blockers was observed in 13 of 20 patients (65 percent). Overall, adverse effects occurred in 16 of 43 patients (37 percent): 11 of 23 patients (48 percent) taking calcium-channel blockers, and 5 of 20 patients (25 percent) not taking calcium-channel blockers. Nifedipine is equally effective in lowering BP in patients taking calcium-channel blockers as it is in patients not taking them. Although associated with a higher incidence of adverse effects in patients already taking calcium-channel blockers, these effects were not considered serious. Nifedipine is an effective agent in acute hypertensive episodes, even in patients receiving chronic calcium-channel blocker therapy.

A comparison of sublingual nifedipine versus nitroglycerin in the treatment of acute angina pectoris

The administration of nifedipine by the sublingual rather than the oral route has been suggested to provide a more rapid onset of effect. We compared the safety and efficacy of sl nifedipine to sl nitroglycerin in patients who developed anginal chest pain during diagnostic exercise stress testing. Consecutive patients undergoing diagnostic Bruce treadmill exercise who had not had a recent myocardial infarction or undergone coronary bypass graft surgery and who were not taking nitrates, beta-blockers, digoxin, or calcium antagonists were eligible. Seventy-eight patients meeting the inclusion/exclusion criteria consented to participate. Of these 78, 13 developed chest pain necessitating exercise cessation and were randomized to either nitroglycerin or nifedipine. Nitroglycerin was initially given to seven patients and nifedipine to six patients. Complete pain relief was observed in five of seven (71 percent) nitroglycerin patients at two minutes postdose. At four minutes postdose, the remaining two nitroglycerin patients were essentially pain-free. At two minutes postdose, no patient receiving nifedipine had complete pain resolution, and only one patient (17 percent) had partial (greater than 50 percent) pain relief. At four minutes postdose, four of the nifedipine patients were crossed over to nitroglycerin. At two minutes after the nitroglycerin dose, all four patients had total pain relief. The remaining two nifedipine patients had partial pain relief and were not crossed over to nitroglycerin. Subjective side effects and changes in heart rate and blood pressure were not significantly different between nitroglycerin and nifedipine.(ABSTRACT TRUNCATED AT 250 WORDS)

Nifedipine attenuates the intraocular pressure response to intubation following succinylcholine

Forty patients without eye disease, undergoing elective nonophthalmic surgery, were studied to evaluate the efficacy of sublingual nifedipine in attenuating the intraocular pressure response to succinylcholine administration, laryngoscopy and intubation. The patients were randomly given either nifedipine 10 mg or placebo sublingually 20 minutes before induction of anaesthesia. Intraocular pressure (IOP) and systolic blood pressure (SBP) were recorded before and after induction of anaesthesia. The IOP response to succinylcholine administration, laryngoscopy and intubation was significantly less in patients receiving nifedipine (P less than 0.01). The mean maximum rise in IOP above basal level at one minute post-intubation was 7.82 mmHg in the control group compared with 0.15 mmHg in the nifedipine pre-treated group. These results suggest that sublingual nifedipine is effective in attenuating the IOP response after succinylcholine administration, laryngoscopy and intubation.

Subcutaneous administration of nifedipine

Contents of a 10 mg nifedipine capsule (0.33 ml) were withdrawn by syringe and administered subcutaneously to a patient with hypertensive urgency due to misinterpretation of a physician's order. The drug apparently had its desired hypotensive effect and no adverse effects were noted. The literature on use of nifedipine in hypertensive urgency is reviewed. Subcutaneous administration is not recommended because of a lack of suitable controlled studies and the potential for adverse effects.

Calcium antagonists, a new class of antihypertensive agents

The mechanism of action of Ca++ antagonists remains debatable. Not all voltage-sensitive calcium channels have the same sensitivity to organic calcium blockers. Those in smooth muscle are clearly more sensitive than those in heart, and at least some of those in brain are not blocked at all. It is possible that in vascular smooth muscle, calcium antagonists act essentially on receptor-operated channels. In any case, calcium antagonists are potent antihypertensive agents, but in clinical practice they have limitations. A second generation of dihydropyridines may provide a higher degree of therapeutic selectivity.

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)

Calcium antagonists and their potential for antihypertensive therapy

Calcium antagonists are potent arterial vasodilators devoid of relevant chronic sympathetic reflex activation and sodium and volume retention. This favorable hemodynamic profile of action renders them suitable for monotherapy of hypertension where they act to reduce an enhanced, calcium-influx-dependent vasoconstrictor mechanism which may be brought about by altered smooth muscle cation handling and increased intracellular free calcium concentrations. Clinical studies have proved their efficacy, safety, and good tolerability alone or in combination with other drugs in uncomplicated hypertension where they are particularly effective in older and low-renin and possibly black patients. These properties and their efficacy in the treatment of severe and accelerated hypertension or hypertensive emergencies make them a valuable addition to already available drug therapy.

Drug treatment of hypertension

There are several first choices for the treatment of mild and moderate hypertension. The selection of a drug may be influenced by concomitant pathology, with positive indications for particular drugs, e.g. coexistent angina, indicating use of a beta-receptor blocking drug or calcium antagonist; fluid retention indicating a diuretic; or contraindication e.g. asthma, and beta-adrenoceptor blocking drugs. beta-Adrenoceptor blocking drugs have the advantage of a long history and of possibly being cardioprotective following myocardial infarction, but they have not yet been established as primary preventive agents in hypertensive patients. The alpha-receptor blocking drugs have the advantage of favourably affecting lipid profile and blood pressure. Therefore, there may be advantages in the use of combined alpha- and beta-blockade. The diuretics, which have the advantage of being inexpensive, are widely used but long term metabolic effects, particularly hypokalaemia, cause concern. This is correctable by co-administration of a potassium sparing diuretic and often preventable by using low doses of the diuretic. Diet may be important as hypokalaemia appears to be less of a problem where potassium intake is high. Experience with calcium antagonists is widening but the use of converting enzyme inhibitors is more limited, and some physicians are less ready to use them as first choice in mild hypertension at present. Drugs like methyldopa, clonidine, the adrenergic neurone inhibitory drugs are now used more as reserve agents. More severe cases of hypertension may require drugs from 2 of the 3 major groups: beta-blocking drugs, vasodilators and diuretics. In some cases, drugs from each of these 3 groups will be required.

Blood pressure effects of monoamine oxidase inhibitors--the highs and lows

Clinical guidelines for the management of the most common side effects associated with monoamine oxidase inhibitors (postural hypotension and hypertensive episodes) are offered. When non-pharmacological interventions fail to alleviate MAOI induced postural hypotension, the use of volume expanders (salt tablets or fludrocortisone) may be effective alternatives to drug discontinuation. Phentolamine and chlorpromazine are traditional drug treatments for MAOI hypertensive emergencies. The newer drug treatments evolved in the last decade for treating hypertensive emergencies is not reflected in the psychiatric or emergency medicine literature on treating MAOI induced hypertensive states. Nifedipine, diazoxide, or sodium nitroprusside appear to be more rational choices for this problem.

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.

The effect of nifedipine on cystoscopy-induced autonomic hyperreflexia in patients with high spinal cord injuries

We evaluated the ability of the calcium channel blocker nifedipine to control autonomic hyperreflexia during cystoscopy in 7 patients with cervical spinal cord injuries. Nifedipine (10 mg.) alleviated autonomic hyperreflexia when given sublingually during cystoscopy and prevented autonomic hyperreflexia when given orally 30 minutes before cystoscopy. No adverse drug effects were observed.

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.