Importance of various methods of blood pressure measurement in clinical trials

Antihypertensive efficacy of olmesartan medoxomil and candesartan cilexetil assessed by 24-hour ambulatory blood pressure monitoring in patients with essential hypertension

OBJECTIVE

To compare the antihypertensive efficacy of olmesartan medoxomil with that of candesartan cilexetil after 1, 2 and 8 weeks of treatment.

DESIGN AND SETTING

Randomised, double-blind, parallel-group study conducted at 44 centres in Germany, Poland and the Czech Republic.

PATIENTS

643 patients (aged 19-86 years) with mainly mild-to-moderate essential hypertension received active double-blind treatment.

INTERVENTIONS

Following a 2-week placebo run-in, eligible patients were randomly assigned to receive olmesartan medoxomil 20mg (n = 319) or candesartan cilexetil 8mg (n = 324) once daily for 8 weeks.

MAIN OUTCOME MEASURES

Changes from baseline in daytime, 24-hour and night-time diastolic (DBP) and systolic (SBP) blood pressures assessed by ambulatory blood pressure monitoring (ABPM), and changes from baseline in sitting cuff DBP and SBP.

RESULTS

Mean decreases from baseline in daytime DBP by ABPM at weeks 1, 2 and 8 were 6.7, 8.4 and 9.3mm Hg, respectively, in the olmesartan medoxomil group compared with 5.3, 6.0 and 7.8mm Hg, respectively, in the candesartan cilexetil group. The between-group differences were significantly in favour of olmesartan medoxomil at all three timepoints (p </= 0.0126). Significant differences in favour of olmesartan medoxomil were also observed for mean 24-hour DBP and for mean daytime and 24-hour SBP by ABPM. Decreases from baseline in sitting cuff BP at trough were similar in the two groups (15-16mm Hg for DBP and 21mm Hg for SBP). Both treatments were well tolerated.

CONCLUSIONS

Olmesartan medoxomil reduced daytime and 24-hour DBP and SBP, assessed by ABPM, more effectively than candesartan cilexetil at the doses tested. The majority of the treatment effect in both groups was seen after only 1 or 2 weeks of dosing, when the between-group differences were already statistically significant.

Time-dependent effects of imidapril administration in patients with morning hypertension measured as home blood pressure

We investigated the effect of the timing of imidapril administration in patients with morning hypertension (home blood pressure [HBP] in the morning [morning HBP] > or =135/85 mmHg). Eighty-seven patients (mean age, 61 years; 48% women) with morning hypertension each measured HBP in the early morning, before going to bed for the final five days of the observation, and during treatment. Imidapril (2.5 or 5.0 mg) was administered once every morning (n = 57) or at bedtime (n = 30) for four weeks (monotherapy: n = 30, 34%; combined with other antihypertensive drugs: n = 57, 66%). The morning (M) versus evening (E) effect (M/E ratio) and the evening versus morning effect (E/M ratio) were calculated to assess the duration of imidapril action. Morning HBP was significantly reduced (all p < 0.05) except when 2.5 mg of imidapril was administered once at bedtime. The individual M/E ratios expressed as means +/- standard deviation for systolic HBP were 0.9 +/- 0.7 and 0.7 +/- 0.7 for the morning administration of 2.5 and 5.0 mg of imidapril, respectively. The corresponding E/M ratios for bedtime administration were 0.3 +/- 0.5 and 1.0 +/- 0.7, respectively. One daily dose of imidapril taken either in the morning or at bedtime lowered morning HBP, indicating that imidapril is useful for controlling morning hypertension.

Relevance of blood pressure variation in the circadian onset of cardiovascular events

Ambulatory blood pressure monitoring enables the recording of the circadian rhythm of blood pressure under everyday circumstances, with the majority of individuals displaying diurnal variations in both systolic and diastolic blood pressures. During sleep, blood pressure in most people is between 10% and 20% lower than the mean daytime value. On arousal and the start of day-to-day activities, there is a surge in blood pressure that may last for between 4 and 6 h. Extensive evidence shows that ambulatory blood pressure is superior to office values in predicting cardiovascular risk. Cardiovascular events, such as myocardial infarction, ischaemia and stroke are more frequent in the morning hours, soon after waking, than at other times of day. Circadian variations in biochemical and physiological parameters help to explain the link between acute cardiovascular events and the early morning blood pressure surge. Recent observations in elderly Japanese individuals demonstrate that greater early morning blood pressure surges are related to an increased incidence of overt cerebrovascular disease; individuals with the greatest increases in blood pressure on awakening also had the greatest prevalence of silent ischaemic events and were more likely to experience multiple infarcts. Antihypertensive drugs that provide blood pressure control at the time of the early morning surge should provide greater protection against target-organ damage and enhance patient prognosis. Ambulatory blood pressure monitoring may be particularly helpful in assessing the circadian pharmacodynamics of such antihypertensive drugs. The technique has demonstrated, for example, a significantly greater reduction in blood pressure for the last 6 h of the 24-h dosing interval with telmisartan compared with valsartan.

Differential time effect profiles of amlodipine, as compared to valsartan, revealed by ambulatory blood pressure monitoring, self blood pressure measurements and dose omission protocol

Amlodipine and valsartan are once-daily antihypertensive agents. To date, no comparison between these agents given as monotherapies was reported. This study was aimed to evaluate the therapeutic coverage and safety of amlodipine and valsartan in mild-to-moderate hypertensive patients. Multicenter, double-blind, randomized, comparative study. After a 4-week placebo wash-out period, 246 outpatients with office diastolic blood pressure 95 < or = DBP < or =110 mmHg and systolic blood pressure (SBP) < 180 mmHg, in addition to a mean daytime SBP and/or DBP > 135/85 mmHg on 24-h ambulatory blood pressure monitoring (ABPM), were randomly allocated to once-daily amlodipine 5-10 mg or valsartan 40-80 mg, for 12 weeks. In a subgroup of patients, 48-h ABPM were performed at the end of the treatment period. Dose omission was simulated by a single-blind placebo dosing. The primary efficacy end-point was the 24-h trough office BP after 12 weeks of active therapy. The reductions in 24-h trough BP were more pronounced in amlodipine compared with valsartan group as well in office [SBP: -17.8 +/- 10.9 vs. -14.6 +/- 11.2, P = 0.025, DBP: -12.7 +/- 7.2 vs. -10.9 +/- 7.8 mmHg, P = 0.06) as in ambulatory BP (SBP/DBP: -13.0 +/- 13.7/-10.8 +/- 9.1 vs. -7.2 +/- 19.4/-4.9 +/- 13.4 mmHg, P < 0.05). Forty-eight hours after the last active dose, the slope of the morning BP surge (4-9 h) was less steep with amlodipine vs. valsartan [DBP (P < 0.04), SBP (n.s.)]. Ankle edema were more often reported in amlodipine group. These results suggest a superior BP lowering and a longer duration of action with amlodipine compared with valsartan.

Comparison of the effects on 24-h ambulatory blood pressure of valsartan and amlodipine, alone or in combination with a low-dose diuretic, in elderly patients with isolated systolic hypertension (Val-syst Study)

OBJECTIVE

The aim of this study was to compare the time-effect profiles of a once-daily administration of valsartan and amlodipine, each given alone or in combination with hydrochlorothiazide, in terms of ambulatory blood pressure (BP) and heart rate in elderly patients with isolated systolic hypertension.

METHODS

One hundred and sixty-four elderly outpatients with systolic hypertension received valsartan 80 mg (n=79) or amlodipine 5 mg (n=85) once daily for eight weeks, after which the patients with poorly controlled office BP were up-titrated to valsartan 160 mg or amlodipine 10 mg once daily. If their office systolic BP was still >140 mmHg after eight weeks at these doses, 12.5 mg hydrochlorothiazide was added for a further eight weeks. The hourly BP decreases in all of the patients were calculated on the basis of 24-h ambulatory recordings made after the placebo period and at the end of active treatment. The trough/peak ratio and smoothness index were calculated in the responders.

RESULTS

Both the valsartan- and amlodipine-based treatments effectively lowered mean 24-h, daytime and night-time systolic ambulatory BP (all p<0.001) without any significant differences between the two regimens. Ambulatory heart rate decreased in the subjects on valsartan and slightly increased in those on amlodipine (the differences in 24-h and daytime heart rate were significant (p=0.008 and 0.002 respectively). Among the 138 responders, the valsartan-based treatment had a greater anti-hypertensive effect during the daytime hours (p=0.02), a difference that was also significant for average 24-h BP (p=0.02). The mean systolic BP trough/peak ratio was 0.56 in the patients on valsartan, and 0.77 in those on amlodipine (NS). The smoothness index was respectively 1.70 and 1.58 (NS).

CONCLUSIONS

The present results show that both the valsartan- and amlodipine-based treatments lead to a similar long-term reduction in 24-h systolic BP. However, in treatment responders, valsartan has a greater anti-hypertensive effect during the daytime.

Therapeutic effects of evening administration of guanabenz and clonidine on morning hypertension: evaluation using home-based blood pressure measurements

OBJECTIVE

To clarify the effects of bedtime administration of the centrally acting alpha(2)-agonists, guanabenz and clonidine, on morning hypertension.

METHODS

Patients with morning hypertension were assigned to receive once-daily evening administration of guanabenz (2 mg/day, n = 81; 4 mg/day, n = 2) or clonidine (75 microg/day, n = 40; 150 microg/day, n = 10) for 4 weeks, and the blood pressure (BP)-lowering effects of these drugs in the morning and evening were evaluated by assessing self-monitored BP in the home environment. The subjects were then subdivided into different groups according to their evening BP, and the effects of guanabenz and clonidine on evening BP were evaluated further for each group. In addition, as a substitute for the trough/peak ratio, the evening/morning (E/M) ratio was calculated to assess the duration of action of the two alpha(2)-agonists.

RESULTS

Evening dosing with guanabenz or clonidine lowered morning BP significantly. Both drugs decreased evening BP in the subgroup of subjects with a high evening BP, but not in those with a normal evening BP. The individual E/M ratios for guanabenz, but not for clonidine, were significantly greater in those with a high evening BP than in those with a normal evening BP. In the early treatment period, treatment with guanabenz resulted in a higher diastolic E/M ratio in those subjects with a high evening diastolic BP than did treatment with clonidine.

CONCLUSION

The results suggest that evening administration of the central alpha(2)-agonists guanabenz and clonidine effectively suppresses the morning BP elevation in treated hypertensive patients.

An ambulatory blood pressure monitoring study of the comparative antihypertensive efficacy of two angiotensin II receptor antagonists, irbesartan and valsartan

BACKGROUND

The primary objective of this study was to compare the change from baseline in mean diastolic ambulatory blood pressure (ABP) at 24 h post dose (trough measurement) after 8 weeks of treatment with irbesartan or valsartan in subjects with mild-to-moderate hypertension. Secondary objectives included comparing the mean changes from baseline in systolic ABP at trough; 24-h ABP; morning and night-time ABP; self-measured systolic blood pressure (SBP) and diastolic blood pressure (DBP); and office-measured SBP and DBP at trough.

DESIGN

After a 3-week, single blind, placebo lead-in period, 426 subjects were randomized to receive either irbesartan 150 mg or valsartan 80 mg for 8 weeks.

METHODS

Ambulatory blood pressure measurements were obtained at baseline and at week 8. Self-measured morning and evening DBP and SBP readings were obtained at home over a 7-day period at baseline and at week 8. Office-measured seated DBP and SBP measurements were obtained at trough, at baseline, and at week 8.

RESULTS

Irbesartan demonstrated significantly greater reductions than valsartan for mean change from baseline in diastolic ABP at trough (-6.73 versus -4.84 mmHg, respectively; P = 0.035). Irbesartan produced significantly greater reductions than valsartan for mean systolic ABP at trough (-11.62 versus -7.5 mmHg, respectively; P < 0.01) and for mean 24-h diastolic ABP (-6.38 versus -4.82 mmHg, respectively; P = 0.023) and systolic ABP (-10.24 versus -7.76 mmHg; P < 0.01). Irbesartan also produced significantly greater reductions than valsartan for office-measured seated DBP (-10.46 versus 7.28 mmHg, respectively; P < 0.01) and SBP (-16.23 versus -9.96 mmHg, respectively; P < 0.01) and for self-measured morning DBP (-6.28 versus -3.75 mmHg, respectively; P < 0.01) and SBP (-10.21 versus -6.97 mmHg, respectively; P < 0.01). Both drugs were well tolerated.

CONCLUSION

Irbesartan was more effective than valsartan in reducing DBP and SBP at trough and in providing greater overall 24-h blood pressure-lowering efficacy.

Role of blood pressure monitoring in non-pharmacological management of hypertension

Ambulatory blood pressure monitoring (ABPM) and home blood pressure (BP) measurement appear to be useful in the assessment of the effects of non-pharmacological treatment of hypertension because they can detect small changes in BP without observer bias. We studied the effects of various lifestyle modifications using ABPM and home BP measurement in Japanese patients with hypertension. Weight reduction by a hypocaloric diet (average 4 kg) was associated with decreases in 24-h BP (10/4 mmHg) as well as casual BP (9/6 mmHg). The reductions in daytime and night-time BPs were comparable. The effects of daily walking without weight loss on office, home, and 24-h BPs were 2-3/1-2 mmHg. The changes in home and 24-h BPs were more significant than those in office BP. A low-salt diet (25 mmol/day versus 250 mmol/day) decreased 24-h BP by 9/4 mmHg. This hypotensive effect was observed throughout the day. Potassium supplementation (64 mmol/day) decreased office, home and 24-h BPs by 3-4/1-2 mmHg. The changes in home and 24-h BPs were highly significant compared with office BP. Supplementation of magnesium (20 mmol/day) also reduced those BPs significantly. However, the effects of calcium supplementation (25 mmol/day) were small (1-2/1 mmHg) and were significant only for home BP. Alcohol restriction for 4 weeks decreased daytime BP by 3/2 mmHg but increased night-time BP by 4/2 mmHg. Average 24-h BP did not change. Smoking cessation lowered daytime BP without affecting night-time BP. Monitoring of 24-h BP and home BP can detect small changes in BP produced by lifestyle modifications. Ambulatory BP monitoring is particularly suitable in the assessment of changes in lifestyle affecting the circadian pattern of BP such as alcohol consumption and smoking.