Thiazide diuretics in the treatment of hypertension: an update

Thiazides Attenuate Insulin Secretion Through Inhibition of Mitochondrial Carbonic Anhydrase 5b in β -Islet Cells in Mice

SIGNIFICANCE STATEMENT

Thiazide diuretics (thiazides) are among the most widely prescribed drugs worldwide, but their use is associated with glucose intolerance and new-onset diabetes mellitus. The molecular mechanisms remain elusive. Our study reveals that thiazides attenuate insulin secretion through inhibition of the mitochondrial carbonic anhydrase isoform 5b (CA5b) in pancreatic β cells. We furthermore discovered that pancreatic β cells express only one functional carbonic anhydrase isoform, CA5b, which is critical in replenishing oxaloacetate in the mitochondrial tricarboxylic acid (TCA) cycle (anaplerosis). These findings explain the mechanism for thiazide-induced glucose intolerance and reveal a fundamental role of CA5b in TCA cycle anaplerosis and insulin secretion in β cells.

BACKGROUND

Thiazide diuretics are associated with glucose intolerance and new-onset diabetes mellitus. Previous studies demonstrated that thiazides attenuate insulin secretion, but the molecular mechanisms remain elusive. We hypothesized that thiazides attenuate insulin secretion via one of the known molecular thiazide targets in β cells.

METHODS

We performed static insulin secretion experiments with islets of wild-type, Sodium/chloride co-transporter (NCC) (SLC12A3), and sodium-driven chloride/bicarbonate exchanger (NDCBE) (SLC4A8) knock-out (KO) mice and with murine Min6 cells with individual knockdown of carbonic anhydrase (CA) isoforms to identify the molecular target of thiazides in β cells. CA isoform 5b (CA5b) KO mice were then used to assess the role of the putative thiazide target CA5b in β -cell function and in mediating thiazide sensitivity in vitro and in vivo .

RESULTS

Thiazides inhibited glucose- and sulfonylurea-stimulated insulin secretion in islets and Min6 cells at pharmacologically relevant concentrations. Inhibition of insulin secretion by thiazides was CO 2 /HCO 3- -dependent, not additive to unselective CA inhibition with acetazolamide, and independent of extracellular potassium. By contrast, insulin secretion was unaltered in islets of mice lacking the known molecular thiazide targets NCC or NDCBE. CA expression profiling with subsequent knockdown of individual CA isoforms suggested mitochondrial CA5b as a molecular target. In support of these findings, thiazides significantly attenuated Krebs cycle anaplerosis through reduction of mitochondrial oxaloacetate synthesis. CA5b KO mice were resistant to thiazide-induced glucose intolerance, and thiazides did not alter insulin secretion in CA5b KO islets.

CONCLUSIONS

Thiazides attenuate insulin secretion via inhibition of the mitochondrial CA5b isoform in β cells of mice.

Effect of the combination of bumetanide plus chlorthalidone on hypertension and volume overload in patients with chronic kidney disease stage 4-5 KDIGO without renal replacement therapy: a double-blind randomized HEBE-CKD trial

Background

The co-administration of loop diuretics with thiazide diuretics is a therapeutic strategy in patients with hypertension and volume overload. The aim of this study was to assess the efficacy and safety of treatment with bumetanide plus chlorthalidone in patients with chronic kidney disease (CKD) stage 4–5 KDIGO.

Methods

A double-blind randomized study was conducted. Patients were randomized into two groups: bumetanide plus chlorthalidone group (intervention) and the bumetanide plus placebo group (control) to evaluate differences in TBW, ECW and ECW/TBW between baseline and 30 Days of follow-up. Volume overload was defined as ‘bioelectrical impedance analysis as fluid volume above the 90th percentile of a presumed healthy reference population. The study’s registration number was NCT03923933.

Results

Thirty-two patients with a mean age of 57.2 ± 9.34 years and a median estimated glomerular filtration rate (eGFR) of 16.7 ml/min/1.73 m² (2.2–29) were included. There was decreased volume overload in the liters of total body water (TBW) on Day 7 (intervention: -2.5 vs. control: -0.59, p = 0.003) and Day 30 (intervention: -5.3 vs. control: -0.07, p = 0.016); and in liters of extracellular water (ECW) on Day 7 (intervention: -1.58 vs. control: -0.43, p < 0.001) and Day 30 (intervention: -3.05 vs. control: -0.15, p < 0.000). There was also a decrease in systolic blood pressure on Day 7 (intervention: -18 vs. control: -7.5, p = 0.073) and Day 30 (intervention: -26.1 vs. control: -10, p = 0.028) and in diastolic blood pressure on Day 7 (intervention: -8.5 vs. control: -2.25, p = 0.059) and Day 30 (intervention: -13.5 vs. control: -3.4, p = 0.018).

Conclusion

In CKD stage 4–5 KDIGO without renal replacement therapy, bumetanide in combination with chlorthalidone is more effective in treating volume overload and hypertension than bumetanide with placebo.

Validation of population pharmacokinetic models: a comparison of internal and external validation approaches for hydrochlorothiazide

1. Model evaluation is an important issue in population analyses. Our aim was to perform and illustrate metrics and techniques for internal and external evaluation with an application to population pharmacokinetics of hydrochlorothiazide (HCTZ).2. A nonlinear mixed effects model was used to study the pharmacokinetics of HCTZ. In addition, different types of internal assessment tools and external metrics were used for model evaluation. External evaluation was performed using an alternative dataset that included data from an independent group of subjects. For comparison, a previously published population pharmacokinetic model for HCTZ was applied to the same data.3. A two-compartment model with first-order oral absorption using a constant time delay between administration and absorption and first-order elimination best described HCTZ pharmacokinetics. Age had a statistically significant effect on HCTZ clearance. The final model performed adequately in the internal and external assessment tests. The final model showed better predictive performance than the other previously published HCTZ model.4. Finally, a robust population pharmacokinetic model for HCTZ in adults was constructed and validated internally and externally. Incorporating analytical assessment of nonlinear pharmacokinetics into the modelling may be a promising approach to improve the predictive power of the model.

Pharmacokinetics of Hydrochlorothiazide in Children: A Potential Surrogate for Renal Secretion Maturation

Hydrochlorothiazide (HCTZ) is a thiazide diuretic used in adults and children for the treatment of hypertension and edema. The pharmacokinetic (PK) properties of HCTZ in children are not well characterized, particularly among children with obesity who frequently suffer from hypertension and may, therefore, benefit from HCTZ therapy. HCTZ is excreted in the kidney via organic anion transporters 1 and 3 (OAT1 and OAT3). The ontogeny of OAT1 and OAT3 remain unknown, but HCTZ clearance may serve as a surrogate marker of OAT1 and OAT3 maturation. Population PK modeling was performed in NONMEM, and the model was leveraged to conduct dose-exposure simulations. This study examined 83 plasma samples from 49 participants (69% male) taking enteral HCTZ. The median (range) postnatal age was 6.7 years (0.03-19.5 years), and 17 (34%) participants were obese or morbidly obese. The median (range) dose of HCTZ was 0.654 mg/kg (0.11-1.8 kg) and the median number of doses recorded per participant was 5 (1-8). HCTZ PK was well characterized by a 1-compartment PK model. Body weight and a maturation model based on postmenstrual age were significant covariates for apparent clearance, but the presence of obesity was not. Dosing simulations were performed with a standardized 1mg/kg. Simulated exposure (area under the curve and maximum HCTZ concentrations) decreased with age and was likely due to older children receiving the maximum absolute doses of HCTZ. Further studies with more patients in each age group are required to confirm these PK findings of HCTZ in the children.

Pharmacogenomics of amlodipine and hydrochlorothiazide therapy and the quest for improved control of hypertension: a mini review

Blood pressure (BP) is a complex trait that is regulated by multiple physiological pathways and include but is not limited to extracellular fluid volume homeostasis, cardiac contractility, and vascular tone through renal, neural, or endocrine systems. Uncontrolled hypertension (HTN) has been associated with an increased mortality risk. Therefore, understanding the genetics that underpins and influence BP regulation will have a major impact on public health. Moreover, uncontrolled HTN has been linked to inter-individual variation in the drugs’ response and this has been associated with an individual’s genetics architecture. However, the identification of candidate genes that underpin the genetic basis of HTN remains a major challenge. To date, few variants associated with inter-individual BP regulation have been identified and replicated. Research in this field has accelerated over the past 5 years as a direct result of on-going genome-wide association studies (GWAS) and the progress in the identification of rare gene variants and mutations, epigenetic markers, and the regulatory pathways involved in the pathophysiology of BP. In this review we describe and enhance our current understanding of how genetic variants account for the observed variability in BP response in patients on first-line antihypertensive drugs, amlodipine and hydrochlorothiazide.

Renal secretion of hydrochlorothiazide involves organic anion transporter 1/3, organic cation transporter 2, and multidrug and toxin extrusion protein 2-K

Hydrochlorothiazide (HCTZ) is the most widely used thiazide diuretic for the treatment of hypertension either alone or in combination with other antihypertensives. HCTZ is mainly cleared by the kidney via tubular secretion, but the underlying molecular mechanisms are unclear. Using cells stably expressing major renal organic anion and cation transporters [human organic anion transporter 1 (hOAT1), human organic anion transporter 3 (hOAT3), human organic cation transporter 2 (hOCT2), human multidrug and toxin extrusion 1 (hMATE1), and human multidrug and toxin extrusion 2-K (hMATE2-K)], we found that HCTZ interacted with both organic cation and anion transporters. Uptake experiments further showed that HCTZ is transported by hOAT1, hOAT3, hOCT2, and hMATE2-K but not by hMATE1. Detailed kinetic analysis coupled with quantification of membrane transporter proteins by targeted proteomics revealed that HCTZ is an excellent substrate for hOAT1 and hOAT3. The apparent affinities (K_m) for hOAT1 and hOAT3 were 112 ± 8 and 134 ± 13 μM, respectively, and the calculated turnover numbers (k_cat) were 2.48 and 0.79 s^-1, respectively. On the other hand, hOCT2 and hMATE2-K showed much lower affinity for HCTZ. The calculated transport efficiency (k_cat/K_m) at the single transporter level followed the rank order of hOAT1> hOAT3 > hOCT2 and hMATE2-K, suggesting a major role of organic anion transporters in tubular secretion of HCTZ. In vitro inhibition experiments further suggested that HCTZ is not a clinically relevant inhibitor for hOAT1 or hOAT3. However, strong in vivo inhibitors of hOAT1/3 may alter renal secretion of HCTZ. Together, our study elucidated the molecular mechanisms underlying renal handling of HCTZ and revealed potential pathways involved in the disposition and drug-drug interactions for this important antihypertensive drug in the kidney.

Potential Protective Role of Blood Pressure-Lowering Drugs on the Balance between Hemostasis and Fibrinolysis in Hypertensive Patients at Rest and During Exercise

In patients with hypertension, the triad represented by endothelial dysfunction, platelet hyperactivity, and altered fibrinolytic function disturbs the equilibrium between hemostasis and fibrinolysis and translates into a hypercoagulable state, which underlies the risk of thrombotic complications. This article reviews the scientific evidence regarding some biological effects of antihypertensive drugs, which can protect patients from the adverse consequences of hypertensive disease, improving endothelial function, enhancing antioxidant activity, and restoring equilibrium between hemostatic and fibrinolytic factors. These protective effects appear not to be mediated through blood pressure reduction and are not shared by all molecules of the same pharmacological class.

Genome-wide meta-analysis of SNP-by9-ACEI/ARB and SNP-by-thiazide diuretic and effect on serum potassium in cohorts of European and African ancestry

We evaluated interactions of SNP-by-ACE-I/ARB and SNP-by-TD on serum potassium (K+) among users of antihypertensive treatments (anti-HTN). Our study included seven European-ancestry (EA) (N = 4835) and four African-ancestry (AA) cohorts (N = 2016). We performed race-stratified, fixed-effect, inverse-variance-weighted meta-analyses of 2.5 million SNP-by-drug interaction estimates; race-combined meta-analysis; and trans-ethnic fine-mapping. Among EAs, we identified 11 significant SNPs (P < 5 × 10-8) for SNP-ACE-I/ARB interactions on serum K+ that were located between NR2F1-AS1 and ARRDC3-AS1 on chromosome 5 (top SNP rs6878413 P = 1.7 × 10-8; ratio of serum K+ in ACE-I/ARB exposed compared to unexposed is 1.0476, 1.0280, 1.0088 for the TT, AT, and AA genotypes, respectively). Trans-ethnic fine mapping identified the same group of SNPs on chromosome 5 as genome-wide significant for the ACE-I/ARB analysis. In conclusion, SNP-by-ACE-I /ARB interaction analyses uncovered loci that, if replicated, could have future implications for the prevention of arrhythmias due to anti-HTN treatment-related hyperkalemia. Before these loci can be identified as clinically relevant, future validation studies of equal or greater size in comparison to our discovery effort are needed.

Effectiveness of thiazides on serum and urinary calcium levels and bone mineral density in patients with osteoporosis: a systematic review and meta-analysis

Objective

Osteoporosis is the most common metabolic bone disease and a major public health problem worldwide. Thiazides are widely used as antihypertensive agents with good tolerability and efficacy. Furthermore, thiazides have long been regarded as candidates for the prevention of postmenopausal bone loss. However, there is insufficient evidence that thiazides have a sustained beneficial effect on preserving bone mass and preventing osteoporosis to date.

Materials and methods

We searched the PubMed, the Cochrane Library, and Embase in June 2018 for randomized controlled trials on the use of thiazides to treat osteoporosis. Continuous outcomes are presented as the standardized mean difference (SMD) and 95% CI. Furthermore, P-values <0.05 were considered significant.

Results

Five trials with 756 patients were randomly assigned in the five trials included in this meta-analysis. Serum calcium level was higher in the thiazide group than in the control group (SMD 0.33, 95% CI [0.16, 0.50]), and urinary calcium level was significantly lower in the thiazide group (SMD −0.35, 95% CI [−0.52, −0.17]). There was no significant difference in bone mineral density between the two groups (SMD 0.19, 95% CI [−0.16, 0.54]).

Conclusion

Thiazides might play a role in preserving bone mass and be effective in the prevention and treatment of osteoporosis. Future high-quality trials are needed to confirm our findings in the future.

Hydrochlorothiazide ameliorates polyuria caused by tolvaptan treatment of polycystic kidney disease in PCK rats

BACKGROUND

Tolvaptan is an effective treatment for polycystic kidney disease (PKD), but also causes unfortunate polyuria. Hydrochlorothiazide (HCTZ) has been shown to reduce urine volume in nephrogenic diabetes insipidus, raising the possibility that HCTZ could also be effective in reducing tolvaptan-induced polyuria. In this study, we examined the combined administration of HCTZ and tolvaptan.

METHODS

Male PCK rats were divided into four groups of normal chow (Cont), normal chow plus tolvaptan, gavage HCTZ treatment, and tolvaptan + HCTZ. Biochemical examinations of the plasma and urine were performed as well as histological and molecular (mRNA and protein expression) analyses.

RESULTS

Groups treated with tolvaptan had significantly higher 24 h urine excretion, which was significantly reduced in the tolvaptan + HCTZ group after 2 weeks. Cyst size, pERK protein expression, and Cyclin D1 mRNA expression were all significantly reduced in both the tolvaptan and tolvaptan + HCTZ groups, indicating that HCTZ did not affect the beneficial functions of tolvaptan. Notably, aquaporin 2 redistribution from the apical to intracellular domains was observed in tolvaptan-treated rats and was partially reversed in the tolvaptan + HCTZ group. The renal glomerular filtration rate was reduced in the tolvaptan + HCTZ group. Significantly lowered mRNA expression of neuronal nitric oxide synthase, prostaglandin E synthase 2 and renin were also found in the medulla, but not in the cortex.

CONCLUSION

HCTZ reduces tolvaptan-induced polyuria without altering its beneficial effects on PKD. This novel therapeutic combination could potentially lead to better PKD treatments and improved quality of life for the affected patients.

Type 2 Diabetes and Thiazide Diuretics

PURPOSE OF REVIEW

In patients with prediabetes or type 2 diabetes, the use of thiazides as antihypertensive agents has been challenged because associated metabolic adverse events, including new-onset diabetes.

RECENT FINDINGS

These metabolic disturbances are less marked with low-dose thiazides and, in most but not all studies, with thiazide-like diuretics (chlorthalidone, indapamide) than with thiazide-type diuretics (hydrochlorothiazide). In post hoc analyses of subgroups of patients with hypertension and type 2 diabetes, thiazides resulted in a significant reduction in cardiovascular events, all-cause mortality, and hospitalization for heart failure compared to placebo and generally were shown to be non-inferior to other antihypertensive agents. Benefits attributed to thiazide diuretics in terms of cardiovascular event reduction outweigh the risk of worsening glucose control in type 2 diabetes and of new-onset diabetes in non-diabetic patients. Thiazides still play a key role in the management of patients with type 2 diabetes and hypertension.

Common medications used by patients with type 2 diabetes mellitus: what are their effects on the lipid profile?

Dyslipidemia is the most fundamental risk factor for atherosclerotic cardiovascular disease (ASCVD). In clinical practice, many commonly prescribed medications can alter the patient's lipid profile and, potentially, the risk for ASCVD-either favorably or unfavorably. The dyslipidemia observed in type 2 diabetes mellitus (T2DM) can be characterized as both ominous and cryptic, in terms of unrecognized, disproportionately elevated atherogenic cholesterol particle concentrations, in spite of deceptively and relatively lower levels of low-density lipoprotein cholesterol (LDL-C). Several factors, most notably insulin resistance, associated with the unfavorable discordance of elevated triglyceride (TG) levels and low levels of high-density lipoprotein cholesterol (HDL-C), have been shown to correlate with an increased risk/number of ASCVD events in patients with T2DM. This review focuses on known changes in the routine lipid profile (LDL-C, TGs, and HDL-C) observed with commonly prescribed medications for patients with T2DM, including antihyperglycemic agents, antihypertensive agents, weight loss medications, antibiotics, analgesics, oral contraceptives, and hormone replacement therapies. Given that the risk of ASCVD is already elevated for patients with T2DM, the use of polypharmacy may warrant close observation of overall alterations through ongoing lipid-panel monitoring. Ultimately, the goal is to reduce levels of atherogenic cholesterol particles and thus the patient's absolute risk.

Clinically and pharmacologically relevant interactions of antidiabetic drugs

Patients with type 2 diabetes mellitus often require multifactorial pharmacological treatment due to different comorbidities. An increasing number of concomitantly taken medications elevate the risk of the patient experiencing adverse drug effects or drug interactions. Drug interactions can be divided into pharmacokinetic and pharmacodynamic interactions affecting cytochrome (CYP) enzymes, absorption properties, transporter activities and receptor affinities. Furthermore, nutrition, herbal supplements, patient's age and gender are of clinical importance. Relevant drug interactions are predominantly related to sulfonylureas, thiazolidinediones and glinides. Although metformin has a very low interaction potential, caution is advised when drugs that impair renal function are used concomitantly. With the exception of saxagliptin, dipeptidyl peptidase-4 (DPP-4) inhibitors also show a low interaction potential, but all drugs affecting the drug transporter P-glycoprotein should be used with caution. Incretin mimetics and sodium-glucose cotransporter-2 (SGLT-2) inhibitors comprise a very low interaction potential and are therefore recommended as an ideal combination partner from the clinical-pharmacologic point of view.

Drug-Induced Diabetes Mellitus: Evidence for Statins and Other Drugs Affecting Glucose Metabolism

Abnormalities of glucose metabolism and glucose tolerance, either because of a reduction in tissue sensitivity to insulin (e.g., in liver, skeletal muscle, and adipose tissues) and/or a reduction in pancreatic insulin secretion, are associated with a number of unwanted health outcomes. Even small increases in circulating glucose levels (often described as dysglycemia or prediabetes) may confer an increased risk of cardiovascular (CV) disease and progression to overt type 2 diabetes. A number of drug therapies, many of them used long term in chronic disease management, have adverse effects on glucose metabolism, diabetes risk, and glycemic control among patients with preexisting diabetes. In this study, we review the evidence, underlying mechanisms, and the clinical significance of drug-related adverse effects on glucose metabolism.

Drug Interactions in Parkinson's Disease: Safety of Pharmacotherapy for Arterial Hypertension

BACKGROUND

Parkinson's disease (PD) is a progressive neurodegenerative disorder of the central nervous system, observed in patients aged older than 50 years. In this study, we review interactions between therapies used in PD and selected antihypertensive agents. Moreover, in view of the lack of evidence-based recommendations regarding the pharmacotherapy of arterial hypertension in PD patients, we propose effective and safe therapeutic algorithms for these two coexisting conditions.

METHOD

We used the "Drug interactions" database affiliated with the Ministry of Health, which allows for the identification of interactions between compared active compounds. The database is updated on a monthly basis and all data are consistent with current legislation. For information about interactions, we additionally added data from the British National Formulary, a joint publication of the British Medical Association and the Royal Pharmaceutical Society of Great Britain. In this analysis, we also used data from Micromedex^®, Cerner Multum™, Wolters Kluwer™, Lexicomp^® and Stockley's^®. We analysed the potential interactions between antihypertensive and anti-parkinsonian agents included in respective guidelines on the pharmacotherapy of these conditions.

RESULTS

Our analysis revealed the lack of clinically relevant interactions between preparations of levodopa and benserazide (used for the treatment of PD) and angiotensin-converting enzyme inhibitors, antagonists of AT₁ receptor for angiotensin II or antagonists of β-adrenoreceptors (β-adrenolytics).

CONCLUSION

To avoid major drug-to-drug interactions, patients receiving preparations of levodopa and benserazide should be prescribed angiotensin-converting enzyme inhibitors, antagonists of AT₁ receptor for angiotensin II, or antagonists of β-adrenoreceptors (β-adrenolytics) as the first-line agents of antihypertensive treatment.

Antihypertensive combination therapy in primary care offices: results of a cross-sectional survey in Switzerland

BACKGROUND

Most hypertensive patients need more than one substance to reach their target blood pressure (BP). Several clinical studies indicate the high efficacy of antihypertensive combinations, and recent guidelines recommend them in some situations even as initial therapies. In general practice they seem widespread, but only limited data are available on their effectiveness under the conditions of everyday life. The objectives of this survey among Swiss primary care physicians treating hypertensive patients were: to know the frequency of application of different treatment modalities (monotherapies, free individual combinations, single-pill combinations); to see whether there are relationships between prescribed treatment modalities and patient characteristics, especially age, treatment duration, and comorbidities; and to determine the response rate (percentage of patients reaching target BP) of different treatment modalities under the conditions of daily practice.

METHODS

This cross-sectional, observational survey among 228 randomly chosen Swiss primary care physicians analyzed data for 3,888 consecutive hypertensive patients collected at one single consultation.

RESULTS

In this survey, 31.9% of patients received monotherapy, 41.2% two substances, 20.9% three substances, and 4.7% more than three substances. By combination mode, 34.9% took free individual combinations and 30.0% took fixed-dose single-pill combinations. Combinations were more frequently given to older patients with a long history of hypertension and/or comorbidities. In total, 67.8% of patients achieved their BP target according to their physician's judgment. When compared, single-pill combinations were associated with a higher percentage of patients achieving target BP than free individual combinations and monotherapies for the total sample and for patients with comorbidity.

CONCLUSION

Antihypertensive combination therapy was widely used in Swiss primary care practices. The number of prescribed substances depended on age, treatment duration, and type and number of comorbidities. Although the response rate was generally modest under the conditions of daily practice, it was higher for single-pill combinations than for monotherapies and free individual combinations. Further studies are needed to confirm these observations.

Genetic predictors of thiazide-induced serum potassium changes in nondiabetic hypertensive patients

Thiazide diuretics are associated with an increased risk of hypokalemia. However, pharmacogenetic markers of thiazide-induced changes in serum potassium are not well studied. The aim of this study was to investigate possible predictors of serum potassium changes after thiazide treatment. Nondiabetic hypertensive patients with a systolic blood pressure of ⩾140 or a diastolic blood pressure of ⩾90 mm Hg were enrolled in our study. After 2 weeks of lifestyle modification and diet instruction, patients with persistently elevated blood pressure were given 50 mg of hydrochlorothiazide every morning for 2 weeks. Twenty single-nucleotide polymorphism (SNP) markers were selected from two candidate genes, SLC12A3 and WNK1. Serum potassium levels were checked before and after hydrochlorothiazide treatment. A total of 75 patients eventually qualified for enrollment in our study. They received 50 mg of hydrochlorothiazide every morning for 2 weeks. Six SNPs in WNK1 (rs11064524, rs4980973, rs12581940, rs880054, rs953361, and rs10849582) were correlated with decreases in serum potassium. None of the SLC12A3 polymorphisms were correlated with decreases in serum potassium. After Bonferroni's correction, only rs4980973 was correlated with decreases in serum potassium (corrected P=0.014). Multivariate stepwise linear regression analysis revealed that the changes in serum potassium levels were independently associated with the baseline potassium level (β=-0.587, 95% confidence interval=-0.875--0.299, P=0.0001) and WNK1 rs4980973 (A/A and A/G vs. G/G, β=-0.418, 95% confidence interval=-0.598--0.237, P=0.00002). In conclusion, the baseline potassium level and the WNK1 rs4980973 polymorphism were independent predictors of decreases in serum potassium after short-term hydrochlorothiazide treatment in nondiabetic hypertensive patients.

Systemic delivery of β-blockers via transdermal route for hypertension

Hypertension is the most common cardiovascular disease worldwide. Moreover, management of hypertension requires long-term treatment that may result in poor patient compliance with conventional dosage forms due to greater frequency of drug administration. Although there is availability of a plethora of therapeutically effective antihypertensive molecules, inadequate patient welfare is observed; this arguably presents an opportunity to deliver antihypertensive agents through a different route. Ever since the transdermal drug delivery came into existence, it has offered great advantages including non-invasiveness, prolonged therapeutic effect, reduced side effects, improved bioavailability, better patient compliance and easy termination of drug therapy. Attempts were made to develop the transdermal therapeutic system for various antihypertensive agents, including β-blockers, an important antihypertensive class. β-blockers are potent, highly effective in the management of hypertension and other heart ailments by blocking the effects of normal amounts of adrenaline in the heart and blood vessels. The shortcomings associated with β-blockers such as more frequent dose administration, extensive first pass metabolism and variable bioavailability, make them an ideal candidate for transdermal therapeutic systems. The present article gives a brief view of different β-blockers formulated as transdermal therapeutic system in detail to enhance the bioavailability as well as to improve patient compliance. Constant improvement in this field holds promise for the long-term success in technologically advanced transdermal dosage forms being commercialized sooner rather than later.

Impact of chronic diuretic treatment on glucose homeostasis

BACKGROUND

The use of diuretics for hypertension has been associated with unfavorable changes in cardiovascular risk factors, such as uric acid and glucose tolerance, though the findings in the literature are contradictory.

METHODS

This study investigated whether diuretic use is associated with markers of metabolic and cardiovascular risk, such as insulin-resistance and uric acid, in a cohort of adults without known diabetes and/or atherosclerotic cardiovascular disease. Nine hundred sixty-nine randomly selected participants answered a questionnaire on clinical history and dietary habits. Laboratory blood measurements were obtained in 507 participants.

RESULTS

Previously undiagnosed type 2 diabetes was recognized in 4.2% of participants who were on diuretics (n = 71), and in 2% of those who were not (n = 890; P = 0.53). Pre-diabetes was diagnosed in 38% of patients who were on diuretics, and in 17.4% (P < 0.001) of those who were not. Multivariate analysis showed that insulin-resistance (HOMA-IR) was associated with the use of diuretics (P = 0.002) independent of other well-known predisposing factors, such as diet, physical activity, body mass index, and waist circumference. The use of diuretics was also independently associated with fasting plasma glucose concentrations (P = 0.001) and uric acid concentrations (P = 0.01).

CONCLUSIONS

The use of diuretics is associated with insulin-resistance and serum uric acid levels and may contribute to abnormal glucose tolerance.

Pharmacokinetics and Pharmacodynamics of Drospirenone-Estradiol Combination Hormone Therapy Product Coadministered With Hydrochlorothiazide in Hypertensive Postmenopausal Women

The effects of combination hormone therapy of drospirenone (DRSP), a novel progestin with antialdosterone properties, and 17beta-estradiol (E2) on hydrochlorothiazide (HCTZ) pharmacokinetics/pharmacodynamics versus placebo were investigated in a double-blind, placebo-controlled, crossover study. Thirty-six postmenopausal women with stage 1 hypertension maintained on 25 mg of HCTZ once daily were randomized to receive either 3 mg of DRSP/1 mg of E2 or placebo once daily for 4 weeks. Plasma HCTZ, serum DRSP, E2, potassium, aldosterone, and plasma renin activity were determined at baseline and after 4 weeks. Results showed that the combination of DRSP/E2 plus 25 mg of HCTZ is safe and well tolerated in hypertensive postmenopausal women. The pharmacokinetics of HCTZ were not affected by coadministration of DRSP/E2. The geometric mean ratios and 90% confidence intervals ([HCTZ + DRSP/E2]/[HCTZ + placebo]) for HCTZ (a) area under the serum/plasma concentration-time curve from 0 to 24 hours and (b) maximum plasma concentration were 101 (90.7, 112) and 103 (92.8, 115), respectively. In the HCTZ + DRSP/E2 group, serum potassium, aldosterone, and plasma renin activity all increased in a manner marginally consistent with a beneficial antialdosterone effect, counteracting the HCTZ-induced potassium loss and lowering both systolic and diastolic blood pressure. No dose adjustment is required when DRSP/E2 is added to antihypertensive therapy with HCTZ in hypertensive postmenopausal women.

Clinical significance of incident hypokalemia and hyperkalemia in treated hypertensive patients in the antihypertensive and lipid-lowering treatment to prevent heart attack trial

Concerns exist that diuretic-induced changes in serum potassium may have adverse effects in hypertensive patients. The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial, a large practice-based clinical trial, made it possible to examine consequences of observed changes in potassium during care in conventional practice settings. Normokalemic participants randomized to chlorthalidone (C) versus amlodipine or lisinopril as a first-step drug were stratified by year-1 potassium. Postyear-1 outcomes among hypokalemics (potassium, <3.5 mmol/L) and hyperkalemics (potassium, >5.4 mmol/L) were compared with normokalemics (potassium, 3.5-5.4 mmol/L). Year-1 hypokalemia incidence was 6.8%; incidence in C (12.9%) differed from amlodipine (2.1%; P<0.001) and lisinopril (1.0%; P<0.01). Hyperkalemia incidence (2.0%) was greater in lisinopril (3.6%) than in C (1.2%; P<0.01) or amlodipine (1.9%; P<0.01). Coronary heart disease occurred in 8.1% with hypokalemia, 8.0% with normokalemia, and 11.1% with hyperkalemia. Overall, mortality was higher in hypokalemics than in normokalemics (Cox hazard ratio, 1.21 [95% CI, 1.02-1.44]) with statistically significant (interaction, P<0.01) disparity in hazard ratios for the 3 treatment arms (hazard ratios, C=1.21, amlodipine=1.60, lisinopril=3.82). Hyperkalemia was associated with increased risk of combined cardiovascular disease (hazard ratio, 1.58 [95% CI, 1.15-2.18]) without significant treatment interactions. In conventional practice settings, the uncommon appearance of hyperkalemia was associated with increased cardiovascular disease risk. Hypokalemia was associated with increased mortality; however, the statistically significant heterogeneity in hazard ratios across treatment groups strongly suggests that the observed increase in mortality is unrelated to the specific effects of C. Thus, for most patients, concerns about potassium levels should not influence the clinician's decision about initiating hypertension treatment with low-moderate doses of thiazide diuretics (12.5-25.0 mg of C).

The effect of fat intake and antihypertensive drug therapy on serum lipid profile: a cross-sectional survey of serum lipids in male and female hypertensives

The present study aimed to investigate the effect of betablocker with diuretics therapy on serum cholesterol and high density lipoprotein (HDL-C) lipids in cross-sectional data (age, sex, weight, and body mass index (BMI), smoking/alcoholic consumption) and supplemented vegetarian low-fat diet with daily low fat energy intake, salt intake, duration of drug therapy, and serum protein as effective measures of lowering blood pressure among hypertensives in both males and females. Hypertensive patients on betablocker and/or thiazide therapy were compared in cross-section study with their age, blood pressure, fat intake, serum lipid profile, BMI, and serum albumin in males and females. Dietary fat intake and serum lipid profile were income related. Betablocker and diuretics therapy in combination with dietary fat intervention was beneficial for prolonged dyslipidemia control. Serum cholesterol level was main contributing factor dependent on BMI, duration of drug, and socio-economic factors. Fat intake contributed in hypertension and serum cholesterol levels. A cross-sectional data analysis showed beneficial effects of "low fat-salt-smoking-alcohol consumption and combined polyunsaturated fatty acid with antihypertensive therapy approach" to keep normal dyslipidemia and hypertension. Low fat intake, low salt, smoking, alcohol consumption, and combination of dietary oil supplements with lipid betablockers and diuretic modulators were associated with low hypertension and controlled dyslipidemia in Asian sedentary population.

Cardiovascular disease and intensive glucose control in type 2 diabetes mellitus: moving practice toward evidence-based strategies

Type 2 diabetes mellitus (T2DM) is associated with a high risk of complications, essentially macrovascular events. Surprisingly, the effect of improved glucose control on coronary and cerebrovascular complications and the target level of glycated hemoglobin (HbA(1c)) in this population remains questionable. We here report the results of 4 recently published randomized controlled trials (ACCORD, ADVANCE, VADT, UKPDS post-trial), which did not demonstrate a significant reduction of cardiovascular events in the intensive group compared to the standard group. On the contrary, in ACCORD, the study with the most ambitious goal (HbA(1c) < 6%), the overall and cardiovascular mortality was greater in the intensive group, although the risk of microangiopathic complications, especially nephropathy, was significantly decreased. VADT suggests that one possibility for the lack of observed effect of intensive therapy could be that the cardiovascular benefit is delayed. This contrasts strongly with the long-term postintervention outcomes of UKPDS, which show a persistent benefit of glycemic control during 10 years of post-trial follow-up ('legacy effect'). Therefore, the best way to protect patients with T2DM against coronary and cerebrovascular disease is to target all cardiovascular risk factors as early as possible by an individualized approach.

Cardiovascular disease and intensive glucose control in type 2 diabetes mellitus: moving practice toward evidence-based strategies

Type 2 diabetes mellitus (T2DM) is associated with a high risk of complications, essentially macrovascular events. Surprisingly, the effect of improved glucose control on coronary and cerebrovascular complications and the target level of glycated hemoglobin (HbA_1c) in this population remains questionable. We here report the results of 4 recently published randomized controlled trials (ACCORD, ADVANCE, VADT, UKPDS post-trial), which did not demonstrate a significant reduction of cardiovascular events in the intensive group compared to the standard group. On the contrary, in ACCORD, the study with the most ambitious goal (HbA_1c < 6%), the overall and cardiovascular mortality was greater in the intensive group, although the risk of microangiopathic complications, especially nephropathy, was significantly decreased. VADT suggests that one possibility for the lack of observed effect of intensive therapy could be that the cardiovascular benefit is delayed. This contrasts strongly with the long-term postintervention outcomes of UKPDS, which show a persistent benefit of glycemic control during 10 years of post-trial follow-up (‘legacy effect’). Therefore, the best way to protect patients with T2DM against coronary and cerebrovascular disease is to target all cardiovascular risk factors as early as possible by an individualized approach.

Should diuretics always be included as initial antihypertensive management in early-stage CKD?

PURPOSE OF REVIEW

This review focuses on the need for combined antihypertensive therapy drugs in patients with chronic kidney disease and the relevance of diuretics.

RECENT FINDINGS

Chronic kidney disease is a high-risk situation characterized by the presence of volume overload-related hypertension, micro/macroalbuminuria and other traditional and nontraditional risk factors. To achieve the blood pressure goal in these patients, combined antihypertensive therapy (including diuretics) is usually required.

SUMMARY

Extracellular volume expansion is an important, if not the most important, contributing factor to hypertension seen in chronic kidney disease. Protection against progression of renal dysfunction has two main requirements: strict blood pressure control and lowering proteinuria to values as near to normal as possible. Diuretics have been a useful tool to manage volume overload and to achieve strict blood pressure control in patients with chronic kidney disease. Albeit other blood pressure-lowering agents offer additional favorable effects independently of blood pressure changes, diuretics will continue to be used in these patients.

Coriander fruit exhibits gut modulatory, blood pressure lowering and diuretic activities

AIM OF THE STUDY

Coriander (Coriandrum sativum) is traditionally used for various gastrointestinal and cardiovascular disorders and this study was designed to rationalize its use in dyspepsia, abdominal colic, diarrhea, hypertension and as diuretic.

MATERIALS AND METHODS

Coriander crude extract (Cs.Cr) was evaluated through in vitro and in vivo techniques.

RESULTS

Cs.Cr caused atropine sensitive stimulatory effect in isolated guinea-pig ileum (0.1-10 mg/ml). In rabbit jejunum preparations, Cs.Cr evoked a similar contractile response but in the presence of atropine, it exhibited relaxation against both spontaneous and high K(+) (80 mM)-induced contractions as well as shifted the Ca(2+) concentration-response curves to right, similar to that caused by verapamil. Cs.Cr (1-30 mg/ml) caused fall in arterial blood pressure of anesthetized animals, partially blocked by atropine. Cs.Cr produced vasodilatation against phenylephrine and K(+) (80 mM)-induced contractions in rabbit aorta and cardio-depressant effect in guinea-pig atria. Cs.Cr produced diuresis in rats at 1-10mg/kg. Bio-assay-directed fractionation revealed the separation of spasmogenic and spasmolytic components in the aqueous and organic fractions respectively.

CONCLUSIONS

These results indicate that coriander fruit exhibits gut stimulatory, inhibitory and hypotensive effects mediating possibly through cholinergic, Ca(2+) antagonist and the combination of these mechanisms respectively. Diuretic activity adds value to its use in hypertension.

Do thiazides worsen metabolic syndrome and renal disease? The pivotal roles for hyperuricemia and hypokalemia

PURPOSE OF REVIEW

The aims of this article are to review the current controversies related to the use of thiazide diuretics as first-line treatment of hypertension and to discuss the causal roles for hyperuricemia and hypokalemia on the adverse consequences of thiazide usage.

RECENT FINDINGS

Thiazides significantly reduce morbidity and mortality in hypertensive subjects. There remains, however, debate about thiazide usage as first-line treatment of hypertension. This negative impact of thiazides may be partially attributed to the ability of thiazides to exacerbate features of metabolic syndrome or increase the risk for developing diabetes. Several clinical trials suggest that thiazide-induced hyperuricemia and hypokalemia may account for some of these negative effects. Thiazide treatment is also associated with a decline of renal function in spite of a lowering blood pressure. In this review, we discuss the clinical and experimental evidence supporting a potential role of hyperuricemia and hypokalemia on the development of renal injury and worsening of the metabolic syndrome.

SUMMARY

Hyperuricemia and hypokalemia may have pivotal roles in the exacerbation of the metabolic syndrome in response to thiazides. We propose that controlling serum uric acid and serum potassium could improve thiazide efficacy and also reduce its risk for inducing metabolic syndrome or diabetes.

Blood pressure drug therapy and electrolyte disturbances

Antihypertensive pharmacologic treatment may be associated with diverse disturbances of electrolyte homeostasis. These drug-induced disorders are relatively common, typically including hyponatraemia, hypokalaemia, hyperkalaemia, hypomagnesaemia, hypophosphataemia and hypercalcaemia. Diuretics, beta-blockers, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are particularly likely to cause these complications. Recognised risk factors include high-dosage regimens (especially diuretics), old age, diabetes and impairment of renal function. Strategies to prevent these adverse drug reactions involve careful consideration of risk factors and clinical and laboratory evaluation in the course of treatment.

Clinical effects of torasemide prolonged release in mild-to-moderate hypertension: a randomized noninferiority trial versus torasemide immediate release

The efficacy of a new torasemide prolonged release (PR) formulation to torasemide immediate release (IR) was compared in a randomized noninferiority double-blind trial. Patients with newly diagnosed mild-to-moderate hypertension or unresponsive or poor tolerability to previous antihypertensive monotherapy received 5 mg/day of torasemide-PR (n = 219) or torasemide-IR (n = 223) for 12 weeks (uptitration to 10 mg/day if no response at 4 or 8 weeks). Mean diastolic blood pressure (DBP) reduction in the torasemide-PR group (11.6 +/- 7.1 mmHg, 95% confidence interval [CI] 10.6-12.5) versus torasemide-IR (11.3 +/- 7.5 mmHg, 95% CI 10.2-12.3) met the noninferiority criterion of a nonsided 97.5% CI lower than the preestablished margin of 2 mmHg. A significantly higher percentage of patients in the torasemide-PR group achieved adequate BP control after 8 and 12 weeks. Ambulatory 24-h BP monitoring (ABPM) measurements in a subset of 100 patients showed greater daytime SBP reductions in the torasemide-PR group (128.4 +/- 9.9 mmHg vs. 133.5 +/- 10.4 mmHg, P < 0.05). Safety and tolerability of both formulations were similar.

Indapamide Decreases Plasma Adiponectin Concentration in Patients with Essential Hypertension

BACKGROUND/AIM

Adiponectin is an adipose tissue-specific protein with antiatherogenic and insulin-sensitizing properties. In patients with essential hypertension, plasma adiponectin concentrations are lower than in healthy subjects. Antihypertensive drugs do not uniformly influence components of the metabolic syndrome. Therefore, the aim of this study was to evaluate the influence of 6 months' monotherapy with different antihypertensive drugs on plasma adiponectin concentration in essential hypertension patients.

METHODS

Forty essential hypertension patients were randomized to receive enalapril, metoprolol, amlodipine or indapamide. Plasma concentrations of adiponectin, insulin, glucose and body fat content were estimated twice: before and after 6 months of antihypertensive monotherapy.

RESULTS

Plasma adiponectin concentration did not change significantly after enalapril (11.5 +/- 4.8 vs. 11.1 +/- 4.1 mg/l), metoprolol (10.2 +/- 4.2 vs. 9.8 +/- 4.5 mg/l), and amlodipine (9.0 +/- 6.0 vs. 8.5 +/- 5.4 mg/l) treatment. However, a significant decrease of plasma adiponectin concentration (from 11.6 +/- 4.6 to 10.2 +/- 4.2 mg/l, p = 0.047) was observed in patients treated with indapamide. Additionally in these patients, a significant increase of the HOMA-IR index was found (p = 0.021).

CONCLUSION

Treatment with indapamide was followed by a significant decrease of plasma adiponectin concentration. This may participate in the pathogenesis of carbohydrate metabolism disturbances often found in patients treated with thiazide-type diuretics.

Randomized, placebo-controlled trial of the effects of drospirenone-estradiol on blood pressure and potassium balance in hypertensive postmenopausal women receiving hydrochlorothiazide

OBJECTIVE

Drospirenone (DRSP), a spironolactone analog with aldosterone antagonist activity, is a novel progestogen developed for use as hormone therapy in postmenopausal women in combination with 17beta-estradiol (E2). DRSP/E2 lowers blood pressure when used alone in hypertensive postmenopausal women or when administered concomitantly with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. DRSP/E2 has not been studied in combination with the widely prescribed hydrochlorothiazide (HCTZ). We investigated the effects of 3 mg DRSP/1 mg E2 versus placebo on blood pressure and potassium balance when added to existing therapy with 25 mg HCTZ in postmenopausal women with established stage I hypertension.

DESIGN

This was a single-center, double-blind, randomized, placebo-controlled, two-treatment, two 4-week treatment period crossover study in 36 postmenopausal women with stage I hypertension maintained on 25 mg HCTZ. The endpoint was a change from baseline in systolic and diastolic blood pressures by 24-hour ambulatory blood pressure monitoring. Safety monitoring included serum potassium (mEq/L) and adverse events.

RESULTS

Mean systolic and diastolic blood pressures by 24-hour ambulatory blood pressure monitoring were reduced significantly, by -7.2 and -4.5 mm Hg, respectively, with DRSP/E2 as compared with placebo. The decrease in potassium with HCTZ was 0.2 mEq/L less with DRSP/E2 than placebo, suggesting a potassium-sparing effect. The most frequently observed adverse events with DRSP/E2 were vaginal bleeding and breast tenderness, which were attributable to the hormone therapy.

CONCLUSIONS

DRSP/E2 substantially lowers systolic and diastolic blood pressure when added to existing antihypertensive therapy with HCTZ in hypertensive postmenopausal women. In addition, DRSP/E2 has a potassium-sparing effect that counteracts HCTZ-induced potassium loss.

Adverse metabolic side effects of thiazides: implications for patients with calcium nephrolithiasis

PURPOSE

Thiazide use to prevent recurrent calcium nephrolithiasis is supported by randomized, controlled trials. Concerns regarding adverse metabolic effects of thiazides, which are also used to treat hypertension, have reemerged with analysis of the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial. The risks posed by thiazide induced hyperglycemia, hyperuricemia, hypokalemia and dyslipidemia may decrease the expected cardiovascular benefit of lowering blood pressure in hypertensive patients. Whether these side effects occur and are clinically significant in nonhypertensive patients with kidney stones treated with thiazides is unclear.

MATERIALS AND METHODS

A review of the literature was performed for randomized, controlled trials with thiazides for calcium nephrolithiasis. We sought data regarding metabolic effects in this population, including hyperglycemia, hyperuricemia, hypokalemia and dyslipidemia.

RESULTS

Nine randomized, controlled trials of thiazide treatment for kidney stones were included. Mean patient age was 42 years and followup was 2.6 years. Only 2 of the 9 studies measured glucose and lipid levels, which did not significantly change with treatment. Three studies measured serum potassium and 2 showed a significant decrease. Three of the 9 studies measured serum uric acid levels, which increased in all 3. None of the trials studied the development of diabetes mellitus or cardiovascular disease.

CONCLUSIONS

There is a lack of data on the metabolic effects of thiazides used to prevent recurrent calcium nephrolithiasis. It remains unclear if metabolic effects occur and increase the risk of cardiovascular disease in otherwise healthy patients with recurrent nephrolithiasis on thiazide prophylaxis. Further research is needed to elucidate other alternatives for the treatment of recurrent nephrolithiasis.

Rates and determinants of reinitiating antihypertensive therapy after prolonged stoppage: a population-based study

OBJECTIVE

To assess patterns of restarting antihypertensive drugs after a prolonged period of discontinuation.

METHODS

We conducted a retrospective cohort study among new users of blood pressure-lowering medication in the PHARMO database in The Netherlands, who had a period of at least 180 days without such medication. A multivariable Cox proportional hazard analysis was used to explore the baseline variables associated with reinitiating treatment. Case-crossover analysis was used to evaluate determinants of reinitiating treatment.

RESULTS

We identified 35,714 patients as initiating blood pressure-lowering treatment during the period 1 January 1999 to 30 June 2004. Of the 18,357 (51.4%) patients who discontinued blood pressure-lowering treatment, 19.3% restarted treatment within 1 year and 60.7% restarted within 6 years. With every additional year they had been on therapy, patients were more likely to restart [odds ratio (OR) = 1.38; 95% confidence interval (CI) = 1.34-1.42]. The case-crossover analysis revealed that hospitalization for cardiovascular disease (OR = 2.20; 95% CI = 1.84-2.63), as well as refilling of another cardiovascular medication (OR = 1.25; 95% CI = 1.11-1.40), were each independently associated with reinitiating treatment. Refilling non-cardiovascular medications was not associated with reinitiating treatment (OR = 1.03; 95% CI = 0.97-1.10).

CONCLUSION

Physicians should be aware that many patients have prolonged periods of discontinuation during the use of blood pressure-lowering medication, and that most of these patients will eventually resume therapy. Ongoing refilling other medications is not associated with reinitiating treatment. This suggests that, for some patients, the decision to discontinue may be drug specific rather than a behavioural characteristic applicable to all chronic treatments.