The trough-to-peak ratio as an instrument to evaluate antihypertensive drugs. The APTH Investigators. Ambulatory Blood Pressure and Treatment of Hypertension Trial

Ambulatory blood pressure response to S‐amlodipine in Korean adult patients with uncontrolled essential hypertension: A prospective, observational study

Although amlodipine is recommended as the first‐line therapy for the treatment of hypertension, its use is limited by its potential side effects. S‐amlodipine is expected to be able to minimize side effects of amlodipine with a similar antihypertensive effect by removing the malicious R‐chiral form. However, sustainable blood pressure control with S‐amlodipine has not been well established yet. The purpose of the current study was to evaluate ambulatory blood pressure (ABP) profiles before and after a 12‐week treatment of S‐amlodipine. Patients received once‐daily S‐amlodipine 2.5 or 5 mg. ABP during 24 hr and office blood pressure were measured at baseline and after the 12‐week treatment. Primary endpoints were changes of systolic and diastolic 24 hr ABP. After 12‐week S‐amlodipine treatment, mean systolic ABP (‐15.1 ± 16.2 mmHg, p < .001) and diastolic ABP (‐8.9 ± 9.8 mmHg, p < .001) were decreased significantly. Both daytime and night‐time mean systolic BP and diastolic BP were also significantly decreased after the 12‐week treatment. Global trough‐to‐peak ratio and smoothness index after 12‐week S‐amlodipine treatment were .75 and .79 for SBP and .65 and .61 for DBP, respectively. Age ≥65 years (hazard ratio [HR]: 3.13; 95% confidence interval [CI]: 1.67–14.3) and nonalcohol drinking (HR: 3.09; 95% CI: 1.34–7.17) were independent clinical factors for target ABP achievement. Adverse drug reactions (ADR) were developed in 16 (6.4%) patients, including two (.8%) cases of peripheral edema. In conclusion, this study demonstrated the efficacy and safety of S‐amlodipine in patients with uncontrolled essential hypertension.

24-Hour blood pressure response to lower dose (30 mg) fimasartan in Korean patients with mild to moderate essential hypertension

BACKGROUND/AIMS

Fimasartan is an angiotensin type 1 receptor blocker (ARB) which has comparable efficacy and tolerability with other ARBs. The aim of this study was to evaluate 24-hour blood pressure (BP) lowering efficacy and the tolerability of the low dose fimasartan compared with valsartan in patients with mild to moderate hypertension.

METHODS

This study was a phase II, prospective, multicenter, randomized, double-blind, parallel-grouped trial. A total of 75 hypertensive patients, whose mean ambulatory BP monitoring values were ≥ 135/85 mmHg, were randomized to either fimasartan 30 mg or valsartan 80 mg daily. The primary efficacy endpoint was the change in the mean 24-hour systolic BP (SBP) values from the baseline and at the week 8. Secondary endpoints included the change in the mean 24-hour diastolic BP values, the daytime and the nighttime mean BP values at week 8, the trough-to-peak (T/P) ratio and the smoothness index.

RESULTS

At week 8, the mean 24-hour SBP values significantly decreased in both groups; -10.5 ± 11.9 mmHg (p < 0.0001) in the fimasartan group and -5.5 ± 11.6 mmHg (p = 0.0307) in the valsartan group. The difference between two groups was 4.3 ± 2.9 mmHg but there was no statistical significance (p = 0.1392). The global T/P ratio in the fimasartan 30 mg groups were 0.48 and 0.40 in the valsartan 80 mg group, respectively (p = 0.3411). The most frequent adverse events (AEs) were acute pharyngitis and there were no cases of severe AEs.

CONCLUSIONS

In mild-to-moderate hypertensive patients, low dose (30 mg) fimasartan showed comparable 24-hour BP lowering efficacy compared with valsartan (80 mg). There was no difference in tolerability between two groups.

Bioequivalence of venlafaxine modified-release capsule revisited with an innovative approach using experimental and predictive models

Background: To evaluate the venlafaxine:O-desmethyl venlafaxine (active metabolite) in vivo formation ratio (MR) in three independent bioequivalence (BE) studies consisting of single-dosed (under fasted and fed conditions) and multiple-dosed clinical trials on healthy subjects. The pooled data pharmacokinetic (PK) analysis demonstrates a model to conduct enantiomer/racemate/active metabolite bioanalysis for regulatory submission of bioavailability/bioequivalence (BA/BE) studies using an interesting MR concept. Results: BE was established for all three studies. Moreover, the venlafaxine:O-desmethyl venlafaxine MR for Cmax and AUClast differed by more than 50% for fasted and fed single-dosed studies, while pooled data analysis found the MR for Cmax to be approximately 0.63 and the AUC to be approximately 0.36 for both test and reference drugs. However, negligible variation was observed for both rate and extent of drug and active metabolite absorption into the systemic circulation at steady state, as the MR for both Cmax and AUC was approximately 0.62. Conclusions: The applications/consequences of the above results are immense. First, an achiral assay for venlafaxine and O-desmethyl venlafaxine estimation in human plasma has been justified for the regulatory acceptance of BA/BE studies, supported with both single- and multiple-dosed PK data showing negligible variation in terms of MR at Cmax. Second, the current investigation shows the MR to be within ±10% when compared with the single-dosed reported study on a western population. Third, the racial effect would not lead to any significant clinical outcome using an interchangeable venlafaxine 150-mg capsule manufactured by Ranbaxy with an Efexor 150-mg capsule manufactured by Wyeth. Furthermore, a decision tree is proposed to evaluate if a racemate or an enantiomer drug and active metabolite bioanalysis should be executed for BA/BE regulatory submission using respective achiral or chiral assays when the drug moiety is a racemate or an enantiomer, formulated in modified-release dosage forms.

The population RDH index: a novel vector index and graphical method for statistical assessment of antihypertensive treatment reduction, duration, and homogeneity

Current indices used in the evaluation of antihypertensive treatment duration and homogeneity such as the trough-peak, smoothness index, and normalized smoothness index were designed to be applied to ambulatory blood pressure monitoring recordings from individual participants. Evaluation of antihypertensive treatment in populations is often carried out by calculating these individual indices for each of the participants and providing summarizing statistics about the population, such as the mean and median. We describe a new population vector index and graphical method for the statistical assessment of antihypertensive treatment reduction, duration, and homogeneity (RDH) from ambulatory blood pressure monitoring. The population (RDH) was specifically designed as a tool to evaluate and compare blood pressure coverage offered by antihypertensive drugs over 24 h in populations. The population RDH is a three-component vector index that incorporates information about the reduction, duration, and homogeneity of antihypertensive treatment, as well as their statistical significance over the 24 h period. In addition to defining the RDH index, in this paper we also demonstrate its usefulness and advantages as an index and graphical method for antihypertensive treatment duration and homogeneity assessment by using it to analyze two data sets.

The individual RDH index: a novel vector index for statistical assessment of antihypertensive treatment reduction, duration, and homogeneity

We propose a new vector index for the statistical assessment of antihypertensive treatment duration and homogeneity from ambulatory blood pressure monitoring. We termed this approach for evaluating and comparing blood pressure coverage offered by antihypertensive drugs over 24 h as the reduction-duration-homogeneity index. The reduction-duration-homogeneity index is a three-component vector index that incorporates information about the reduction, duration, and homogeneity of antihypertensive treatment, as well as their statistical significance. The advantages of the reduction-duration-homogeneity index are demonstrated by several comparative examples.

OASIS-HT: design of a pharmacogenomic dose-finding study

Experimental evidence and observations in humans strongly support an interactive role of mutated α-adducin, sodium (Na+)/potassium (K+)-adenosine triphosphatase (ATPase) activity and endogenous ouabain in Na+ homeostasis and the pathogenesis of hypertension. The Ouabain and Adducin for Specific Intervention on Sodium in HyperTension (OASIS-HT) trial is an early Phase II dose-finding study, which will be conducted across 39 European centers. Following a run-in period of 4 weeks without treatment, eligible patients will be randomized to one of five oral doses of rostafuroxin consisting of 0.05, 0.15, 0.5, 1.5, or 5.0 mg/day. Each dose will be compared to a placebo in a double-blind crossover experiment with balanced randomization. Treatment will be initiated with the active drug and continued with placebo or vice versa. Each double-blind period will last 5 weeks. The primary end point is the reduction in systolic blood pressure defined as the average of three clinic readings with the patient in the sitting position. Secondary end points include the reduction in diastolic blood pressure on clinic measurement, the decrease in the 24-h blood pressure, and the incidence of end points related to safety. Secondary objectives are to investigate the dependence of the blood pressure-lowering activity on the plasma concentration of endogenous ouabain and the genetic variation of the enzymes involved in the metabolism of this hormone, and the adducin cytoskeleton proteins. Eligible patients will have Grade I or II systolic hypertension without associated conditions and no more than two additional risk factors. In conclusion, OASIS-HT is a combination of five concurrent crossover studies, one for each dose of rostafuroxin to be studied. To our knowledge, OASIS-HT is the first Phase II dose-finding study in which a genetic hypothesis is driving primary and secondary end points.

The smoothness index, but not the trough-to-peak ratio predicts changes in carotid artery wall thickness during antihypertensive treatment

BACKGROUND

It has recently been demonstrated that the smoothness index (SI) (the ratio between the average of the blood pressure changes computed for each hour of the recording and its standard deviation), a new and reproducible measure of the homogeneity of blood pressure reduction by antihypertensive treatment, has evident advantages over trough-to-peak ratio (T/P) in the prediction of the regression of left ventricular hypertrophy. Therefore we considered it to be worthwhile to compare the ability of SI and T/P to predict changes of the carotid artery intima-media thickness (IMT) during pharmacological treatment in patients with essential hypertension.

METHODS

In 100 patients with essential hypertension, 24 h ambulatory blood pressure and carotid artery IMT were measured after 3 weeks of therapeutic wash-out and after 12 months of antihypertensive treatment (calcium antagonists, diuretics, angiotensin converting enzyme (ACE) inhibitors or beta-blockers). The homogeneity of the effect of treatment over blood pressure was evaluated by computing T/P and SI.

RESULTS

Twenty-four hour blood pressure was significantly reduced by therapy, while, on average, a small but significant increase in indices of carotid artery wall thickness was observed. However, IMT was clearly reduced in patients with high SI. Statistically significant correlations were observed between changes in indices of carotid artery IMT during therapy and SI. No significant correlation was observed between indices of carotid artery morphology and T/P, basal 24 h blood pressure or changes in blood pressure during therapy.

CONCLUSIONS

SI, but not T/P is the predictor of changes in carotid artery wall thickness. The information provided by SI is independent from basal blood pressure values. For carotid artery morphology, the smoothness of blood pressure reduction is even more important than its absolute change.

The effects of mibefradil and enalapril on 24-hour blood pressure control and left ventricular mass in patients with mild to moderate hypertension: double-blind, randomized trial

In this prospective, double-blind, monocenter drug trial, 48 primary care patients with mild to moderate essential hypertension were randomized to mibefradil, 50 mg, titrated to 100 mg, or enalapril, 20 mg, titrated to 2 x 20 mg. Ambulatory 24-h blood pressure measurements (ABPM) and echocardiography were performed at baseline and after 12 weeks' treatment. Complete data from 43 patients were analyzed. Mibefradil (n = 22; titration, 13 patients) reduced mean 24-h ABP from 159+/-14/102+/-7 mm Hg to 140+/-10/89+/-7 mm Hg after 12 weeks. Enalapril (n = 21; titration, six patients) reduced baseline ABP from 156+/-12/100+/-9 mm Hg to 140+/-17/89+/-10 mm Hg (12 weeks). Trough-to-peak ratios in DBP were 86% for mibefradil and 75% with enalapril. Left ventricular mass (LVM) decreased from 199+/-65 to 193+/-62 g [M-mode modified American Society of Echocardiography (ASE)] and from 184+/-65 to 173+/-50 g (truncated ellipsoid method) after 12 weeks in response to mibefradil (p > 0.2), and from 212+/-50 to 196+/-57 g and from 182+/-39 to 170+/-40 g (mean +/- SD, p < 0.02) with enalapril. Mibefradil matched enalapril in 24-h ABP control. Enalapril reduced LVM significantly after 12 weeks (p < 0.02). Mibefradil did not significantly reduce LVM after 12 weeks.

Twenty-four hour antihypertensive efficacy of indapamide, 1.5-mg sustained release: results of two randomized double-blind controlled studies

The antihypertensive efficacy of a 1.5-mg sustained-release formulation (SR 1.5) of indapamide, a diuretic related to thiazide, has been pointed out by using conventional sphygmomanometric measurement 24 h after dosing in clinic, in two large European randomized, double-blind, controlled studies (2 and 3 months). One of these studies was then extended to 12 months, as a complementary open study. Quality-controlled ambulatory blood pressure monitoring (ABPM) data for a total of 216 patients from these studies are presented, including subgroups of hypertensives and responders. Indapamide SR 1.5 achieves an adequate 24-h blood pressure control by significantly reducing the 24-h, diurnal, and nocturnal blood pressures versus baseline, confirming the sphygmomanometric data. The benefit at 2 and 3 months is maintained at 1 year, which confirms the long-term efficacy of SR 1.5 mg. The trough-to-peak ratio--not previously calculated for a diuretic according to international guidelines--meets Food and Drug Administration requirements and confirms the 24-h efficacy of indapamide SR 1.5.

Reproducibility and clinical value of the trough-to-peak ratio of the antihypertensive effect: evidence from the sample study

The objectives of our study were to assess the reproducibility of the trough-to-peak ratio (T/P) and to see whether a high T/P is accompanied by more organ protection or vice versa. The study included 175 (mean+/-SD age, 51+/-9 years) subjects with mild-moderate essential hypertension who had echocardiographic evidence of left ventricular (LV) hypertrophy taken from the SAMPLE study (Study on Ambulatory Monitoring of Blood Pressure and Lisinopril Evaluation), an open-label multicenter study. The study included a 3-week washout pretreatment period, a 12-month treatment period with lisinopril (n=84) or lisinopril plus hydrochlorothiazide (n=91) once daily, and a 4-week placebo follow-up period. Results of 24-hour ambulatory blood pressure monitoring and echocardiographic determination of left ventricular mass index (LVMI) were obtained before and after 3 and 12 months of treatment. T/Ps were computed in each patient by dividing the systolic and diastolic blood pressure changes at trough (changes in the last 2 hours of the monitoring period) by those at peak (average of the 2 adjacent hours with the maximal blood pressure reduction between the 2nd and 8th hour from drug intake) after 3 and 12 months of treatment. Average 24-hour blood pressure was similarly reduced at 3 and 12 months. Trough blood pressure changes at 3 and 12 months were closely correlated, as were the corresponding peak blood pressure changes. However, the 3- and 12-month T/Ps correlated to a lesser degree (r<0.42). Furthermore, the reduction of LVMI induced by treatment was similarly correlated with the treatment-induced reduction in 24-hour average, trough, and peak blood pressures but not with the T/Ps. This was also evident when the contribution to LV hypertrophy regression by 24-hour blood pressure changes and T/Ps was assessed in a multivariate regression analysis. In patients with a T/P >/=0.5 or <0.5, the regression of LVMI was similar. In conclusion, peak and trough blood pressure changes are reproducible and predict the regression of LVMI induced by treatment as well as average 24-hour blood pressure. T/Ps are less reproducible, and their value does not predict regression of organ damage by antihypertensive treatment.

Trough-to-peak ratio and circadian blood pressure profile after treatment with once-daily extended-release diltiazem, 240 mg, in patients with mild-to-moderate essential hypertension

Once-daily diltiazem extended-release 240 mg (Lacerol-HTA Retard) was evaluated for safety, efficacy, and trough-to-peak ratio in a multicenter open study by using 24-h blood pressure (BP) monitoring in mild-to-moderate essential hypertension. After a 4-week washout period, 30 patients (17 men, 13 women) aged 25-76 years, showing a mean daytime diastolic BP (DBP) >90 mm Hg, were treated with diltiazem-ER, 240 mg, given once daily for 8 weeks. Ambulatory BP monitoring was obtained at the end of a 4-week placebo run-in period and during the last week of treatment. A significant reduction of the mean values of clinical BP [161.6 +/- 16.2 to 151.2 +/- 15.6 mm Hg; p < 0.01 for systolic BP (SBP); and 101.1 +/- 4.8 to 93.3 +/- 9.2 mm Hg; p < 0.001 for DBP] was observed at the end of treatment in the group of 30 patients, with no significant changes in heart rate (77.1 +/- 9.9 to 73.1 +/- 11.1 beats/min; p = NS). Likewise, mean values of 24-h SBP, DBP, SBP-load, and DBP-load were significantly reduced. In the group of 21 responders, the average reduction at peak was -18.6 +/- 12.9 mm Hg for SBP and -14.7 +/- 9.5 mm Hg for DBP. The residual effect at trough was -12.2 +/- 14.7 and -8.1 +/- 10 mm Hg, respectively. The trough-to-peak ratio was estimated as 0.66 for SBP and 0.55 for DBP. Long-term variability expressed as the mean standard deviation of BP for the 24-h period was reduced in responders (16.2 +/- 4.3 to 14.6 +/- 2.7 mm Hg for SBP; p = 0.0395; and 12.1 +/- 2.7 to 10.7 +/- 2.5 mm Hg for DBP; p = 0.0019), although no changes were observed in the variation coefficient (10.58-10.57% for SBP and 12.88-12.87% for DBP). We conclude that once-daily diltiazem-ER, 240 mg, was effective and well tolerated. Blood pressure was controlled over the entire period of 24 h, preserving the circadian profile and reducing long-term variability in responders. The significant reduction of both BP values and long-term variability may have implications involving protection from end-organ damage in essential hypertension.

Lisinopril. A review of its pharmacology and clinical efficacy in elderly patients

Lisinopril, the lysine analogue of enalaprilat, is a long-acting angiotensin converting enzyme (ACE) inhibitor which is administered once daily by mouth. The efficacy of lisinopril in reducing blood pressure is well established in younger populations, and many trials now show it to be effective in lowering blood pressure in elderly patients with hypertension. In comparative and non-comparative clinical trials, 68.2 to 89.1% of elderly patients responded (diastolic pressure < or = 90 mm Hg) to > or = 8 weeks' lisinopril treatment. Age-related differences in antihypertensive efficacy do not appear to be clinically significant, and dosages effective in elderly patients tend to range from 2.5 to 40 mg/day. Dosages usually need to be lower in patients with significant renal impairment. In congestive heart failure, lisinopril 2.5 to 20 mg/day increases exercise duration, improves left ventricular ejection fraction and has no significant effect on ventricular ectopic beats. It is similar in efficacy to enalapril and digoxin and similar or superior to captopril on most end-points. Data from the GISSI-3 post-myocardial infarction trial show that lisinopril reduced mortality and left ventricular dysfunction when given for 42 days starting within 24 hours of the onset of infarction symptoms. Results at 6 weeks and 6 months were similar in elderly and younger patients. Elderly patients, however, among other subgroups, exhibited a strong reduction in risk of low ejection fraction after treatment (-25.5%). Economic studies suggest that lisinopril is cost saving compared with other ACE inhibitors in some markets. When given according to the GISSI-3 protocol, lisinopril appears to be one of the less expensive of the successful ACE inhibitor regimens for acute myocardial infarction. In other trials, patients with diabetic nephropathy and hypertension improved or did not deteriorate during lisinopril treatment. Blood pressure was controlled and reductions or trends towards reductions in albuminuria were observed. These reductions were similar to those in diltiazem, nifedipine and verapamil recipients, and greater than those in patients receiving atenolol. Lisinopril appears to reduce mortality in diabetic patients after myocardial infarction and may also improve neuropathy associated with diabetes. Lisinopril is well tolerated and the profile of adverse events seen is typical of ACE inhibitors as a class. There is a tendency for more elderly than younger patients to discontinue treatment, but this trend is not clearly related to the incidence of adverse events in these age groups. Drug interactions occur with few other agents and are usually clinically significant only between lisinopril and either diuretics or lithium. Lisinopril is, thus, an effective treatment for elderly patients with hypertension, congestive heart failure and acute myocardial infarction and has shown promising benefits in patients with diabetic nephropathy.

Ambulatory blood pressure monitoring in clinical trials

Ambulatory blood pressure monitoring is increasingly used in clinical trials. The preliminary threshold values proposed for diagnosing hypertension and adjusting treatment based on ambulatory monitoring cannot yet be widely recommended because they have not been validated in prospective studies. The trough-to-peak or surface ratios may be useful instruments for assessing the duration of action of antihypertensive drugs. Trials with ambulatory monitoring just as clinical experiments based on conventional sphygmomanometry need to be properly controlled, because ambulatory blood pressure measurement is not completely devoid of a placebo effect. Ambulatory compared with conventional blood pressure measurements are characterized by higher reproducibility which makes it possible to reduce sample size in cross-over but not in parallel group trials. Finally, ambulatory monitors used in clinical research should have successfully passed one of the standardized validation protocols.