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

Targeted therapy in chronic diseases using nanomaterial-based drug delivery vehicles

The application of nanomedicines is increasing rapidly with the promise of targeted and efficient drug delivery. Nanomedicines address the shortcomings of conventional therapy, as evidenced by several preclinical and clinical investigations indicating site-specific drug delivery, reduced side effects, and better treatment outcome. The development of suitable and biocompatible drug delivery vehicles is a prerequisite that has been successfully achieved by using simple and functionalized liposomes, nanoparticles, hydrogels, micelles, dendrimers, and mesoporous particles. A variety of drug delivery vehicles have been established for the targeted and controlled delivery of therapeutic agents in a wide range of chronic diseases, such as diabetes, cancer, atherosclerosis, myocardial ischemia, asthma, pulmonary tuberculosis, Parkinson's disease, and Alzheimer's disease. After successful outcomes in preclinical and clinical trials, many of these drugs have been marketed for human use, such as Abraxane®, Caelyx®, Mepact®, Myocet®, Emend®, and Rapamune®. Apart from drugs/compounds, novel therapeutic agents, such as peptides, nucleic acids (DNA and RNA), and genes have also shown potential to be used as nanomedicines for the treatment of several chronic ailments. However, a large number of extensive clinical trials are still needed to ensure the short-term and long-term effects of nanomedicines in humans. This review discusses the advantages of various drug delivery vehicles for better understanding of their utility in terms of current medical needs. Furthermore, the application of a wide range of nanomedicines is also described in the context of major chronic diseases.

Blood pressure-lowering efficacy of monotherapy with thiazide diuretics for primary hypertension

BACKGROUND

Hypertension is a modifiable cardiovascular risk factor. Although it is established that low-dose thiazides reduce mortality as well as cardiovascular morbidity, the dose-related effect of thiazides in decreasing blood pressure has not been subject to a rigorous systematic review. It is not known whether individual drugs within the thiazide diuretic class differ in their blood pressure-lowering effects and adverse effects.

OBJECTIVES

To determine the dose-related decrease in systolic and/or diastolic blood pressure due to thiazide diuretics compared with placebo control in the treatment of patients with primary hypertension. Secondary outcomes included the dose-related adverse events leading to patient withdrawal and adverse biochemical effects on serum potassium, uric acid, creatinine, glucose and lipids.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2014, Issue 1), Ovid MEDLINE (1946 to February 2014), Ovid EMBASE (1974 to February 2014) and ClinicalTrials.gov.

SELECTION CRITERIA

We included double-blind, randomized controlled trials (RCTs) comparing fixed-dose thiazide diuretic monotherapy with placebo for a duration of 3 to 12 weeks in the treatment of adult patients with primary hypertension.

DATA COLLECTION AND ANALYSIS

Two authors independently screened articles, assessed trial eligibility, extracted data and determined risk of bias. We combined data for continuous variables using a mean difference (MD) and for dichotomous outcomes we calculated the relative risk ratio (RR) with 95% confidence interval (CI).

MAIN RESULTS

We included 60 randomized, double-blind trials that evaluated the dose-related trough blood pressure-lowering efficacy of six different thiazide diuretics in 11,282 participants treated for a mean duration of eight weeks. The mean age of the participants was 55 years and baseline blood pressure was 158/99 mmHg. Adequate blood pressure-lowering efficacy data were available for hydrochlorothiazide, chlorthalidone and indapamide. We judged 54 (90%) included trials to have unclear or high risk of bias, which impacted on our confidence in the results for some of our outcomes.In 33 trials with a baseline blood pressure of 155/100 mmHg, hydrochlorothiazide lowered blood pressure based on dose, with doses of 6.25 mg, 12.5 mg, 25 mg and 50 mg/day lowering blood pressure compared to placebo by 4 mmHg (95% CI 2 to 6, moderate-quality evidence)/2 mmHg (95% CI 1 to 4, moderate-quality evidence), 6 mmHg (95% CI 5 to 7, high-quality evidence)/3 mmHg (95% CI 3 to 4, high-quality evidence), 8 mmHg (95% CI 7 to 9, high-quality evidence)/3 mmHg (95% CI 3 to 4, high-quality evidence) and 11 mmHg (95% CI 6 to 15, low-quality evidence)/5 mmHg (95% CI 3 to 7, low-quality evidence), respectively.Direct comparison of doses did not show evidence of dose dependence for blood pressure-lowering for any of the other thiazides for which RCT data were available: bendrofluazide, chlorthalidone, cyclopenthiazide, metolazone or indapamide.In seven trials with a baseline blood pressure of 163/88 mmHg, chlorthalidone at doses of 12.5 mg to 75 mg/day reduced average blood pressure compared to placebo by 12.0 mmHg (95% CI 10 to 14, low-quality evidence)/4 mmHg (95% CI 3 to 5, low-quality evidence).In 10 trials with a baseline blood pressure of 161/98 mmHg, indapamide at doses of 1.0 mg to 5.0 mg/day reduced blood pressure compared to placebo by 9 mmHg (95% CI 7 to 10, low-quality evidence)/4 (95% CI 3 to 5, low-quality evidence).We judged the maximal blood pressure-lowering effect of the different thiazides to be similar. Overall, thiazides reduced average blood pressure compared to placebo by 9 mmHg (95% CI 9 to 10, high-quality evidence)/4 mmHg (95% CI 3 to 4, high-quality evidence).Thiazides as a class have a greater effect on systolic than on diastolic blood pressure, therefore thiazides lower pulse pressure by 4 mmHg to 6 mmHg, an amount that is greater than the 3 mmHg seen with angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs) and renin inhibitors, and the 2 mmHg seen with non-selective beta-blockers. This is based on an informal indirect comparison of results observed in other Cochrane reviews on ACE inhibitors, ARBs and renin inhibitors compared with placebo, which used similar inclusion/exclusion criteria to the present review.Thiazides reduced potassium, increased uric acid and increased total cholesterol and triglycerides. These effects were dose-related and were least for hydrochlorothiazide. Chlorthalidone increased serum glucose but the evidence was unclear for other thiazides. There is a high risk of bias in the metabolic data. This review does not provide a good assessment of the adverse effects of these drugs because there was a high risk of bias in the reporting of withdrawals due to adverse effects.

AUTHORS' CONCLUSIONS

This systematic review shows that hydrochlorothiazide has a dose-related blood pressure-lowering effect. The mean blood pressure-lowering effect over the dose range 6.25 mg, 12.5 mg, 25 mg and 50 mg/day is 4/2 mmHg, 6/3 mmHg, 8/3 mmHg and 11/5 mmHg, respectively. For other thiazide drugs, the lowest doses studied lowered blood pressure maximally and higher doses did not lower it more. Due to the greater effect on systolic than on diastolic blood pressure, thiazides lower pulse pressure by 4 mmHg to 6 mmHg. This exceeds the mean 3 mmHg pulse pressure reduction achieved by ACE inhibitors, ARBs and renin inhibitors, and the 2 mmHg pulse pressure reduction with non-selective beta-blockers as shown in other Cochrane reviews, which compared these antihypertensive drug classes with placebo and used similar inclusion/exclusion criteria.Thiazides did not increase withdrawals due to adverse effects in these short-term trials but there is a high risk of bias for that outcome. Thiazides reduced potassium, increased uric acid and increased total cholesterol and triglycerides.

Benefits of once-daily therapies in the treatment of hypertension

In patients with hypertension, 24-hour blood pressure control is the major therapeutic goal. The number of daily doses is one characteristic of an antihypertensive agent that may affect the adequacy of 24-hour control. One measure of therapeutic coverage is the 24-hour trough-to-peak ratio, which determines the suitability of an agent for once-daily administration. The closer an agent is to a 100% trough-to-peak ratio, the more uniform the 24-hour coverage and therefore blood pressure control. High trough-to-peak ratio, long-acting antihypertensive medications lower blood pressure more gradually, which reduces the likelihood of adverse events attributable to abrupt drug action that occurs with shorter-acting agents. In hypertension, the natural diurnal variation of blood pressure may be altered, including elevated nighttime pressures. An optimal once-daily hypertension therapy would not only lower blood pressure but also normalize any blunted circadian variations in blood pressure. The benefits of once-daily agents with sustained therapeutic coverage may also be explained, in part, by increased patient adherence to simpler regimens as well as lower loss of blood pressure control during virtually inevitable intermittent noncompliance. Studies have demonstrated that once-daily antihypertensive agents have the highest adherence compared with twice-daily or multiple daily doses, including greater adherence to the prescribed timing of doses.

An overview of the pharmacology and clinical efficacy of indapamide sustained release

The relationship between blood pressure (BP) and cardiovascular risk is clearly established; hypertension increases the rate of cardiovascular. High systolic blood pressure (SBP) may be the main parameter involved in cardiovascular morbidity and mortality. The benefit of lowering BP, particularly with diuretics has been proven in many outcome studies. Indapamide, a thiazide-type diuretic, was available for many years at a dosage of 2.5 mg in an immediate release formulation. A new sustained release (SR) formulation has been developed in order to allow the same antihypertensive efficacy with a better acceptability profile. This paper reviews the pharmacology of indapamide 1.5 mg SR from the bench to the bedside. Indapamide has a dual mechanism of action: diuretic effect at the level of the distal tubule in the kidney and a direct vascular effect, both of which contribute to the antihypertensive efficacy of the drug. The SR formulation contains a hydrophilic matrix, which delivers a smoother pharmacokinetic profile. This avoids unnecessary plasma peak concentrations, which may be associated with side effects. Indapamide SR has now been extensively used in hypertensive patients, including those at increased risk, for example elderly or diabetic patients. It has been shown to decrease BP, particularly SBP, with 24-h efficacy, allowing a once-daily dosage. Studies have demonstrated BP lowering to be at least as effective as all major therapeutic classes including the more recent antihypertensive drugs. Beyond BP decrease, indapamide SR has also been shown to protect against hypertensive target-organ damage in the heart and the kidney and to have a favorable metabolic profile. A broad evidence-base has accumulated to support the benefit of indapamide 1.5 mg SR in hypertensive patients, alone or as part of combination therapy, as recommended by the majority of guidelines.

Reversal of left ventricular hypertrophy: what have recent trials taught us?

Regression of left ventricular hypertrophy (LVH) is an important intermediate target for antihypertensive therapy. Thus, several trials and meta-analyses have attempted to compare the effects of different antihypertensive agents on LVH, but flawed study designs and methodologic problems have limited the utility of these studies. PRESERVE (Prospective Randomized Enalapril Study Evaluating Regression of Ventricular Enlargement), LIVE (LVH: Indapamide Sustained Release Versus Enalapril) and LIFE (Losartan Intervention For Endpoint reduction in hypertension) represent a new generation of large well designed trials with the power to compare different antihypertensive drugs. These studies have shown that treatment regimens based on enalapril and a nifedipine gastrointestinal therapeutic system are of similar efficacy (PRESERVE), that indapamide sustained release (SR) is superior to enalapril (LIVE), and that a regimen based on losartan is superior to a regimen based on atenolol (LIFE) in reversing hypertensive LVH. LIVE incorporated on-treatment echocardiographic quality control, with centralized readers blinded for both treatment and sequence of recording. The findings of these rigorous studies, to some extent in disagreement with results of previous meta-analyses, support the notion that antihypertensive drugs need to be judged on their individual effects on important intermediate endpoints such as LVH in well designed and adequately sized studies. However, extrapolation of the results of these studies in terms of class effects could be misleading and should be made with caution.

Metabolic profile of indapamide sustained-release in patients with hypertension: data from three randomised double-blind studies

OBJECTIVE

To evaluate the influence of indapamide sustained-release (SR) 1.5 mg/day, a thiazide-related sulfonamide diuretic, on serum levels of lipids (total cholesterol, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol and triglycerides), glucose and uric acid, and renal function (serum urea and creatinine levels).

METHODS

Pooled data from three randomised, double-blind, controlled studies are analysed. Two of these studies were of short duration (2 and 3 months), one of which included a 9-month nonblind extension phase, and the third was a 12-month prospective study. Short- and long-term metabolic effects of the treatment could thus be analysed. All studies were conducted in patients with mild-to-moderate hypertension; the total population randomised in these studies comprised 1195 patients, of whom 505 had left ventricular hypertrophy (LVH).

RESULTS

After 2 to 3 months' treatment with indapamide SR 1.5 mg/day, there was no significant change from baseline in serum lipid levels and glucose levels. This neutral effect was maintained after 9 and 12 months of treatment. Renal function was not affected by short- or long-term indapamide SR 1.5 mg/day therapy. Serum uric acid level was slightly increased after short-term therapy, but was restored to baseline values during long-term therapy with indapamide SR 1.5 mg/day.

CONCLUSIONS

Indapamide SR 1.5 mg/day has no deleterious effect on glucose metabolism, serum levels of lipids and uric acid, or renal function. This antihypertensive agent can be considered to be an attractive therapeutic choice for all patients with mild-to-moderate hypertension, including the elderly and patients with increased cardiovascular risks, i.e. those with LVH.

Hypertension in the Very Elderly Trial (HYVET): protocol for the main trial

A number of trials and meta-analyses have demonstrated clear benefits of blood pressure (BP) reduction in patients aged <80 years with regard to the reduction in stroke and cardiovascular events. However, a variety of studies have suggested that the positive relationship between BP and cardiovascular mortality is weakened or indeed reversed in the very elderly. Most intervention trials to date have either excluded or not recruited sufficient patients aged > or =80 years to determine whether there is a significant benefit from treatment in this age group. A meta-analysis of intervention trials that recruited patients aged > or =80 years has suggested a benefit in terms of stroke reduction but has also raised the possibility of an increase in total mortality. The benefit to risk ratio therefore needs to be clearly established before recommendations can be made for treating very elderly patients with hypertension. The Hypertension in the Very Elderly Trial (HYVET) pilot recruited 1283 patients aged > or =80 years and showed the feasibility of performing such a trial in this age group. It was a Prospective Randomised Open Blinded End-Points (PROBE) design but the main trial has additional pharmaceutical sponsorship to run a double-blind trial. Therefore, the main trial is a randomised, double-blind, placebo-controlled trial designed to assess the benefits of treating very elderly patients with hypertension. It compares placebo with a low dose diuretic (indapamide sustained release 1.5mg daily) and additional ACE inhibitor (perindopril) therapy if required. As in the pilot trial, the primary end-point is stroke events (fatal and non-fatal) and the trial is designed to determine whether or not a 35% difference occurs between placebo and active treatment. The main objective will be achieved with 90% power at the 1% level of significance. Secondary outcome measures will include total mortality, cardiovascular mortality, cardiac mortality, stroke mortality and skeletal fracture. 2100 patients aged > or =80 years are to be recruited and followed up for an average of 5 years. Entry BP criteria after 2 months of a single-blind placebo run-in period are a sustained sitting systolic BP (SBP) of 160 to 199mm Hg and a diastolic BP of 90 to 109mm Hg. The standing SBP must be >140mm Hg. The trial will be carried out in accordance with the principles of Good Clinical Practice. We describe in detail the protocol for the main trial and discuss the reasons for the changes from the pilot, the use of the drug regimen, and the BP criteria to be used in the trial.

A comparison of indapamide SR 1.5 mg with both amlodipine 5 mg and hydrochlorothiazide 25 mg in elderly hypertensive patients: a randomized double-blind controlled study

OBJECTIVE

To analyse the efficacy of indapamide sustained-release (SR) 1.5 mg in reducing blood pressure versus amlodipine 5 mg and hydrochlorothiazide 25 mg, in elderly hypertensive patients.

DESIGN

Double-blind, randomized, 12 week study using three parallel groups.

SETTING

European teaching hospitals and general practices.

PATIENTS

Randomized patients, (n = 524) including 128 patients with isolated systolic hypertension (ISH); mean age: 72.4 years; mean systolic/diastolic blood pressures (SBP/DBP): 174.5/97.9 mmHg.

MAIN OUTCOME MEASURES

Clinic systolic and diastolic blood pressure variations.

RESULTS

Indapamide SR 1.5 mg demonstrates a similar efficacy to that of amlodipine 5 mg, as well as to that of hydrochlorothiazide 25 mg (equivalence P < 0.001); the mean decreases in SBP/DBP were -22.7/-11.8 mmHg, -22.2/-10.7 mmHg and -19.4/-10.8 mmHg, respectively. In the ISH subgroup, indapamide SR 1.5 mg tends to have greater efficacy than hydrochlorothiazide 25 mg in reducing the SBP (-24.7 versus -18.5 mmHg, respectively; equivalence P = 0.117), while similar results are obtained with amlodipine 5 mg (-23 mmHg, equivalence P < 0.001). The normalization rate was relatively high for indapamide SR 1.5 mg (75.3%), when compared with amlodipine (66.9%) and hydrochlorothiazide (67.3%), especially in the subgroup of isolated systolic hypertensive patients: 84.2 versus 80.0% for amlodipine, and versus 71.4% for hydrochlorothiazide.

CONCLUSIONS

Indapamide SR 1.5 mg shows similar antihypertensive efficacy to amlodipine 5 mg and hydrochlorothiazide 25 mg in elderly hypertensive patients, while in patients with isolated systolic hypertension, indapamide SR 1.5 mg shows a similar efficacy to amlodipine 5 mg but a greater efficacy than hydrochlorothiazide 25 mg.

Regression of left ventricular hypertrophy in hypertensive patients treated with indapamide SR 1.5 mg versus enalapril 20 mg: the LIVE study

OBJECTIVE

To compare the efficacy of indapamide sustained release (SR) 1.5 mg and enalapril 20 mg at reducing left ventricular mass index (LVMI) in hypertensive patients with left ventricular hypertrophy (LVH).

DESIGN

The LIVE study (left ventricular hypertrophy regression, indapamide versus enalapril) was a 1 year, prospective, randomized, double-blind study. For the first time, a committee validated LVH before inclusion, provided on-going quality control during the study, and performed an end-study reading of all echocardiograms blinded to sequence.

SETTING

European hospitals, general practitioners and cardiologists.

PATIENTS

Hypertensive patients aged > or = 20 years with LVH (LVMI in men > 120 g/m2; LVMI in women > 100 g/m2). Data were obtained from 411 of 505 randomized patients.

INTERVENTIONS

Indapamide SR 1.5 mg, or enalapril 20 mg, daily for 48 weeks.

MAIN OUTCOME MEASURES

LVMI variation in the perprotocol population.

RESULTS

Indapamide SR 1.5 mg significantly reduced LVMI (-8.4 +/- 30.5 g/m2 from baseline; P< 0.001), but enalapril 20 mg did not (-1.9 +/- 28.3 g/m2). Indapamide SR 1.5 mg reduced LVMI significantly more than enalapril 20 mg: -6.5 g/m2, P = 0.013 (-4.3 g/m2 when adjusted for baseline values; P = 0.049). Both drugs equally and significantly reduced blood pressures (P< 0.001), without correlation with LVMI changes. Indapamide SR progressively reduced wall thicknesses throughout the 1-year treatment period. In contrast, the effect of enalapril observed at 6 months was not maintained at 12 months.

CONCLUSIONS

Indapamide SR 1.5 mg was significantly more effective than enalapril 20 mg at reducing LVMI in hypertensive patients with LVH.

Clinical positioning of indapamide sustained release 1.5mg in management protocols for hypertension

Indapamide sustained release (SR) 1.5mg is a new galenic formulation that is characterised by a relatively constant plasma concentration at steady state, with only minor fluctuations during the 24-hour period. A dose-titration study of 3 doses of indapamide SR (1.5, 2 and 2.5mg) given once daily has shown that the 3 dosages are equipotent in lowering blood pressure, and have an effect similar to that of indapamide immediate-release (IR) 2.5mg; all were statistically more effective than placebo. The percentage of hypertensive patients whose serum potassium was less than 3.4 mmol/L was significantly lower after indapamide SR 1.5mg than after indapamide IR 2.5mg. Neither indapamide formulation had any significant effects on lipid profile, glucose, urea and serum creatinine; only uric acid was slightly raised during the 2-month study. In an equivalence study, indapamide SR 1.5mg and IR 2.5mg produced similar blood pressure reductions (within the equivalence limit of +/-5mm Hg), whereas the percentage of patients whose serum potassium fell to less than 3.4 mmol/L was lower in the IR 1.5mg group than in the SR 2.5mg group. Antihypertensive treatment with indapamide SR 1.5mg once daily produced reductions in blood pressure in elderly patients with systolic/diastolic or isolated systolic hypertension that were similar to reductions with amlodipine 5 mg/day. The incidence of adverse effects was very low in all studies with indapamide SR 1.5mg and very similar to that in the placebo group, confirming thereby the improvement in the efficacy: tolerance ratio with the new indapamide compound.

Current status of sustained release formulations in the treatment of hypertension. An overview

The principal advantages to be gained from controlling the variables of drug release in sustained release formulations are as follows: (i) a more uniform plasma drug profile with fewer occasions when super- or subtherapeutic concentrations of the drug, or its active metabolite(s), occur; and (ii) a smoother therapeutic response over the dosage interval (provided the time-course of drug effects reflects the plasma concentration-time profile). Clinically, this offers the potential to optimise drug therapy and decrease the occurrence of concentration-related adverse effects. In addition, sustained release formulations may increase the likelihood of patient acceptance of therapy, and a once-daily sustained release formulation of a shorter-acting drug that provides a 'residual' therapeutic response at the end of the dosage interval can provide additional 'cover' in comparison with a once-daily conventional (immediate release) formulation. In the treatment of hypertension, there are potential advantages to be gained from continuous 24-hour control of blood pressure (BP), particularly in view of epidemiological evidence linking the apparent underperformance of antihypertensive therapy in some major intervention trials in reducing the occurrence of coronary heart disease to predicted levels with a relative failure to control diurnal BP fluctuations. In this regard, the concept of the trough:peak ratio as a measure of antihypertensive efficacy has gained increasing acceptance during recent years. A sustained release antihypertensive formulation offering an improved plasma concentration-time profile and an adequately high trough:peak ratio may therefore provide more consistent 24-hour BP-lowering activity, with attenuation of early morning BP surges and maximal target organ protection. This, coupled with the fact that sustained release formulations can also provide economic advantages in cardiovascular therapeutics by lowering overall health expenditure (which more than offsets their usually higher acquisition costs in comparison with immediate release formulations), suggests that they may have an increasingly important role to play in the future.

Low-dose antihypertensive therapy with 1.5 mg sustained-release indapamide: results of randomised double-blind controlled studies. European study group

OBJECTIVE

In accordance with international recommendations on the need to decrease doses of antihypertensive drugs, a low-dose (1.5 mg) sustained-release (SR) formulation of indapamide was developed to optimize the drug's efficacy : safety ratio. The aim of this work was to evaluate the benefit of a low-dose diuretic by consolidating the efficacy and safety results of two clinical trials with a similar design.

PATIENTS AND METHODS

Clinical data were obtained in two European randomized double-blind studies with 690 mild to moderate hypertensive patients (95 mmHg < or = supine diastolic blood pressure < or = 114 mmHg using a mercury sphygmomanometer) treated respectively for 2 and 3 months, with a mean age of 53 and 57 years, 44 and 57% males, mean supine diastolic blood pressure of 100.6 and 102.5 mmHg and mean supine systolic blood pressure of 161.0 and 164.5 mmHg.

RESULTS

The first study, a dose-finding study with indapamide SR at 1.5, 2 and 2.5 mg versus placebo and the immediate-release (IR) formulation of indapamide, showed that the 1.5 mg dosage of the new indapamide formulation had an improved antihypertensive efficacy : safety ratio. The second study confirmed the equivalence of blood pressure reductions with 1.5 mg indapamide SR and 2.5 mg indapamide IR, and better acceptability with 1.5 mg indapamide SR, particularly in the number of patients with serum potassium levels < 3.4 mmol/l, which was reduced by more than 50%. The long-term efficacy of 1.5 mg indapamide SR was observed through a 9-month open-treatment follow-up to the second study.

CONCLUSION

The 1.5 mg SR formulation of indapamide has an improved antihypertensive efficacy : safety ratio, which is in accordance with international recommendations for the use of low-dose antihypertensive drugs and diuretics in first-line therapy of hypertension.