Update of Diuretics in the Treatment of Hypertension

Effect of Calcium Channel Blockers versus Diuretics for Hypertension

Background

Although calcium channel blockers (CCBs) are recognized as clinical first-line agents for the treatment of hypertension, their use in combination with diuretics in cardiovascular disease caused by hypertension remains controversial.

Methods

We searched the three major databases of the Cochrane Library, EMBASE, and PubMed for the terms “calcium channel blockers,” “thiazide diuretics,” “loop diuretics,” and “hypertension,” “randomized controlled trials” and “meta-analysis trials.” These terms were searched from January 1991 to October 2021.

Results

For the primary outcome, in 5 studies including 35,057 patients, there was no statistically significant difference in all-cause mortality with calcium channel blockers compared with diuretics (RR = 0.98, 95% CI 0.92–1.04, I² = 0). In four studies including 33,643 patients with major cardiovascular events, there was no statistically significant difference in major cardiovascular events with calcium channel blockers compared with diuretics (RR = 1.00, 95% CI 1.04–1.09, I² = 0).

Conclusion

There is no statistically significant difference between calcium channel blockers and diuretics in terms of cardiovascular clinical prognosis in hypertensive patients, but there are positive implications for clinical guidance, which need to be fully validated in new large randomized controlled trials.

HPTLC Method for the Ultrasensitive Detection of Triamterene in Plasma

A high-performance thin-layer chromatographic (HPTLC) method has developed for the selective detection of a diuretic drug, triamterene (TRIAM), in pure form, tablets and human plasma. The method was based on chromatographic separation of TRIAM using HPTLC plates, precoated with silica gel, and a mobile phase consisted of ethyl acetate: dimethylformamide: ammonia (7.0: 2.7: 0.3, by volume). The native fluorescence signal of TRIAM was detected at 440 nm and used to quantify TRIAM using the proposed method, improving the method sensitivity to ~250-folds in comparison to that reported in previous HPTLC studies. The developed method enabled the detection of TRIAM in pure drug and biological samples (human plasma) within linear concentrations ranged from 0.8 to 60 ng/band or 1.0 to 60 ng/band for pure drug and plasma samples, respectively. Furthermore, the method was validated according to the official guidelines to permit its applicability in quality control and clinical laboratories.

Water Homeostasis and Cell Volume Maintenance and Regulation

From early unicellular organisms that formed in salty water environments to complex organisms that live on land away from water, cells have had to protect a homeostatic internal environment favorable to the biochemical reactions necessary for life. In this chapter, we will outline what steps were necessary to conserve the water within our cells and how mechanisms have evolved to maintain and regulate our cellular and organismal volume. We will first examine whole body water homeostasis and the relationship between kidney function, regulation of blood pressure, and blood filtration in the process of producing urine. We will then discuss how the composition of the lipid-rich bilayer affects its permeability to water and salts, and how the cell uses this differential to drive physiological and biochemical cellular functions. The capacity to maintain cell volume is vital to epithelial transport, neurotransmission, cell cycle, apoptosis, and cell migration. Finally, we will wrap up the chapter by discussing in some detail specific channels, cotransporters, and exchangers that have evolved to facilitate the movement of cations and anions otherwise unable to cross the lipid-rich bilayer and that are involved in maintaining or regulating cell volume.

Effects of triple combination therapy with azilsartan/amlodipine/hydrochlorothiazide on office/home blood pressure: a randomized-controlled trial in Japanese essential hypertensive patients

OBJECTIVE

The efficacy and safety of triple therapy with azilsartan (AZI), amlodipine besylate (AML), and hydrochlorothiazide (HCTZ) compared with dual therapy with AZI/AML or HCTZ monotherapy were evaluated in Japanese essential hypertensive patients in a double-blinded manner.

PATIENTS AND METHODS

A total of 353 patients with office blood pressure (BP) of at least 150/95 mmHg were randomized to a 10-week treatment with AZI/AML/HCTZ 20/5/12.5 mg, AZI/AML/HCTZ 20/5/6.25 mg, AZI/AML 20/5 mg, HCTZ 12.5 mg, or HCTZ 6.25 mg.

RESULTS

The mean change from baseline in office diastolic/systolic BPs at week 10 was -25.9/-41.4, -24.9/-38.6, and -22.4/-34.5 mmHg in the AZI/AML/HCTZ 20/5/12.5 mg, AZI/AML/HCTZ 20/5/6.25 mg, and AZI/AML 20/5 mg groups, respectively. AZI/AML/HCTZ 20/5/12.5 mg led to a significantly greater reduction in diastolic and systolic BP than the dual therapy. In addition, the change in home diastolic BP measured with telemetry devices showed a significant difference between the two triple therapy groups. The incidences of adverse events except dizziness postural were similar among the treatment groups in the triple therapy groups.

CONCLUSION

Triple therapy with AZI/AML/HCTZ 20/5/12.5 mg shows a greater antihypertensive effect than the dual therapy and has acceptable safety profiles for Japanese essential hypertensive patients. It was also observed that home BP measurement by automated telemetry could detect changes in BP that were not detected in office BP measurement, although further investigation is needed.

A phase III, open-label, multicenter study to evaluate the safety and efficacy of long-term triple combination therapy with azilsartan, amlodipine, and hydrochlorothiazide in patients with essential hypertension

PURPOSE

Patients with essential hypertension who are receiving treatment with an angiotensin II receptor blocker and a calcium channel blocker often develop inadequate blood pressure (BP) control and require the addition of a diuretic. This study aimed to evaluate the long-term safety and efficacy of a triple combination therapy with 20 mg azilsartan (AZL), 5 mg amlodipine (AML) and 12.5 mg hydrochlorothiazide (HCTZ).

MATERIALS AND METHODS

The phase III, open-label, multicenter study (NCT02277691) comprised a 4-week run-in period and 52-week treatment period. Patients with inadequate BP control despite AZL/AML therapy (n = 341) received 4 weeks' treatment with AZL/AML (combination tablet) + HCTZ (tablet) and 4 weeks' treatment with AZL/AML/HCTZ (combination tablet) in a crossover manner, followed by AZL/AML/HCTZ (combination tablet) from Week 8 of the treatment period up to Week 52. The primary and secondary endpoints were long-term safety and BP (office and home), respectively.

RESULTS

Most adverse events (AEs) were mild or moderate in intensity, and no deaths or treatment-related serious AEs were reported. The triple therapy provided consistent BP-lowering effects in both office and home measurements.

CONCLUSIONS

The triple combination therapy with AZL/AML/HCTZ was well tolerated and effective for 52 weeks in Japanese patients with essential hypertension.

Combination therapy with lercanidipine and enalapril in the management of the hypertensive patient: an update of the evidence

Hypertension is an important risk factor for premature death as it increases the probability of stroke, myocardial infarction, and heart failure. Antihypertensive drugs can decrease cardiovascular (CV) morbidity and mortality. The majority of hypertensive patients need more than one antihypertensive agent to attain blood pressure (BP) targets. Monotherapy can effectively reduce BP only in 20%–40% of patients. Multiple mechanisms including increased peripheral vascular resistance, increased cardiac work, and hypervolemia are involved in the pathogenesis of hypertension. Targeting multiple pathways may more potently reduce BP. Increasing the dose of a single agent in many cases does not provide the expected BP-lowering effect because the underlying mechanism of the BP increase is either different or already corrected with the lower dose. Moreover, drugs acting on different pathways may have synergistic effects and thus better control hypertension. It is well known that diuretics enhance the actions of renin–angiotensin aldosterone system and activate it as a feedback to the reduced circulated blood volume. The addition of a renin–angiotensin aldosterone system blocker to a diuretic may more effectively reduce BP because the system is upregulated. Reducing the maximal dose of an agent may also reduce possible side effects if they are dose dependent. The increased prevalence of peripheral edema with higher doses of calcium channel blockers (CCBs) is reduced when renin–angiotensin aldosterone system blockers are added to CCBs through vein dilation. The effectiveness of the combination of enalapril with lercanidipine in reducing BP, the safety profile, and the use of the combination of angiotensin-converting enzyme inhibitors with CCBs in clinical trials with excellent CV hard end point outcomes make this combination a promising therapy in the treatment of hypertension.

Natriuresis and blood pressure reduction in hypertensive patients with diabetes mellitus: the NESTOR study

The antihypertensive effect of indapamide has never been clearly understood, particularly in hypertensive patients with diabetes mellitus. A total of 565 patients were randomly selected to receive either indapamide 1.5 mg or enalapril 10 mg daily for 12 months. Brachial blood pressure (BP) and plasma and urinary electrolytes were measured at baseline and at the end of follow-up. Sodium and potassium levels and excretion rates were measured in overnight urine collections. After 12 months' treatment, similar significant reductions were observed in systolic and diastolic BP and pulse pressure levels in both treatment arms (P < .001). However, age, body mass index, diabetes duration, and plasma sodium reductions were shown to be major, independent factors influencing BP reduction with indapamide, but not with enalapril. Regression coefficients were positive for age and plasma sodium reductions (P ≤ .009) but negative for body mass index and diabetes duration (P ≤ .008). Similar findings were observed for pulse pressure. These results were more notable in elderly patients, did not differ regardless of whether BP reduction was measured in absolute or percent values, and were associated with increased sodium and potassium excretion rates.Indapamide is more effective than enalapril at reducing BP in elderly diabetic hypertensives with marked sodium retention.

Use of combination antihypertensive therapy initiation in older Americans without prevalent cardiovascular disease

OBJECTIVES

To describe new users of antihypertensive medications and identify predictors of combination therapy initiation in older Americans.

DESIGN

Retrospective observational cohort study.

SETTING

Population-based study using U.S. Medicare fee-for-service healthcare claims (2007-2010).

PARTICIPANTS

Medicare beneficiaries aged 65 and older with no recent diagnoses, procedures, or medications for cardiovascular disease who newly initiated an antihypertensive therapy (n = 275,493; 210,605 initiated monotherapy, 64,888 initiated combination therapy).

MEASUREMENTS

Multivariable Poisson regression was used to assess factors associated with initiation of combination therapy versus monotherapy, including participant characteristics, prescriber characteristics, and participant encounters with the healthcare system.

RESULTS

Initiation of combination therapy increased from 21.9% in 2007 to 24.7% in 2010. The most frequently initiated combinations were angiotensin-converting enzyme inhibitors with thiazide (29.7%) and angiotensin II receptor antagonists with thiazide (18.7%). Blacks (prevalence ratio (PR) = 1.48, 95% confidence interval (CI) = 1.45-1.51 vs. whites), individuals seeing a generalist (PR = 1.10, 95% CI = 1.07-1.14), individuals seeing more than one doctor (PR = 3.38, 95% CI = 3.33-3.44), and participants with no pharmacy claims in the previous 6 months (PR = 1.34, 95% CI = 1.30-1.37 vs. ≥3 unique drug classes) were more likely to initiate combination therapy, whereas those who had more outpatient visits in the previous 12 months were less likely to initiate combination therapy (per five visits, PR = 0.82, 95% CI = 0.80-0.83).

CONCLUSION

Nearly one in four new users of antihypertensive medications aged 65 and older started treatment with combination therapy. Blacks, individuals living in the south, and those with fewer outpatient physician office visits were more likely to initiate combination therapy. Further research is needed to determine whether this approach to managing hypertension is being well targeted to individuals who will require combination treatment.

Which thiazide to choose as add-on therapy for hypertension?

Combined therapy is required in the majority of patients with hypertension to achieve blood pressure (BP) targets. Although different antihypertensive drugs can be combined, not all combinations are equally effective and safe. In this context, the combination of a renin angiotensin system inhibitor with a diuretic, usually a thiazide, particularly hydrochlorothiazide (HCTZ) or thiazide-like diuretics, such as chlorthalidone or indapamide, is recommended. However, not all diuretics are equal. Although HCTZ, chlorthalidone, and indapamide as add-on therapy effectively reduce BP levels, the majority of studies have obtained greater BP reductions with chlorthalidone or indapamide than with HCTZ. Moreover, there are data showing benefits with chlorthalidone or indapamide beyond BP. Thus, chlorthalidone seems to have pleiotropic effects beyond BP reduction. Moreover, compared with placebo, chlorthalidone has small effects on fasting glucose and total cholesterol, and compared with HCTZ, chlorthalidone achieves significantly lower total cholesterol and low-density lipoprotein cholesterol levels. Similarly, indapamide has demonstrated no negative impact on glucose or lipid metabolism. More importantly, although head-to-head clinical trials comparing the effects of indapamide or chlorthalidone with HCTZ are not available, indirect comparisons and post hoc analyses suggest that the use of chlorthalidone or indapamide is associated with a reduction in cardiovascular events. Despite this, the most frequent diuretic used in clinical practice as add-on therapy for hypertension is HCTZ. The purpose of this review is to update the published data on the efficacy and safety of HCTZ, chlorthalidone, and indapamide as add-on therapy in patients with hypertension.

Assessment of urinary betaine as a marker of diabetes mellitus in cardiovascular patients

Abnormal urinary excretion of betaine has been demonstrated in patients with diabetes or metabolic syndrome. We aimed to identify the main predictors of excretion in cardiovascular patients and to make initial assessment of its feasibility as a risk marker of future diabetes development. We used data from 2396 patients participating in the Western Norway B-vitamin Intervention Trial, who delivered urine and blood samples at baseline, and in the majority at two visits during follow-up of median 39 months. Betaine in urine and plasma were measured by liquid-chromatography-tandem mass spectrometry. The strongest determinants of urinary betaine excretion by multiple regression were diabetes mellitus, age and estimated glomerular filtration rate; all p<0.001. Patients with diabetes mellitus (n = 264) had a median excretion more than three times higher than those without. We found a distinct non-linear association between urinary betaine excretion and glycated hemoglobin, with a break-point at 6.5%, and glycated hemoglobin was the strongest determinant of betaine excretion in patients with diabetes mellitus. The discriminatory power for diabetes mellitus corresponded to an area under the curve by receiver-operating characteristics of 0.82, and betaine excretion had a coefficient of reliability of 0.73. We also found a significant, independent log-linear relation between baseline betaine excretion and the risk of developing new diabetes during follow-up. The good discriminatory power for diabetes, high test-retest stability and independent association with future risk of new diabetes should motivate further investigation on the role of betaine excretion in risk assessment and long-term follow-up of diabetes mellitus.

Diuretics with carbonic anhydrase inhibitory action: a patent and literature review (2005 - 2013)

INTRODUCTION

The benzothiadiazines and high ceiling diuretics (hydrochlorothiazide, hydroflumethiazide, quinethazone, metolazone, chlorthalidone, indapamide, furosemide and bumetanide) contain primary sulfamoyl moieties acting as zinc-binding groups in the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). These drugs are widely used clinically and were recently shown to weakly inhibit isoforms CA I and II, but to possess stronger activity against isoforms involved in other important pathologies, for example, obesity, cancer, epilepsy and hypertension.

AREAS COVERED

The class of clinically used diuretics, with CA inhibitory properties, is the main topic of the review. A patent literature review covering the period from 2005 to 2013 is presented.

EXPERT OPINION

This section presents an overview of the patent literature in the sulfonamide diuretic field. Most of the patents deal with the combination of diuretic sulfonamide CA inhibitors with other agents useful in the management of cardiovascular diseases and obesity. Such combinations exert a better therapeutic activity compared to similar diuretics that do not inhibit CAs, raising the question of the polypharmacological and drug repositioning effects of these old drugs. These effects seem to be due to the potent inhibition of such drugs against CA isoforms present in kidneys and blood vessels, which explain both the blood pressure lowering effects as well as organ-protective activity of the drugs. An explanation of these data is provided by the fact that inhibition of the renal CAs leads to a large increase of the nitrite excretion in urine, suggesting that renal CAs are involved in nitrite reabsorption in humans. Important lessons for the drug design of sulfonamide CA inhibitors (CAIs) can be drawn from these data.

Long-term efficacy and tolerability of a fixed-dose combination of antihypertensive agents: an open-label surveillance study in China

BACKGROUND

A fixed-dose combination (FDC) of four compounds, hydrochlorothiazide 12.5 mg, triamterene 12.5 mg, dihydralazine 12.5 mg and reserpine 0.1 mg (HTDR), is widely used as an antihypertensive treatment in China. Although HTDR has been used in China for more than 30 years, there have been few comprehensive evaluations of this treatment.

OBJECTIVE

The aim of this study was to investigate the long-term efficacy and tolerability of HTDR in Chinese patients with essential hypertension.

METHODS

This was a 36-month, community-based, open-label surveillance study, conducted in the Huangpu District (Shanghai, China). The study was based in local primary healthcare settings. Subjects were recruited if they had essential hypertension, were aged ≥35 years at the time of enrolment, were expected to remain in the area for 3 years, and were able to provide informed consent. Patients who had secondary hypertension, myocardial infarction or stroke within 6 months of screening, impaired renal or hepatic function, history of cardiomyopathy or chronic heart failure, or were pregnant or lactating were excluded. HTDR was administered as one or two tablets per day in the morning. If necessary, additional hydrochlorothiazide was added. Blood pressure (BP) was measured at baseline and throughout the 36-month surveillance period every 3 months. Biochemical indicators (e.g. fasting blood glucose, plasma lipid parameters, plasma sodium and potassium, plasma uric acid and serum creatinine) were also measured, and adverse events were noted. BP reductions and the rate at which patients achieved BP targets (systolic BP [SBP] <140 mmHg and diastolic BP [DBP] <90 mmHg) throughout the period were determined. Subgroup analyses by sex and age were also conducted.

RESULTS

A total of 1529 patients (550 male, 979 female; mean age 65.7 years) entered the study. After the 36-month treatment period, 93.1% of patients had achieved the SBP target, 97.9% had achieved the DBP target, and 92.1% had achieved both. The mean decreases in SBP and DBP were 15.3 mmHg and 9.9 mmHg, respectively. Overall, 127 adverse events in 119 patients (7.8%) occurred during the follow-up period, most of which were mild to moderate. Plasma lipid profiles were improved after 24 months of treatment. In addition, a significant increase in plasma potassium and a significant reduction in plasma uric acid were seen.

CONCLUSION

HTDR was found to have good long-term efficacy and tolerability in Chinese patients with essential hypertension.

The central mechanism underlying hypertension: a review of the roles of sodium ions, epithelial sodium channels, the renin-angiotensin-aldosterone system, oxidative stress and endogenous digitalis in the brain

The central nervous system has a key role in regulating the circulatory system by modulating the sympathetic and parasympathetic nervous systems, pituitary hormone release, and the baroreceptor reflex. Digoxin- and ouabain-like immunoreactive materials were found >20 years ago in the hypothalamic nuclei. These factors appeared to localize to the paraventricular and supraoptic nuclei and the nerve fibers at the circumventricular organs and supposed to affect electrolyte balance and blood pressure. The turnover rate of these materials increases with increasing sodium intake. As intracerebroventricular injection of ouabain increases blood pressure via sympathetic activation, an endogenous digitalis-like factor (EDLF) was thought to regulate cardiovascular system-related functions in the brain, particularly after sodium loading. Experiments conducted mainly in rats revealed that the mechanism of action of ouabain in the brain involves sodium ions, epithelial sodium channels (ENaCs) and the renin-angiotensin-aldosterone system (RAAS), all of which are affected by sodium loading. Rats fed a high-sodium diet develop elevated sodium levels in their cerebrospinal fluid, which activates ENaCs. Activated ENaCs and/or increased intracellular sodium in neurons activate the RAAS; this releases EDLF in the brain, activating the sympathetic nervous system. The RAAS promotes oxidative stress in the brain, further activating the RAAS and augmenting sympathetic outflow. Angiotensin II and aldosterone of peripheral origin act in the brain to activate this cascade, increasing sympathetic outflow and leading to hypertension. Thus, the brain Na(+)-ENaC-RAAS-EDLF axis activates sympathetic outflow and has a crucial role in essential and secondary hypertension. This report provides an overview of the central mechanism underlying hypertension and discusses the use of antihypertensive agents.

Isolation and cloning of the K+-independent, ouabain-insensitive Na+-ATPase

Primary Na+ transport has been essentially attributed to Na+/K+ pump. However, there are functional and biochemical evidences that suggest the existence of a K+-independent, ouabain-insensitive Na+ pump, associated to a Na+-ATPase with similar characteristics, located at basolateral plasma membrane of epithelial cells. Herein, membrane protein complex associated with this Na+-ATPase was identified. Basolateral membranes from guinea-pig enterocytes were solubilized with polyoxyethylene-9-lauryl ether and Na+-ATPase was purified by concanavalin A affinity and ion exchange chromatographies. Purified enzyme preserves its native biochemical characteristics: Mg2+ dependence, specific Na+ stimulation, K+ independence, ouabain insensitivity and inhibition by furosemide (IC50: 0.5 mM) and vanadate (IC50: 9.1 μM). IgY antibodies against purified Na+-ATPase did not recognize Na+/K+-ATPase and vice versa. Analysis of purified Na+-ATPase by SDS-PAGE and 2D-electrophoresis showed that is constituted by two subunits: 90 (α) and 50 (β) kDa. Tandem mass spectrometry of α-subunit identified three peptides, also present in most Na+/K+-ATPase isoforms, which were used to design primers for cloning both ATPases by PCR from guinea-pig intestinal epithelial cells. A cDNA fragment of 1148 bp (atna) was cloned, in addition to Na+/K+-ATPase α1-isoform cDNA (1283 bp). In MDCK cells, which constitutively express Na+-ATPase, silencing of atna mRNA specifically suppressed Na+-ATPase α-subunit and ouabain-insensitive Na+-ATPase activity, demonstrating that atna transcript is linked to this enzyme. Guinea-pig atna mRNA sequence (2787 bp) was completed using RLM-RACE. It encodes a protein of 811 amino acids (88.9 kDa) with the nine structural motifs of P-type ATPases. It has 64% identity and 72% homology with guinea-pig Na+/K+-ATPase α1-isoform. These structural and biochemical evidences identify the K+-independent, ouabain-insensitive Na+-ATPase as a unique P-type ATPase.

Hyponatremia in heart failure: revisiting pathophysiology and therapeutic strategies

Hyponatremia is frequently encountered in patients with heart failure (HF), and its association with adverse outcomes is well-established in this population. While hyponatremia is an independent marker for severity of HF, it is not certain whether it has a causal impact on the progression of the disease. There are no universally accepted consensus guidelines regarding therapeutic strategies for HF-associated hyponatremia and volume overload; current societal guidelines do not address management of this complication. Whereas thiazide diuretics are known to induce or worsen hyponatremia in this setting through a number of mechanisms, loop diuretics can be considered a readily available first-line pharmacologic therapy. Consistent with pathophysiology of the disease and mechanisms of action of loop diuretics, available clinical evidence supports such an approach provided that patients can be closely monitored. Use of vasopressin receptor antagonists is an emerging therapeutic strategy in this setting, and the efficacy of these agents has so far been shown in a number of clinical studies. These agents can be reserved for patients with HF in whom initial appropriate loop diuretic therapy fails to improve serum sodium levels.

The small molecule phenamil is a modulator of adipocyte differentiation and PPARgamma expression

We previously described the use of a cell-based screening approach to identify small molecules that regulate adipocyte differentiation. Here we identify the amiloride derivative phenamil as an adipogenic compound. Phenamil acutely induces expression of the key transcription factor of adipogenesis, peroxisome proliferator-activated receptor γ (PPARγ) and, consequently, promotes the differentiation of multiple preadipocyte cell lines, including 3T3-L1 and F442A. Interestingly, the adipogenic action of phenamil is distinct from and additive with both PPARγ ligands and the previously identified adipogenic small molecule harmine. To identify signaling pathways mediating phenamil's effects, we performed transcriptional profiling of 3T3-F442A preadipocytes. ETS variant 4 (ETV4) was identified as a gene rapidly induced by phenamil but not by other adipogenic small molecules or PPARγ agonists. Transient expression of ETV4 in preadipocytes enhances the expression of PPARγ. Stable overexpression of ETV4 promotes expression of PPARγ and its downstream target genes and enhances morphological differentiation. Finally, knockdown of PPARγ expression by shRNA blocks the effects of phenamil on adipocyte differentiation and gene expression, but it does not block phenamil induction of ETV4, which suggests that ETV4 acts upstream of PPARγ in differentiation processes. These results identify a phenamil as new small molecule tool for the probing of adipocyte differentiation that acts, at least in part, through induction of ETV4 expression.

Clinical approach in treatment of resistant hypertension

Resistant hypertension, defined as failure to achieve target blood pressure despite the use of optimal or maximum doses of at least 3 agents, one of which is a diuretic, or requiring 4 or more medications to achieve blood pressure goal, is likely to affect up to 20% of all patients with hypertension. Apparent resistant hypertension may be caused by medication nonadherence, substances that either interfere with antihypertensive mediations or cause blood pressure elevation, and under- or inappropriate medication treatment. Certain patient characteristics are associated with the presence of resistant hypertension and include chronic kidney disease, diabetes, obesity, and presence of end-organ damage (microalbuminuria, retinopathy, left-ventricular hypertrophy). Secondary causes of resistant hypertension are not uncommon and include obstructive sleep apnea, chronic kidney disease, primary aldosteronism, renal artery stenosis, pheochromocytoma, and Cushing's disease. Initial medication management usually includes adding or increasing the dose of a diuretic, which is effective in lowering the blood pressure of a large number of patients with resistant hypertension. Additional management options include maximizing lifestyle modification, combination therapy of antihypertensive agents depending on individual patient characteristics, adding less-commonly used fourth- or fifth-line antihypertensive agents, and referral to a hypertension specialist.

The small molecule phenamil induces osteoblast differentiation and mineralization

Stimulation of osteoblast differentiation from mesenchymal stem cells is a potential strategy for bone repair. Bone morphogenetic proteins (BMPs) that induce osteoblastic differentiation have been successfully used in humans to treat fractures. Here we outline a new approach to the stimulation of osteoblast differentiation using small molecules that stimulate BMP activity. We have identified the amiloride derivative phenamil as a stimulator of osteoblast differentiation and mineralization. Remarkably, phenamil acts cooperatively with BMPs to induce the expression of BMP target genes, osteogenic markers, and matrix mineralization in both mesenchymal stem cell lines and calvarial organ cultures. Transcriptional profiling of cells treated with phenamil led to the identification of tribbles homolog 3 (Trb3) as a mediator of its effects. Trb3 is induced by phenamil selectively in cells with osteoblastic potential. Both Trb3 and phenamil stabilize the expression of SMAD, the critical transcription factor in BMP signaling, by promoting the degradation of SMAD ubiquitin regulatory factor 1. Small interfering RNA-mediated knockdown of Trb3 blunts the effects of phenamil on BMP signaling and osteogenesis. Thus, phenamil induces osteogenic differentiation, at least in part, through Trb3-dependent promotion of BMP action. The synergistic use of small molecules such as phenamil along with BMPs may provide new strategies for the promotion of bone healing.

Complementary mechanisms of angiotensin receptor blockers and calcium channel blockers in managing hypertension

Hypertension affects approximately 73 million individuals in the United States. Clinical studies have shown that antihypertensive therapy can reduce blood pressure (BP) and the risk of cardiovascular events. However, the majority of patients with hypertension do not achieve the recommended BP goal of < 140/90 mm Hg (or < 130/80 mm Hg for patients with diabetes) with antihypertensive monotherapy, and require therapy with 2 or more antihypertensive agents. Combination therapy utilizes antihypertensive agents from different drug classes, which act via distinct pharmacologic mechanisms to improve overall efficacy and tolerability. Although combination therapy is superior to monotherapy in achieving BP goals across the entire spectrum of hypertension, the proportion of patients achieving the recommended BP goal can be further improved by the use of new antihypertensive drug combinations. The beneficial antihypertensive characteristics of both angiotensin receptor blockers and calcium channel blockers suggest that combining these classes may result in a highly efficacious antihypertensive therapy with regard to both activity and safety when used as a fixed-dose combination. In particular, a fixed-dose combination of olmesartan medoxomil plus amlodipine besylate has been demonstrated to be an efficacious antihypertensive combination due in part to the benefits associated with each of these agents within their respective drug classes.

Efficacy and Safety of Valsartan/Hydrochlorothiazide Fixed-dose Combination Compared with Amlodipine Monotherapy as First-line Therapy for Mild to Moderate Hypertension

This double-blind, active- and randomized-controlled study compared the efficacy and safety of a fixed-dose combination of valsartan/hydrochlorothiazide 80 mg/12.5 mg once daily ( n = 32) with amlodipine monotherapy 5 mg once daily ( n = 33) for 8 weeks in patients with mild to moderate hypertension. Non-inferiority of valsartan/hydrochlorothiazide to amlodipine was demonstrated by comparable reductions in sitting systolic blood pressure (SBP), sitting diastolic blood pressure (DBP), and daytime, night-time and 24-h SBP and DBP on ambulatory blood pressure monitoring. Between-group comparisons of adverse events and changes in laboratory parameters did not reach statistical significance, except for uric acid which showed a significant increase in the valsartan/hydrochlorothiazide group compared with the amlodipine group, but was still below the laboratory's upper limit of normal. In conclusion, the use of the fixed-dose combination of valsartan/hydrochlorothiazide 80 mg/12.5 mg once daily as a starting regimen in patients with mild to moderate hypertension was shown to have non-inferior efficacy and comparable safety for daily practice compared with amlodipine 5 mg once daily monotherapy.

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.

Results of increasing doses of hydrochlorothiazide in combination with an angiotensin receptor blocker in patients with uncontrolled hypertension

This study examined the effects of increasing the thiazide diuretic dose in a fixed-dose ARB/diuretic combination in patients with uncontrolled hypertension despite 6 weeks' open-label treatment with the ARB/diuretic combination, telmisartan 80 mg/hydrochlorothiazide 12.5 mg (T80/H12.5). 713 patients with trough seated DBP =90 mmHg were then randomized to 8 weeks' double-blind treatment with telmisartan 80 mg and an increased dose of 25 mg of hydrochlorothiazide (T80/H25) or T80/H12.5. Adjusted mean seated DBP changes from baselines of 95.3 (T80/H25) and 95.0 mmHg (T80/H12.5) were -7.1 and --5.5 mmHg (difference: 1.6 mm Hg), respectively (P=.0012). Changes in systolic blood pressure from 147.9 mmHg (T80/H25) and 147.4 mmHg (T80/H12.5) were -9.8 and -7.1 mmHg (difference: 2.7 mm Hg) (P=.0003). Adverse events occurred in 31.5% (T80/H25) and 29.6% (T80/H12.5), with serious events in 1.4% and 0.8%, respectively. Hypokalemia was rare. These results show that higher-dose thiazide diuretic in combination with T80 in patients with hypertension uncontrolled by T80/H12.5 provides additional blood pressure reductions and is well tolerated.

Hospital Pharmacy Pulse - Recent Publications on Medications and Pharmacy

Hospital Pharmacy presents this feature to keep pharmacists abreast of new publications in the medical/pharmacy literature. Articles of interest will be abstracted monthly regarding a broad scope of topics. Suggestions or comments may be addressed to: Jacyntha Sterling, Drug Information Specialist at Saint Francis Hospital, 6161 S Yale Ave., Tulsa, OK 74136 or e-mail: jasterling@saintfrancis.com .