Antihypertensive efficacy of lisinopril. Ambulatory blood pressure monitoring

Computation of model-dependent tolerance bands for ambulatorily monitored blood pressure

The construction of time-specified reference limits requires systematic sampling in clinical health, particularly for those variables characterized by a circadian rhythm of large amplitude, as it is the case for blood pressure (BP). For the detection of false negatives, tolerance intervals (limits that will include at least a specified proportion of the population with a stated confidence) are important and should substitute when possible for prediction limits. We have previously described a nonparametric method for the computation of model-independent tolerance intervals that are constructed by first dividing the sampling range in several time spans in which no appreciable changes in population characteristics (namely, mean and variance) take place. The tolerance interval is then computed for each of the time spans. The limits thus computed, as well as results of any comparison of a given individual's profile against such tolerance intervals, are highly dependent on the sampling scheme of both the reference individuals and the test subject. To avoid this problem, we have developed an alternative method that allows the computation of model-dependent tolerance bands for hybrid time series. Assuming that a set X of longitudinal series monitored from a given group of reference individuals can be fitted with the same individual model, a population model C(X,t) can be also determined, as well as the deviation S(X,t) of each individual curve from the population model. The tolerance band will then have the form C(X,t) +/- kS(X,t), where k is here estimated following a nonparametric approach based on bootstrap techniques. Alternatively, two different values of k can be estimated (for the lower and upper limits of the tolerance interval, respectively) in cases for which we cannot assume symmetry. The method is generally applicable for any population model describing the reference population (including the fit of multiple significant components, nonsinusoidal waveforms, and/or trends). The method was used to establish time-specified tolerance bands for time series of blood pressure monitored automatically in healthy individuals of both genders. Model-dependent intervals are preferred to the model-independent limits when reliance on a specified sampling rate needs to be avoided. These limits may serve for an objective and positive definition of health, for the screening and diagnosis of disease, and for gauging the subject's response to treatment.

Reproducibility of the hyperbaric index as a measure of blood pressure excess

The approach of establishing a time-specified tolerance limit reflecting the circadian variability in blood pressure and then determining the hyperbaric index, the area of blood pressure excess above the upper limit of the tolerance interval, has been proposed for diagnosing hypertension as well as for evaluating the patient's response to treatment. The retrospective evaluation of this test provided high sensitivity and specificity in the diagnosis of hypertension, with a threshold value for the hyperbaric index of 15 mm Hg. h. To evaluate the stability and reproducibility of this tolerance-hyperbaric test, we studied 332 previously untreated subjects (218 men) who underwent sequential 48-hour ambulatory blood pressure monitoring for 2 years, providing a total of 1337 blood pressure profiles. Diagnosis of hypertension was established for each subject on the restricted basis of presenting at least 1 blood pressure profile with a hyperbaric index above the previously defined threshold. Sensitivity of this tolerance-hyperbaric test was 98.6%, with a negative predictive value of 99.7%. For the same subjects, the blood pressure load (percentage of values >140/110/90 mm Hg for systolic/mean arterial/diastolic blood pressure during activity or >120/95/80 mm Hg during resting hours) had a sensitivity of 49% and specificity of 25%. The 24-hour mean, still the most common approach for diagnosing hypertension on the basis of ambulatory monitoring, had sensitivities of 40% and 31% for systolic and diastolic blood pressure, respectively. Despite the limitations of ambulatory blood pressure monitoring, the tolerance-hyperbaric test represents a reproducible, noninvasive, and high-sensitivity test for the identification of subjects in need of prophylactic or therapeutic intervention.

Individual assessment of antihypertensive response by self-starting cumulative sums

A self-interpreted control chart, on an individualized basis, assesses the effect of a switch from beta-blockers to an angiotensin-converting enzyme (ACE)-inhibitor in a patient with occasional blood pressure (BP) excess. In dense and long data series, the BP and heart rate (HR) of this patient respond to the change in treatment by the test criterion of a self-starting Cumulative Sum (cusum), which reaches values outside a decision interval with a lowering of BP and an increase in HR and vice versa, at least for BP, after treatment cessation. Thereafter, minimal sampling requirements are sought in the same data by applying the same control chart approach to decimated data. Skeleton sampling schemes in a system of chronobiologic self-analysis and interpretation of manually recorded data obtained at strategically placed times (established on the basis of data decimations) could complement control charts that are used on a home computer or preferably would be built into the output of ambulatory monitors used at the outset as a minimum and routinely as an optimum.

Conflicting data on intervillous circulation in early pregnancy

According to classic embryological textbooks intervillous circulation is established early in the first trimester. This process starts with trophoblastic invasion of the decidua in which proteolytic enzymes facilitate the penetration and erosion of the adjacent maternal capillaries with formation of the lacunae. After the lacunar or previllous stage trophoblast invades deeper portions of endometrium with belonging spiral arteries. This gradual process finishes with direct opening of the spiral arteries in the intervillous space under the fully developed placenta. This classic concept of establishment of the intervillous circulation was challenged in 1987 and 1988 by the experiments of HUSTIN and SHAAPS. The authors believed that blood flow in the intervillous space is absent in incompletely development before 12 weeks of gestation. After the introduction of the new generation of far more sensitive color Doppler devices in the last few years, our group and several others reported a positive finding of intervillous circulation during the first trimester of pregnancy.

Comparison between enalapril and lisinopril in mild-moderate hypertension: a comprehensive model for evaluation of drug efficacy

The objective of this study was to compare enalapril with lisinopril in terms of blood pressure control at rest, during dynamic exercise test, during isometric exercise test, and during 24 h--with special focus on blood pressure control during the morning hours, 18-24 h post-dose. Furthermore, we compared ACE activity in serum before and after 4 weeks of drug treatment. A four-week double-blind, randomized parallel group study compared enalapril 20 mg o.d. with lisinopril 20 mg o.d. preceded by a 4-week single blind run-in period on placebo. Fifty-eight patients (49 males and 9 females, mean age 50.9) were recruited and 56 completed the study. Blood pressures at randomization were 161/108 and 164/106 for the enalapril and the lisinopril subjects, respectively. Echo: LVPWd 9.5 (normal range 6-12 mm) and IVSd 10.3 mm (normal range 6-12 mm).

STATISTICS

ANCOVA. Enalapril and lisinopril were equally effective in lowering blood pressure at rest, during dynamic and isometric exercise as well as during 24 h. The attained blood pressure levels during the early morning hours were for enalapril treatment 119/76 and 121/76 mmHg for lisinopril treatment. The ACE activity in serum 24 h post-dose was lower (p < 0.001) after treatment with lisinopril 8.0 (SD 3.3) mumol/min/1 than with enalapril 16.1 (SD 6.0). The corresponding values for placebo were 18.8 (SD 4.6) and 17.8 (SD 5.7). No difference was found in blood pressure lowering efficacy between enalapril and lisinopril even though the blood pressure changes were evaluated in a more comprehensive way than in earlier studies of these drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Antihypertensive therapy and circadian blood pressure profiles: a retrospective analysis utilising cumulative sums

The results of previous studies on the effects of antihypertensive agents on circadian blood pressure patterns are inconclusive, possibly due to the lack of a simple, objective, universally accepted method of quantifying circadian blood pressure profiles. In order to investigate for differences in the effects of antihypertensive drugs on circadian changes we utilised a recently described modified cumulative sums technique to quantify circadian alteration magnitude (CAM). CAM is simply calculated as the difference between crest and trough blood pressures, the mean blood pressures of the 6-h periods of highest and lowest sustained pressures respectively. The records from all 24-h ambulatory blood pressure monitoring performed over a 7 year period on subjects either on no medication (1208), or on treatment with a single first-line antihypertensive agent (578), were examined retrospectively. A sample (n = 40) stratified for trough diastolic blood pressure, age and sex was randomly selected from each of the following 5 groups: subjects on no medication, and subjects being treated with bendrofluazide, atenolol, class 2 calcium-channel blockers or captopril alone. Untreated subjects, those on bendrofluazide and those on a class 2 calcium channel blocker had similar circadian patterns. Subjects on atenolol therapy (25.9 +/- 1.7/18.3 +/- 1.3, systolic CAM +/- SE/diastolic CAM +/- SE) had attenuated circadian changes (p < 0.05) when compared to the untreated group (29.8 +/- 1.8/23.6 +/- 1.1), while those on captopril (34.9 +/- 2.4/25.7 +/- 1.8) exhibited markedly increased systolic and diastolic circadian blood pressure swings, which differed from those of the atenolol treated group (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Once-daily trandolapril compared with the twice-daily formulation in the treatment of mild to moderate essential hypertension: assessment by conventional and ambulatory blood pressures

A double-blind, crossover study was carried out to compare the antihypertensive efficacy of the long-acting ACE inhibitor trandolapril 1 mg administered once daily and 0.5 mg twice daily in 31 patients with mild to moderate essential hypertension. After randomization, patients entered a single-blind placebo period of 4 weeks. After a double-blind treatment of 4 weeks with either of the dosage regimens, patients were then crossed over to the alternate regimen for the last 4 weeks of the study. Conventional BP and heart rate were measured on each visit and ambulatory BP monitoring was done at baseline and at the end of each treatment phase. Conventional as well as 24-hour and awake ambulatory systolic and diastolic BPs were significantly (P < 0.001) and almost identically decreased by both once- and twice-daily formulations. Moreover, the clinical response rates (reduction in seated diastolic BP > or = 10% or diastolic BP < or = 90 mm Hg) were similar with both treatment regimens (42% vs. 45% with the once- and twice-daily formulations, respectively). However, trandolapril twice daily exerted a significantly (P = 0.03) greater antihypertensive effect on systolic BP during sleep as compared with the once-daily formulation. Due to the fact that the minimal effective dose was used in this trial, further studies with higher doses should demonstrate effective 24-hour control of BP as described with other long-acting ACE inhibitors. In addition, our results suggest that ambulatory BP measurements should be done in dose-response studies.

Comparison of quinapril and atenolol as single drugs or in combination with hydrochlorothiazide in moderate to severe hypertensives, using automated ambulatory monitoring

1. Forty patients with moderate to severe hypertension and daytime ambulatory diastolic blood pressure > or = 90 mm Hg were randomized double-blind to once-daily treatment with either quinapril up to 20 mg (n = 20) or atenolol up to 100 mg (n = 20) as single drugs or in combination with hydrochlorothiazide 25 mg over a period of 12 weeks. 2. Conventional and ambulatory blood pressure, heart rate, side effects and metabolic changes were compared at the end of the run-in period on placebo, after 4 weeks on monotherapy and at the end of the 12-week period of active treatment. 3. Quinapril and atenolol reduced conventional blood pressure equally with substantial additional effect seen on combination therapy. The two regimens induced a significant decrease in ambulatory BP. However, the atenolol treated ambulatory hypertensive group experienced significantly greater decreases in diastolic blood pressure during 24 h, awake and sleep periods than did the quinapril group. 4. Adverse reactions were mild with both drugs except for severe Raynaud phenomenon in one patient in the atenolol group. Triglyceride levels were significantly increased with atenolol alone and in combination with hydrochlorothiazide. 5. Thus, within the limits of the dose ranges tested, quinapril and atenolol as single drugs or in combination with hydrochlorothiazide reduce significantly conventional and ambulatory blood pressure in moderate to severe hypertensives, but atenolol is more effective in reducing ambulatory diastolic blood pressure.

Trandolapril. How does it differ from other angiotensin converting enzyme inhibitors?

Among the physicochemical, pharmacokinetic and pharmacodynamic properties that differentiate trandolapril from other angiotensin converting enzyme (ACE) inhibitors, the most clinically relevant ones are those that contribute to the long duration of action of the drug. The long elimination half-life of trandolapril and its strong lipophilicity, high ACE inhibitor potency and high affinity for the ACE cause the drug to have a long biological half-life. The long duration of action of trandolapril may be demonstrated experimentally; near total ACE inhibition is observed 24 hours after single dose administration and there is significant ACE inhibition 72 hours following drug withdrawal after long term therapy. We have analysed the duration of blood pressure lowering during long term therapy with commercially available ACE inhibitors in published studies using ambulatory blood pressure monitoring. On the basis of results from 19 studies undertaken in patients with mild to moderate hypertension, it was possible to reconstruct the curve of the magnitude of blood pressure changes against time. Mean trough: peak ratio calculations showed that once-daily administration produced ratios higher than 50% with enalapril (40 to 80%), lisinopril (40 to 70%) and trandolapril (50 to 100%). Other ACE inhibitors had trough: peak ratios lower than 50%. Despite many methodological limitations, this literature analysis demonstrates that trandolapril has a blood pressure-lowering effect for the full 24-hour period. Studies in which a dose is occasionally omitted show that the blood pressure-lowering effect of trandolapril may last beyond 24 hours.

Once-daily lisinopril compared with twice-daily captopril in the treatment of mild to moderate hypertension: assessment of office and ambulatory blood pressures

This multicenter, double-blind, parallel-group study compared the antihypertensive effects of two angiotensin-converting enzyme inhibitors, lisinopril and captopril, in 70 patients (35 lisinopril, 35 captopril) with mild-to-moderate essential hypertension. Doses of 10, 20, and 40 mg once-daily lisinopril or 25, 50, and 100 mg bid captopril were increased at biweekly intervals until patients responded to treatment, as defined by a decrease in office diastolic pressure to less than 90 mm Hg or at least a 10 mm Hg decrease from baseline. Patients who responded to a 2-week titration dose remained at that dose for another 2 weeks. Blood pressure assessments were made using both office and ambulatory blood pressure monitoring. Area under the curve analysis of ambulatory blood pressure reductions showed significant differences between treatment groups for both systolic (P = .023) and diastolic (P = .007) blood pressures, with lisinopril-treated patients showing the most significant reduction in pressure. Greater reductions (P less than .05) were also noted in patients receiving lisinopril at hours 10 to 12, suggesting two blood pressure troughs for those receiving captopril. Both drugs were well tolerated, and no patients withdrew from either treatment group. The authors concluded that after at least 4 weeks of therapy, once-daily lisinopril administration was more effective than twice-daily captopril administration in reducing blood pressure, when measured by 24-hour ambulatory blood pressure monitoring.

Antihypertensive effects of a new sustained-release formulation of nifedipine

The blood pressure response to a new sustained-release formulation of nifedipine was evaluated in an 8-week, double-blind, placebo-controlled study. Twenty-nine patients with mild essential hypertension were randomized to receive placebo (N = 9), 30 mg nifedipine (N = 10), or 60 mg nifedipine (N = 10). During treatment, 30-mg and 60-mg doses of nifedipine administered once daily decreased office blood pressures from 137/98 +/- 8/2 mm Hg and 141/98 +/- 15/2 mm Hg at baseline, respectively, to 126/89 +/- 9/7 mm Hg and 126/86 +/- 6/7 mm Hg (P less than .005). Noninvasive automatic ambulatory blood pressure monitoring demonstrated a marginally significant (P less than .10) reduction in the mean 24-hour blood pressure of 2/6 +/- 8/8 mm Hg and 5/6 +/- 9/9 mm Hg for patients taking 30 mg and 60 mg nifedipine once daily, respectively. Diastolic blood pressure load (the percentage of ambulatory diastolic blood pressure readings greater than 90 mm Hg) during 24 hours was decreased by 41% and 35%, with 30 mg and 60 mg nifedipine administered once daily, respectively. No significant dose response to nifedipine at these dose levels was observed. Although the once-daily formulation of nifedipine achieved effective control of office blood pressure, similar control was not observed in awake and 24-hour periods in all patients.

Clinical use of home and ambulatory blood pressure monitoring

Blood pressure measurements made in the physician's office with a mercury-column sphygmomanometer traditionally have been the standard for diagnosis of hypertension and determination of the efficacy of antihypertensive agents. The utility of this measurement is limited, however, by the characteristic variability of blood pressure; office blood pressure readings are not always reliable indicators of pressures occurring throughout the course of the day. Therefore, blood pressure measurements performed by patients or family members at home and automatic ambulatory blood pressure monitoring are two supplementary methods used in the clinical management of hypertension. In this article, the role of these methods in the diagnosis of hypertension and other cardiovascular disorders as well as in the evaluation of the efficacy of antihypertensive therapy is addressed.