A comparison of amlodipine and felodipine extended release in the treatment of hypertension at steady state and after two missed doses

How drug onset rate and duration of action affect drug forgiveness

Medication nonadherence is one of the largest problems in healthcare today, particularly for patients undergoing long-term pharmacotherapy. To combat nonadherence, it is often recommended to prescribe so-called "forgiving" drugs, which maintain their effect despite lapses in patient adherence. Nevertheless, drug forgiveness is difficult to quantify and compare between different drugs. In this paper, we construct and analyze a stochastic pharmacokinetic/pharmacodynamic (PK/PD) model to quantify and understand drug forgiveness. The model parameterizes a medication merely by an effective rate of onset of effect when the medication is taken (on-rate) and an effective rate of loss of effect when a dose is missed (off-rate). Patient dosing is modeled by a stochastic process that allows for correlations in missed doses. We analyze this "on/off" model and derive explicit formulas that show how treatment efficacy depends on drug parameters and patient adherence. As a case study, we compare the effects of nonadherence on the efficacy of various antihypertensive medications. Our analysis shows how different drugs can have identical efficacies under perfect adherence, but vastly different efficacies for adherence patterns typical of actual patients. We further demonstrate that complex PK/PD models can indeed be parameterized in terms of effective on-rates and off-rates. Finally, we have created an online app to allow pharmacometricians to explore the implications of our model and analysis.

How to Choose the Optimal Single-Pill Combination of the First-Line Antihypertensive Drugs? The Benefits of Amlodipine and Telmisartan Combination

In patients with arterial hypertension (AH), an extremely important measure of the effectiveness of antihypertensive drugs (AHD) is not only a direct decrease in blood pressure (BP), but also its stable control throughout the 24 hours, preventing excessive morning surge and increased BP variability, which in turn are recognized cardiovascular risk factors. Currently, in the vast majority of hypertensive patients, the main antihypertensive therapy approach is using single-pill combinations (SPC) of AHD. Among the first-line combinations for a wide range of patients with AH and no special clinical conditions is amlodipine/telmisartan SPC. Distinctive features of these drugs, on the one hand, are unique pharmacological properties, consisting in an ultra-long antihypertensive effects, superior to other AHD in their classes; and on the other hand, there is an large body of evidence from numerous clinical trials confirming their high antihypertensive and target-organ protective potential as well as excellent capabilities in cardiovascular risk reduction. To assess the AHD effectiveness extent, several parameters have been proposed, of which the most rational and useful is the smoothness index, calculated using the ambulatory blood pressure monitoring data. Smoothness index describes both the degree of BP reduction and its distribution during the monitoring period. This index inversely associates with the changes in BP variability, and has predictive value in relation to the hypertension-mediated organ damage regression during different antihypertensive regimens. Amlodipine/telmisartan SPC has also been studied in many trials, including comparative ones with other AHD. In these works its direct powerful antihypertensive effect and a pronounced beneficial impact on the smoothness index have been proved, demonstrating stable BP control throughout the 24 hours (especially in the most dangerous morning hours), and also a decrease in BP variability. Therefore, amlodipine/telmisartan SPC can effectively reduce cardiovascular risk and improve prognosis in patients with AH.

Aliskiren/amlodipine as a single-pill combination in hypertensive patients: subgroup analysis of elderly patients, with metabolic risk factors or high body mass index

Aims

Blood pressure (BP) reduction in hypertensive patients is more difficult to achieve in the elderly or in the presence of comorbidities. We aimed to investigate the efficacy of the single-pill combination (SPC) aliskiren/amlodipine in hypertensive elderly patients, patients with high body mass index (BMI), with at least one metabolic risk factor, and/or type 2 diabetes mellitus (DM).

Methods

In an open-label non-randomized study, patients not adequately controlled by previous treatment with the SPC olmesarten 40/amlodipine 10 (phase 1) were switched to the SPC aliskiren 300/amlodipine 10 (phase 2). The present post-hoc analysis investigated BP reduction in phase 2 in the named subgroups. The EudraCT identifier was 2009-016693-33, ClinicalTrials.gov identifier NCT01113047.

Results

Of the 187 patients not adequately controlled in phase 1 and thus treated with the SPC aliskiren 300/amlodipine 10 in phase 2, 69 were of advanced age (≥65 years), 74 or 89 were overweight or obese (BMI 25.0–29.9 kg/m² or ≥30 kg/m², respectively), 91 had metabolic risk factors (without DM) and 41 had DM. At the beginning of phase 2, depending on the subgroup, baseline SBP was 168–169 mmHg and DBP 103–104 mmHg. After 4 weeks of treatment with aliskiren 300/amlodipine 10, SBP/DBP was lowered by −5.1/−4.8 mmHg in the total cohort, by −5.5/−5.1 mmHg in elderly patients, by −6.7/−5.5 in overweight and by −4.2/−4.5 mmHg in obese patients, by −6.4/−4.7 mmHg in patients with metabolic risk factors without DM, and by −3.3/−5.0 mmHg in DM patients. Limitations include low sample size, limited treatment duration and the fact that the post-hoc defined groups were not mutually exclusive.

Conclusions

In this study reflecting clinical practice, the aliskiren/amlodipine combination achieved effective BP reduction in elderly patients or with metabolic comorbidities, including DM that might be more difficult to treat. This consistent BP lowering pattern facilitates everyday care of patients who receive aliskiren/amlodipine.

Efficacy and tolerability of the single-pill combination of aliskiren 300 mg/amlodipine 10 mg in hypertensive patients not controlled by olmesartan 40 mg/amlodipine 10 mg

OBJECTIVE

We aimed to investigate whether the single pill combination (SPC) of aliskiren 300 mg and amlodipine 10 mg (ALIS 300/AMLO 10) improves blood pressure (BP) reduction in hypertensive patients not adequately controlled by the SPC olmesartan 40 mg and amlodipine 10 mg (OLM 40/AMLO 10).

METHODS

Open-label, non-randomized single-arm study. Patients with stage 2 hypertension were titrated to the SPC OLM 40/AMLO 10 (4-week Phase 1). If hypertension was not controlled they were switched to the SPC ALIS 300/AMLO 10 (4-week Phase 2). In the optional 4-week study extension hydrochlorothiazide (HCT) 12.5 mg was added. EudraCT 2009-016693-33.

RESULTS

In the 342 patients treated, OLM 40/AMLO 10 reduced systolic BP (SBP)/diastolic BP (DBP) by 24.5/14.5 mmHg by end of Phase 1. Those 187 patients with uncontrolled hypertension at the end of Phase 1 switched to ALIS 300/AMLO 10 experienced a further SBP reduction of 5.1 mmHg (95% confidence interval [CI] 3.7 to 6.5, p < 0.0001) and a DBP reduction of 4.8 mmHg (95% CI 3.8 to 5.8; p < 0.0001) in Phase 2. DBP or SBP responder rates were achieved by 51.3% or 44.4%, respectively, SBP and DBP normalization by 36.4%. In 65 patients whose BP was not controlled in Phase 2, SPC ALIS 300/AMLO 10/HCT 12.5 mg decreased SBP/DBP by further 8.1/6.7 mmHg (p < 0.0001 each). No deaths or serious adverse events were noted. Significant adverse events leading to study discontinuation were reported in 2.6% (Phase 1), 2.7% (Phase 2), and 0% (extension). Limitations included the open-label, single-arm non-randomized design, and the relatively short duration.

CONCLUSIONS

In this switch study reflecting clinical practice, patients with moderate hypertension not controlled by the SPC OLM 40/AMLO 10 achieved a clinically and statistically significant reduction of blood pressure from the SPC ALIS 300/AMLO 10 and the optional addition of HCT. All drug combinations were well tolerated.

Impact of prolonged antihypertensive duration of action on predicted clinical outcomes in imperfectly adherent patients: comparison of aliskiren, irbesartan and ramipril

BACKGROUND

Most patients miss occasional doses of antihypertensives. The use of 'forgiving' drugs (i.e. drugs with duration of action longer than the 24-h dosing interval) may allow an adequate blood pressure (BP) reduction to be maintained despite missed doses.

AIM

To quantify the effects of adherence level and duration of action on estimated mean systolic BP (SBP) reduction and cardiovascular disease (CVD) risk.

METHOD

For 1250 patients, we simulated 256-day dosing histories with realistically distributed drug holidays based on a study of electronically monitored dosing records. Adherence was set to the desired level by altering the proportion of doses missed. Mean office SBP-lowering effect (aliskiren 300 mg, -14.1 mmHg; irbesartan 300 mg, -13.3; ramipril 10 mg, -10.1 mmHg) and the rate of SBP increase after stopping treatment (off-rate; aliskiren, 1.0 mmHg/day; irbesartan, 3.6 mmHg/day; ramipril, 4.0 mmHg/day) were taken from the results of a randomised, double-blind trial. SBP was averaged over time and patient to estimate mean reductions in SBP and 10-year CVD risk (Framingham risk equation, baseline absolute 10-year CVD risk: 27%).

RESULTS

Predicted reductions in SBP and CVD risk with aliskiren were larger and less affected by imperfect adherence than the reductions with irbesartan or ramipril. For aliskiren, reducing adherence from 90% to 60% led to a predicted rise in SBP of 1.0 mmHg and three additional CVD events per 1000 treated patients; larger predicted differences were observed for irbesartan (2.5 mmHg; 7.5 events/1000 treated patients) and ramipril (2.2 mmHg; 6.7 events/1000 treated patients).

CONCLUSION

To offset the effects of imperfect adherence, a common challenge with antihypertensives, for better BP management it may be prudent to prescribe 'forgiving' drugs.

Effects on blood pressure and cardiovascular risk of variations in patients' adherence to prescribed antihypertensive drugs: role of duration of drug action

AIM

To determine the effects of imperfect adherence (i.e. occasionally missing prescribed doses), and the influence of rate of loss of antihypertensive effect during treatment interruption, on the predicted clinical effectiveness of antihypertensive drugs in reducing mean systolic blood pressure (SBP) and cardiovascular disease (CVD) risk.

METHOD

The effects of imperfect adherence to antihypertensive treatment regimens were estimated using published patterns of missed doses, and taking into account the rate of loss of antihypertensive effect when doses are missed (loss of BP reduction in mmHg/day; the off-rate), which varies between drugs. Outcome measures were the predicted mean SBP reduction and CVD risk, determined from the Framingham Risk Equation for CVD.

RESULTS

In patients taking 75% of prescribed doses (typical of clinical practice), only long-acting drugs with an off-rate of ∼1 mmHg/day were predicted to maintain almost the full mean SBP-lowering effect throughout the modelled period. In such patients, using shorter-acting drugs (e.g. an off-rate of ∼5-6 mmHg/day) was predicted to lead to a clinically relevant loss of mean SBP reduction of > 2 mmHg. This change also influenced the predicted CVD risk reduction; in patients with a baseline 10-year CVD risk of 27.0% and who were taking 75% of prescribed doses, a difference in off-rate from 1 to 5 mmHg/day led to a predicted 0.5% absolute increase in 10-year CVD risk.

CONCLUSIONS

In patients who occasionally miss doses of antihypertensives, modest differences in the rate of loss of antihypertensive effect following treatment interruption may have a clinically relevant impact on SBP reduction and CVD risk. While clinicians must make every effort to counsel and encourage each of their patients to adhere to their prescribed medication, it may also be prudent to prescribe drugs with a low off-rate to mitigate the potential consequences of missing doses.

The impact of one or two missed doses on the duration of action of combined perindopril and indapamide

To evaluate the persistence of the antihypertensive effect of perindopril 4 mg+indapamide 1.25 mg once daily for up to 72 h using the 'missed-dose' technique. Hypertensive patients were initially treated with perindopril 2 mg+indapamide 0.625 mg once daily. After 4 weeks, the 135 of 216 patients who still had a diastolic BP> or =85 mm Hg went on to receive perindopril 4 mg+indapamide 1.25 mg daily for a further 8 weeks. During either week 9 or 11, placebo was substituted for perindopril 4 mg+indapamide 1.25 mg on either one or two consecutive days to simulate BP changes, which might occur after one or two missed doses. A 24-h ambulatory BP recording was performed at baseline, after 9 or 11 weeks of perindopril+indapamide therapy and during the simulated missed doses, 24- 48 and 48-72 h after the administration of perindopril 4 mg+indapamide 1.25 mg. Significant (P<0.001) reductions in mean (+/-s.d.) 24-h ambulatory BP (mm Hg) during the first 24 h after perindopril 4 mg+indapamide 1.25 mg therapy versus baseline were noted for patients later randomized to the one missed dose (-15.9+/-10.5/-9.4+/-7.6) or two missed dose (-17.4+/-8.7/-10.3+/-5.1) sub-groups. A significant reduction in BP (P<0.001 versus baseline) was still present on the days when placebo was substituted for perindopril 4 mg+indapamide 1.25 mg with decreases in mean 24-h ambulatory BP from 24 to 48 h and 48 to 72 h after dosing being -11.9+/-10.1/-6.9+/-6.2 and -10.6+/-9.9/-5.8+/-5.7, respectively. Use of the 'missed-dose' technique has demonstrated a prolonged antihypertensive effect for perindopril 4 mg+indapamide 1.25 mg for up to 72 h, supporting the use of this combination as therapy for hypertension.

Effect of amlodipine on systolic blood pressure

BACKGROUND

Systolic hypertension is the most common form of hypertension, particularly in people aged >60 years. Caused by decreased compliance of large arteries, systolic hypertension is an independent risk factor for cardiovascular disease. Recent studies have demonstrated that it is more important to control systolic blood pressure (SBP) than diastolic blood pressure (DBP).

OBJECTIVE

The objective of this study was to perform a systematic literature review to examine the effectiveness of amlodipine in lowering SBP in a variety of patient subgroups and clinical settings.

METHODS

The literature review methodology included identifying, selecting, appraising, extracting, and synthesizing primary research studies. Following an a priori protocol, published literature was searched from 1980 to 2001 using 3 electronic databases. A manual review of the reference lists of recent review articles and all accepted studies was performed. Parallel-group, randomized, controlled trials that included at least 10 adults with baseline hypertension (SBP>or=140 mm Hg, DBP>or=90 mm Hg, or both), included at least 1 arm randomized to initial treatment with amlodipine monotherapy, had a minimum treatment duration of 8 weeks, and reported baseline and end-point blood pressure were included.

RESULTS

Of 696 citations identified, 85 primary studies met all inclusion criteria. Comparable treatment arms were pooled, and weightd mean SBP was calculated. In the amlodipine monotherapy arms, which included >5000 patients, SBP decreased by a mean of 17.5 mm Hg from baseline. The effect of amlodipine in reducing SBP was greater in elderly patients (age>or=60 years) and patients with author-defined isolated systolic hypertension. The dose was titrated to achieve the target blood pressure in 73 of 89 amlodipine treatment arms, whereas 16 treatment arms reported fixed doses. The median daily dose was 5 mg (range, 1.25-15 mg) in both the fixed-dose and dose-titration groups.

CONCLUSIONS

In this review of the published literature, amlodipine monotherapy was effective in reducing SBP. Antihypertensive agents such as amlodipine warrant consideration for the management of patients with inadequately controlled SBP.