Coadministration of thiazides increases the efficacy of loop diuretics even in patients with advanced renal failure

Effectiveness of thiazide and thiazide-like diuretics in advanced chronic kidney disease: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Thiazide diuretics are first-line drugs for the treatment of hypertension, but hypertension treatment guidelines have systematically discouraged their use in patients with advanced chronic kidney disease (CKD). For the first time, a systematic review and random-effects meta-analysis were performed to assess the effectiveness of thiazides and thiazide-like diuretics to treat hypertension in patients with stages 3b, 4, and 5 CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A systematic review and random-effects meta-analysis that included a literature search using the following databases were performed: MEDLINE through PubMed, Cochrane Database of Systematic Reviews (CDSR) and Cochrane Central Register of Controlled Trials (CENTRAL) through the Cochrane Library, Embase, and ISI - Web of Science (all databases). Prospective studies that evaluated the effectiveness of thiazide and thiazide-like diuretics in individuals with a GFR < 45 mL/min/1.73 m² were included.

RESULTS

Five clinical trials, totaling 214 participants, were included, and the mean GFR ranged from 13.0 ± 5.9 mL/min/1.73 m² to 26.8 ± 8.8 mL/min/1.73 m². There was evidence of a reduction in mean blood pressure and in GFR, as well as in fractional sodium excretion and fractional chloride excretion.

CONCLUSION

Thiazide and thiazide-like diuretics seem to maintain their effectiveness in lowering blood pressure in patients with advanced chronic kidney disease. These findings should spur new prospective randomized trials and spark discussions, particularly about upcoming hypertension guidelines.

Effects of Triamterene in Hospitalized Patients with Heart Failure and Diuretic Resistance: A Randomized Clinical Trial

Due to the potential benefits of triamterene in diuretic resistance, this study was performed to assess whether triamterene add-on to the standard treatment of heart failure (HF)-related diuretic resistance improves outcomes. A randomized clinical trial was performed on 45 hospitalized patients with HF with reduced ejection fraction who had diuretic resistance. Patients were randomized to receive either triamterene 50 mg plus hydrochlorothiazide 25 mg (n = 23) or hydrochlorothiazide 50 mg alone (n = 22) until hospital discharge. The primary outcomes were changes in weight and fluid input-to-output ratio. Secondary outcomes were respiratory rate, hospitalization duration, serum sodium and potassium, estimated glomerular filtration rate, creatinine, and blood urea nitrogen levels during the study period. The mean (standard deviation) of weight changes was not significantly different in the intervention and the control groups (-6.3 [4.8] vs -4.8 [2.4] kg, respectively; P = .1). No significant differences were shown in input-to-output changes between the 2 groups (208.0 [243.4] in the intervention and 600.2 [250.3] in the control group; P = .4). Although the respiratory rate of triamterene-treated patients decreased, the difference did not reach statistical significance (P = .2). Other secondary outcomes were also similar in both groups. This study did not support the use of triamterene as an add-on therapy for patients with HF-related diuretic resistance.

Underdiagnosed CKD in Geriatric Trauma Patients and Potent Prevention of Renal Impairment from Polypharmacy Risks through Individual Pharmacotherapy Management (IPM-III)

The aging global patient population with multimorbidity and concomitant polypharmacy is at increased risk for acute and chronic kidney disease, particularly with severe additional disease states or invasive surgical procedures. Because from the expertise of more than 58,600 self-reviewed medications, adverse drug reactions, drug interactions, inadequate dosing, and contraindications all proved to cause or exacerbate the worsening of renal function, we analyzed the association of an electronic patient record- and Summaries of Product Characteristics (SmPCs)-based comprehensive individual pharmacotherapy management (IPM) in the setting of 14 daily interdisciplinary patient visits with the outcome: further renal impairment with reduction of eGFR ≥ 20 mL/min (redGFR) in hospitalized trauma patients ≥ 70 years of age. The retrospective clinical study of 404 trauma patients comparing the historical control group (CG) before IPM with the IPM intervention group (IG) revealed a group-match in terms of potential confounders such as age, sex, BMI, arterial hypertension, diabetes mellitus, and injury patterns. Preexisting chronic kidney disease (CKD) > stage 2 diagnosed as eGFR < 60 mL/min/1.73 m² on hospital admission was 42% in the CG versus 50% in the IG, although in each group only less than 50% of this was coded as an ICD diagnosis in the patients' discharge letters (19% in CG and 21% in IG). IPM revealed an absolute risk reduction in redGFR of 5.5% (11 of 199 CG patients) to 0% in the IPM visit IG, a relative risk reduction of 100%, NNT 18, indicating high efficacy of IPM and benefit in improving outcomes. There even remained an additive superimposed significant association that included patients in the IPM group before/beyond the 14 daily IPM interventions, with a relative redGFR risk reduction of 0.55 (55%) to 2.5% (5 of 204 patients), OR 0.48 [95% CI 0.438-0.538] (p < 0.001). Bacteriuria, loop diuretics, allopurinol, eGFR ≥ 60 mL/min/1.73 m², eGFR < 60 mL/min/1.73 m², and CKD 3b were significantly associated with redGFR; of the latter, 10.5% developed redGFR. Further multivariable regression analysis adjusting for these and established risk factors revealed an additive, superimposed IPM effect on redGFR with an OR 0.238 [95% CI 0.06-0.91], relative risk reduction of 76.2%, regression coefficient -1.437 including patients not yet visited in the IPM period. As consequences of the IPM procedure, the IG differed from the CG by a significant reduction of NSAIDs (p < 0.001), HCT (p = 0.028) and Würzburger pain drip (p < 0.001), and significantly increased prescription rate of antibiotics (p = 0.004). In conclusion, (1) more than 50% of CKD in geriatric patients was not pre-recognized and underdiagnosed, and (2) the electronic patient records-based IPM interdisciplinary networking strategy was associated with effective prevention of further periinterventional renal impairment and requires obligatory implementation in all elderly patients to urgently improve patient and drug safety.

Hypertension as Cardiovascular Risk Factor in Chronic Kidney Disease

Hypertension is the leading modifiable cause of premature death and hence one of the global targets of World Health Organization for prevention. Hypertension also affects the great majority of patients with chronic kidney disease (CKD). Both hypertension and CKD are intrinsically related, as hypertension is a strong determinant of worse renal and cardiovascular outcomes and renal function decline aggravates hypertension. This bidirectional relationship is well documented by the high prevalence of hypertension across CKD stages and the dual benefits of effective antihypertensive treatments on renal and cardiovascular risk reduction. Achieving an optimal blood pressure (BP) target is mandatory and requires several pharmacological and lifestyle measures. However, it also requires a correct diagnosis based on reliable BP measurements (eg, 24-hour ambulatory BP monitoring, home BP), especially for populations like patients with CKD where reduced or reverse dipping patterns or masked and resistant hypertension are frequent and associated with a poor cardiovascular and renal prognosis. Even after achieving BP targets, which remain debated in CKD, the residual cardiovascular risk remains high. Current antihypertensive options have been enriched with novel agents that enable to lower the existing renal and cardiovascular risks, such as SGLT2 (sodium-glucose cotransporter-2) inhibitors and novel nonsteroidal mineralocorticoid receptor antagonists. Although their beneficial effects may be driven mostly from actions beyond BP control, recent evidence underline potential improvements on abnormal 24-hour BP phenotypes such as nondipping. Other promising novelties are still to come for the management of hypertension in CKD. In the present review, we shall discuss the existing evidence of hypertension as a cardiovascular risk factor in CKD, the importance of identifying hypertension phenotypes among patients with CKD, and the traditional and novel aspects of the management of hypertensives with CKD.

The Use of Thiazide Diuretics for the Treatment of Hypertension in Patients With Advanced Chronic Kidney Disease

The use of thiazide diuretics for the treatment of hypertension in patients with advance chronic kidney disease. Thiazides have been recommended as the first-line for the treatment of hypertension, yet their use has been discouraged in advanced chronic kidney disease (CKD), as they are suggested to be ineffective in advanced CKD. Recent data suggest that thiazide diuretics may be beneficial blood pressure control in addition to natriuresis in existing CKD. This review discusses the commercially available thiazides with a focus on thiazide pharmacology, most common adverse effects, clinical uses of thiazide diuretic, and the evidence for efficacy of thiazide use in advanced CKD.

Interplay of Breast Cancer Resistance Protein (Bcrp/Abcg2), Sex, and Fed State in Oral Pharmacokinetic Variability of Furosemide in Rats

Poor and variable oral bioavailability of furosemide (FUR) presents critical challenges in pharmacotherapy. We investigated the interplay of breast cancer resistance protein (Bcrp)-mediated transport, sex, and fed state on FUR pharmacokinetics (PK) in rats. A crossover PK study of FUR (5 mg/kg, oral) was performed in Sprague-Dawley rats (3 males and 3 females), alone or with a Bcrp inhibitor, novobiocin (NOV) (20 mg/kg, oral), in both fed and fasted states. Co-administration of NOV significantly increased FUR extent (AUC) and rate (C_max) of exposure by more than two-fold, which indicates efficient Bcrp inhibition in the intestine. The female rats showed two-fold higher AUC and C_max, and two-fold lower renal clearance of FUR compared to the male rats. The latter was correlated with higher renal abundance of Bcrp and organic anion transporters (Oats) in the male rats compared to age-matched female rats. These findings suggest that the PK of Bcrp and/or Oat substrates could be sex-dependent in rats. Moreover, allometric scaling of rat PK and toxicological data of Bcrp substrates should consider species and sex differences in Bcrp and Oat abundance in the kidney. Considering that Bcrp is abundant in the intestine of rats and humans, a prospective clinical study is warranted to evaluate the effect of Bcrp inhibition on FUR PK. The potential confounding effect of the Bcrp transporter should be considered when FUR is used as a clinical probe of renal organic anion transporter-mediated drug-drug interactions. Unlike human data, no food-effect was observed on FUR PK in rats.

Use of Thiazides to Treat Hypertension and Advanced CKD

PURPOSE OF REVIEW

Hypertension is often difficult to control in patients with CKD as manifested by suboptimal control rates in this population. Use of thiazides in CKD patients has been limited as these agents are thought to be ineffective in reducing blood pressure in people with advanced CKD. This review summarizes recent studies impacting indications and safety of use of thiazide in patients with CKD and discusses the mechanism of how thiazides reduce blood pressure.

RECENT FINDINGS

Chlorthalidone reduces blood pressure compared to placebo in patients with advanced CKD, challenging the belief that thiazide diuretics lose efficacy at lower levels of GFR. Recent clinical trial data indicate that thiazides are effective in patients with advanced kidney disease for blood pressure lowering. However, monitoring of electrolytes and kidney function is important to ensure patient safety when prescribing these agents in patients with CKD.

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.

Thiazide diuretics are back in CKD: the case of chlorthalidone

Sodium and volume excess is the fundamental risk factor underlying hypertension in chronic kidney disease (CKD) patients, who represent the prototypical population characterized by salt-sensitive hypertension. Low salt diets and diuretics constitute the centrepiece for blood pressure control in CKD. In patients with CKD stage 4, loop diuretics are generally preferred to thiazides. Furthermore, thiazide diuretics have long been held as being of limited efficacy in this population. In this review, by systematically appraising published randomized trials of thiazides in CKD, we show that this class of drugs may be useful even among people with advanced CKD. Thiazides cause a negative sodium balance and reduce body fluids by 1-2 l within the first 2-4 weeks and these effects go along with improvement in hypertension control. The recent CLICK trial has documented the antihypertensive efficacy of chlorthalidone, a long-acting thiazide-like diuretic, in stage 4 CKD patients with poorly controlled hypertension. Overall, chlorthalidone use could be considered in patients with treatment-resistant hypertension when spironolactone cannot be administered or must be withdrawn due to side effects. Hyponatremia, hypokalaemia, volume depletion and acute kidney injury are side effects that demand a vigilant attitude by physicians prescribing these drugs. Well-powered randomized trials assessing hard outcomes are still necessary to more confidently recommend the use of these drugs in advanced CKD.

Revisiting diuretic choice in chronic kidney disease

PURPOSE OF REVIEW

Existing guidelines offer little direction about the use of thiazide and loop diuretics in patients with chronic kidney disease (CKD). This review summarizes recent studies impacting indications and safety considerations for these agents in patients with CKD.

RECENT FINDINGS

Chlorthalidone reduces blood pressure compared to placebo in patients with advanced CKD, challenging the belief that thiazide diuretics lose efficacy at lower glomerular filtration rates (GFR). Existing studies show no clear impact of thiazide or loop diuretic use on kidney or cardiovascular outcomes in patients with CKD. Sodium-glucose co-transporter type 2 (SGLT2) inhibitors have diuretic effects, but concomitant use of a diuretic does not diminish the preventive benefits of these agents against acute kidney injury (AKI). Despite theoretical concerns, thiazide diuretics likely do not worsen circulating vasopressin levels or cyst progression in polycystic kidney disease and may be useful for alleviating polyuria from tolvaptan. Diuretics cause multiple adverse effects, including electrolyte abnormalities, hemodynamic-mediated decrease in estimated GFR, and AKI.

SUMMARY

Recent evidence supports expanded indications for diuretics in patients with kidney disease, including chlorthalidone for hypertension in advanced CKD. Monitoring electrolytes and estimated GFR is critical to ensure patient safety when prescribing these agents for patients with CKD.

Effect of Tolvaptan in Patients with Chronic Kidney Disease Stage G5, and Impact of Concomitant Use of Thiazide Diuretics: A Retrospective Cohort Study

BACKGROUND

The diuretic effect of tolvaptan, a vasopressin V2 receptor antagonist, in patients with severe renal dysfunction remains poorly characterized. Thiazide diuretics reduce urinary volume (UV) in patients with nephrogenic diabetes insipidus, which lacks V2 receptor function.

OBJECTIVE

This retrospective study investigated the acute urinary effects of tolvaptan in patients with stage G5 chronic kidney disease and congestive heart failure (CHF), and the impact of thiazide diuretics on the urinary effects of tolvaptan.

METHODS

UVs 24 h before and after tolvaptan administration and 30-day dialysis initiation rate were compared between patients with and without thiazide diuretic administration.

RESULTS

Thiazide diuretics were used in 26 of the 106 recruited patients (age 73.4 ± 13.0 years; estimated glomerular filtration rate 8.07 ± 3.13 mL/min/1.73 m²). The pre- and post-tolvaptan 24-h UVs were significantly higher in patients not administered thiazide diuretics (1043.4 ± 645.6 vs. 1422.2 ± 774.0 mL/day; p < 0.001) than in those administered thiazide diuretics (1177.3 ± 686.5 vs. 1173.1 ± 629.1 mL/day; p = 0.93). In a multivariate regression model, thiazide diuretic use was significantly associated with decreased 24-h UV (β coefficient - 486.7, 95% confidence interval [CI] - 674.5 to - 298.8); increased urine osmolality (β coefficient 37.7, 95% CI 17.1-58.4); increased body weight (β coefficient 0.62, 95% CI 0.31-0.92); and increased 30-day dialysis initiation rate (odds ratio 3.40, 95% CI 1.18-9.82) after tolvaptan administration.

CONCLUSIONS

Tolvaptan exhibited significant diuretic effects in patients with CHF, including those with severe renal dysfunction, which were diminished with concomitant thiazide diuretic use.

Benefit of natriuresis and cardiac resynchronisation therapy in acute decompensated heart failure with cardiorenal syndrome and hypernatraemia

A man in his eighties with acute heart failure and cardiorenal syndrome developed severe hypernatraemia with diuresis. In this situation, palliation is often considered when renal replacement therapy is inappropriate. The literature to guide treatment of dysnatraemia in this setting is limited. Diuretics often worsen hypernatraemia and fluid replacement exacerbates heart failure. We describe a successful approach to this clinical Catch-22: sequential nephron blockade with intravenous 5% dextrose. Seemingly counterintuitive, the natriuretic effect of this combination had not previously been compared with diuretic monotherapy for heart failure. Yet this immediately effective strategy generated a high natriuresis-to-diuresis ratio and functioned as a bridge to cardiac resynchronisation therapy (CRT). In conjunction with a low salt diet, CRT facilitated the maintenance of sodium homeostasis and fluid balance. Thus, by improving the underlying pathophysiology (ie, inadequate cardiac output), CRT may enhance the outcomes of patients with cardiorenal syndrome and hypernatraemia.

Pharmacotherapeutic principles of fluid management in heart failure

Introduction: Heart failure is a major public health concern that is expected to increase over the decades to come. Despite significant advances, fluid overload and congestion remain a major therapeutic challenge. Vascular congestion and neurohormonal activation are intricately linked and the goal of therapy fundamentally aims to reduce both.Areas covered: The authors briefly review a number of core concepts that elucidate the link between fluid overload and neuro-hormonal activation. This is followed by a review of heart-kidney interactions and the impact of diuresis in this setting. Following an in-depth review of currently available pharmacological agents, the rationale and evidence behind their use, the authors end with a brief note on novel agents/approaches to aid volume management in HF.Expert opinion: A number of non-pharmacological advances in the management of volume overload in heart failure, though promising - are associated with a number of shortcomings. Pharmacological therapy remains the cornerstone of volume management. A number of novel approaches, utilizing existing therapies as well as the emergence of new agents over the past decade bode well for the vulnerable HF population.

Management of Common Cardiovascular Emergencies in Critically Ill Patients

This article reviews treatment and management of common cardiovascular emergencies in critically ill patients, focusing on acute decompensated heart failure, cardiogenic shock, pulmonary embolism, and hypertensive crisis management with inotropes, vasopressors, diuretics, and antiarrhythmic drugs. Clinicians frequently come across challenging clinical scenarios, and there is a gap between evidence-based medicine and clinical practice. Inotropic and vasopressor agents are useful in the acute setting but must be weaned off or used as a bridge for mechanical circulation support devices. Clinicians should aim to lower complications by choosing medications with respect to comorbidities and close the gap between evidence-based medicine and clinical practice.

A Randomized Trial of Distal Diuretics versus Dietary Sodium Restriction for Hypertension in Chronic Kidney Disease

BACKGROUND

Distal diuretics are considered less effective than loop diuretics in CKD. However, data to support this perception are limited.

METHODS

To investigate whether distal diuretics are noninferior to dietary sodium restriction in reducing BP in patients with CKD stage G3 or G4 and hypertension, we conducted a 6-week, randomized, open-label crossover trial comparing amiloride/hydrochlorothiazide (5 mg/50 mg daily) with dietary sodium restriction (60 mmol per day). Antihypertension medication was discontinued for a 2-week period before randomization. We analyzed effects on BP, kidney function, and fluid balance and related this to renal clearance of diuretics.

RESULTS

A total of 26 patients (with a mean eGFR of 39 ml/min per 1.73 m²) completed both treatments. Dietary sodium restriction reduced sodium excretion from 160 to 64 mmol per day. Diuretics produced a greater reduction in 24-hour systolic BP (SBP; from 138 to 124 mm Hg) compared with sodium restriction (from 134 to 129 mm Hg), as well as a significantly greater effect on extracellular water, eGFR, plasma renin, and aldosterone. Both interventions resulted in a similar decrease in body weight and NT-proBNP. Neither approaches decreased albuminuria significantly, whereas diuretics did significantly reduce urinary angiotensinogen and β2-microglobulin excretion. Although lower eGFR and higher plasma indoxyl sulfate correlated with lower diuretic clearance, the diuretic effects on body weight and BP at lower eGFR were maintained. During diuretic treatment, higher PGE2 excretion correlated with lower free water clearance, and four patients developed mild hyponatremia.

CONCLUSIONS

Distal diuretics are noninferior to dietary sodium restriction in reducing BP and extracellular volume in CKD. Diuretic sensitivity in CKD is maintained despite lower diuretic clearance.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

DD-study: Diet or Diuretics for Salt-sensitivity in Chronic Kidney Disease (DD), NCT02875886.

KDOQI US Commentary on the 2017 ACC/AHA Hypertension Guideline

Hypertension is a modifiable risk factor for cardiovascular morbidity and mortality and reduction of elevated blood pressure (BP) remains an important intervention for slowing kidney disease progression. Over the past decade, the most appropriate BP target for initiation and titration of BP-lowering medications has been an area of intense research and debate within the clinical community. In 2017, the American College of Cardiology and the American Heart Association (ACC/AHA) in conjunction with several other professional societies released new hypertension guidelines based on data from a systematic review of clinical trials and observational data. While many of the recommendations in the ACC/AHA hypertension guideline are relevant to nephrology practice, BP targets and management strategies for patients receiving dialysis are not discussed. This Kidney Disease Outcomes Quality Initiative (KDOQI) commentary focuses largely on recommendations from the ACC/AHA hypertension guidelines that are pertinent to individuals at risk of chronic kidney disease or with non-dialysis-dependent chronic kidney disease. This KDOQI commentary also includes a brief discussion of the consensus statement regarding hypertension diagnosis and management for adults receiving maintenance dialysis published by the European Renal and Cardiovascular Medicine Working Group of the European Renal Association-European Dialysis and Transplant Association (ERA-EDTA) and the Hypertension and the Kidney working group of the European Society of Hypertension. Overall, we support the vast majority of the ACC/AHA recommendations and highlight select areas in which best diagnosis and treatment options remain controversial.

Efficacy of triple diuretic treatment in continuous ambulatory peritoneal dialysis patients: A randomized controlled trial

Background

The efficacy of combined diuretic treatment in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) is not known.

Methods

In a single-center, double-blinded, randomized controlled trial, we randomly assigned 51 adult CAPD patients to receive furosemide 1,000 mg/day, hydrochlorothiazide 100 mg/day, and spironolactone 50 mg/day (triple diuretics [TD] group) or furosemide 1,000 mg/day plus placebo (single diuretic [SD] group) for 6 months. The primary outcome was the difference in daily urine output at the 3rd and 6th month of the study compared to baseline (ΔUO) between the SD and TD group. Secondary outcomes were urinary sodium (UNa) and potassium (UK) excretion and overhydration (OH) measured by bioimpedance at 3 and 6 months compared to baseline (ΔUNa, ΔUK, and ΔOH, respectively) and daily glucose exposure (g/day).

Results

Forty-three of 51 patients completed the 6-month trial. The ΔUO at 3 and 6 months was significantly higher in the TD group compared to the SD group (386.32 ± 733.92 mL/day vs. −136.25 ± 629.08 mL/day, P < 0.001, at 3 months; 311.58 ± 640.31 mL/day vs. 120.00 ± 624.07 mL/day, P < 0.001, at 6 months) but there was no significant difference in ΔUNa and ΔUK excretion. Hydration status was significantly better in the TD group (ΔOH 1.84 ± 2.27 L vs. 0.44 ± 1.62 L, P = 0.03, at 3 months; 1.49 ± 2.82 L vs. −0.48 ± 2.61 L, P = 0.02, at 6 months). There was no serious adverse event in this study.

Conclusion

For end-stage renal disease patients on CAPD, the combination of furosemide, hydrochlorothiazide, and spironolactone results in higher urine output and better volume control compared to furosemide alone.

Pathophysiology of antenatal Bartter's syndrome

PURPOSE OF REVIEW

Antenatal Bartter syndrome (aBS) is a heterogenous disease resulting from defective ion transport in the thick ascending limb of the loop of Henle. Novel insights into the pathophysiology, as well as the recent identification of a novel genetic cause of aBS, merit an update on this topic.

RECENT FINDINGS

In aBS, severe salt losing is further aggravated by defective salt sensing in the macula densa, where a reduced tubular salt concentration is perceived and glomerular filtration is increased instead of decreased. As patients with aBS come of age, there is an increased incidence of proteinuria and impaired renal function.Moreover, we recently reported a new form of aBS. Indeed, we described a series of nine families in whom pregnancies with male fetuses where complicated by acute polyhydramnios, preterm delivery and with severe but transient polyuria. We identified mutations in melanoma-associated antigen D2 in all study participants and showed, in vivo and in vitro, reduced expression of the furosemide and thiazide sensitive transporters sodium-potassium-2-chloride cotransporter and sodium chloride cotransporter, respectively.

SUMMARY

Genetic studies revealed the complexity of ion transport in the thick ascending limb of the loop of Henle and will help to clarify the pathophysiology, which is essential to design new therapies.

Treatment of Disorders of Sodium Balance in Chronic Kidney Disease

Extracellular fluid volume expansion is nearly universal in patients with CKD. Such volume expansion has features similar to the syndrome of heart failure with preserved ejection fraction, which not only leads to symptoms but can also lead to further organ damage. Unique treatment challenges are present in this patient population, including low glomerular filtration, which limits sodium chloride filtration, intrinsic tubule predisposition to sodium chloride retention, and proteinuria. In addition, pharmacokinetic considerations alter the disposition of diuretics in patients with CKD and nephrotic syndrome. Maintaining extracellular fluid volume near to normal is often necessary for hypertension treatment in this population, but it may also help prevent progressive cardiovascular and kidney damage. Although powerful diuretics can often accomplish this goal, this often comes at a cost of competing adverse effects. An approach to reduce extracellular fluid volume while avoiding adverse effects, therefore, requires a nuanced yet aggressive therapeutic approach.

A perspective on diuretic resistance in chronic congestive heart failure

Chronic congestive heart failure (CHF) is a complex disorder characterized by inability of the heart to keep up the demands on it, followed by the progressive pump failure and fluid accumulation. Although the loop diuretics are widely used in heart failure (HF) patients, both pharmacodynamic and pharmacokinetic alterations are thought to be responsible for diuretic resistance in these patients. Strategies to overcome diuretic resistance include sodium intake restriction, changes in diuretic dose and route of administration and sequential nephron diuretic therapy. In this review, we discuss the definition, prevalence, mechanism of development and management strategies of diuretic resistance in HF patients.

Hydrochlorothiazide does not increase furosemide's effects in end-stage renal disease

Diuretic therapy for the treatment of edema in patients with end-stage renal disease (ESRD) is unsatisfactory, and a combination of thiazide and loop diuretics may produce better clinical effects. To evaluate the influence of thiazide on loop diuretic therapy for ESRD, we performed a crossover study of furosemide versus hydrochlorothiazide plus furosemide treatment. The diuretic effects of furosemide (160 mg i.v.) alone versus a combination of hydrochlorothiazide (100 mg p.o.) and furosemide were studied in ten ESRD patients with proteinuria greater than 1 g/day. The diuretic effects were compared for 24 h urine volume and electrolyte excretion. To detect the influence of thiazide that may have been obscured in the widely dispersed data, pharmacodynamic analysis of urine furosemide excretion rate versus fractional excretion of sodium (FeNa) was also performed using mixed-effect modeling. Combination therapy was not significantly different from furosemide monotherapy in terms of 24 h urine volume, chloride, or sodium excretion. Hydrochlorothiazide was not a significant covariate in the furosemide effect for the pharmacodynamic model. In patients with ESRD and severe proteinuria (>1,000 mg/day), the combination of hydrochlorothiazide with furosemide therapy did not increase the diuretic effect of furosemide.

Treating Diuretic Resistance: An Overview

Loop diuretics are central to the management of fluid overload in acute decompensated heart failure. However, a variance in the response to loop diuretics can alter a patient's clinical course and has an adverse effect on clinical outcomes. Thus, a diminished response to loop diuretics is an important clinical issue. Factors thought to contribute to diuretic resistance include erratic oral absorption in congested states and postdiuretic sodium retention. Further contributing to diuretic resistance in patients with advanced heart failure are decreases in renal perfusion and alterations in sodium handling that occur in an attempt to maintain circulatory homeostasis. Several pharmacologic interventions have been used to improve diuretic response. Intravenous diuretic administration, increasing diuretic doses, or changing diuretic agents can potentially overcome pharmacokinetic obstacles which contribute to drug resistance. Combination diuretic therapy may be useful to overcome increased sodium retention, dopamine may improve renal perfusion, and hypertonic saline may transiently increase intravascular volume and improve sodium delivery to the tubules of the nephron. Despite the prevalence of diuretic resistance, there remains a paucity of clinical trial evidence to help guide therapy in these patients.

Managing hypertension in patients with chronic kidney disease

Hypertension is a common clinical problem in patients with chronic kidney disease. This article should equip the non-specialty doctor with the general principles pertaining to the investigation and treatment of hypertension in these patients. It also offers a guide to situations that warrant specialty referral.

Hypertension Management in Transition: From CKD to ESRD

Hypertension is present in ∼90% of patients in late-stage CKD. There are scarce data focusing on the transition period between CKD Stages 4 and 5 (end-stage kidney disease) as it relates to hypertension evaluation and management. Here, we propose that a combination of the principles used in the management of patients with CKD Stages 4 and 5 be applied to patients in this transition. These include the use of out-of-office blood pressure (BP) monitoring (eg, home BP), avoidance of excessively tight BP goals, emphasis of sodium restriction, preferential use of blockers of the renin-angiotensin system and diuretics, and consideration of the use of beta blockers.

Sodium and Volume Disorders in Advanced Chronic Kidney Disease

The kidney has a remarkable ability to modulate sodium and water excretion to maintain homeostasis despite a widely varying dietary intake. However, as glomerular filtration rate falls to less than 30 mL/min, this ability can be compromised leading to an increased risk for disorders of serum sodium and extracellular volume. In all cases, these disorders are associated with an increased rate of morbidity and mortality. Management strategies to both prevent and treat these conditions are available but requiring special attention to the unique circumstance of advanced CKD to maximize therapeutic response and prevent complications.

Thiazides in advanced chronic kidney disease: time for a randomized controlled trial

PURPOSE OF REVIEW

Chronic kidney disease is common, associated with increased cardiovascular risk, and frequently complicated by hypertension, requiring multiple agents for control. Thiazides are naturally attractive for use in this population; unfortunately, they are classically thought to be ineffective in advanced chronic kidney disease based on both theoretical considerations and the earliest studies of these agents. This report reviews the studies of thiazide use in chronic kidney disease since the 1970s, including five randomized controlled trials, all of which report at least some degree of efficacy.

RECENT FINDINGS

Two recent studies add further evidence for the utility and efficacy of thiazides in chronic kidney disease. Of these two, one used gold standard ambulatory blood pressure monitoring in patients with poorly controlled hypertension and advanced chronic kidney disease and found chlorthalidone reduces blood pressure. The second is the largest study to date of thiazides in chronic kidney disease; adding a fixed low-dose chlorthalidone as the first diuretic to the antihypertensive regimen improved blood pressure.

SUMMARY

These numerous small but positive studies reinforce the need for a randomized trial to demonstrate safety and efficacy of thiazides in advanced chronic kidney disease.

Thiazide Diuretics in Chronic Kidney Disease

Widely prevalent in the general population, chronic kidney disease (CKD) is frequently complicated with hypertension. Control of hypertension in this high-risk population is a major modifiable cardiovascular and renal risk factor but often requires multiple medications. Although thiazides are an attractive agent, guidelines have previously recommended against thiazide use in stage 4 CKD. We review the updated guidelines on thiazide use in advanced CKD, the antihypertensive mechanism of thiazides, and the clinical studies of thiazides in CKD. Older uncontrolled studies have shown that metolazone reduces blood pressure in CKD, but more recently small randomized controlled trials of hydrochlorothiazide in CKD have shown significant improvement in mean arterial pressure of 15 mmHg. Two recent uncontrolled studies of chlorthalidone including one that used ambulatory blood pressure monitoring found significant improvements in blood pressure. These findings all suggest that thiazides may be efficacious even in advanced CKD; however, electrolyte abnormalities were common in the studies reviewed so close monitoring is necessary during use. Adequately powered randomized trials are now needed before the routine use of thiazide diuretics in advanced CKD can be recommended.

Addition of indapamide to frusemide increases natriuresis and creatinine clearance, but not diuresis, in fluid overloaded ICU patients

BACKGROUND

Fluid and sodium overload are a common problem in critically ill patients. Frusemide may result in diuresis in excess of natriuresis. The addition of indapamide may achieve a greater natriuresis, and also circumvent some of the problems associated with frusemide. The objective of this study was to examine the effect of adding indapamide to frusemide on diuresis, natriuresis, creatinine clearance and serum electrolytes.

METHODS

Fluid overloaded ICU patients were randomised to either intravenous frusemide (Group F) or intravenous frusemide and enteral indapamide (Group F + I). Comprehensive exclusion criteria were applied to address confounders. 24 hour urine was analysed for electrolytes and creatinine. Serum electrolytes were measured before and 24 hours after administration of diuretics.

RESULTS

Forty patients (20 in each group) were included in the study. The groups were similar in their baseline characteristics. Over the 24 h study period, patients in Group F + I, had a larger natriuresis (P = 0.01), chloride loss (P = 0.01) and kaliuresis (P = 0.047). Patients in Group F + I also had a greater 24 hour urinary creatinine clearance (P = 0.01). The 24 hour urine volume and fluid balance was similar between the groups. Patients in Group F had an increase in serum sodium (P = 0.04), while patients in Group F + I had a decrease in both serum chloride (P = 0.01) and peripheral oedema (P < 0.001) during the study duration.

CONCLUSION

In fluid overloaded ICU patients, addition of indapamide to frusemide led to a greater natriuresis and creatinine clearance. Such a strategy might be utilised in optimising sodium balance in ICU patients.

Rationale and Design of the "Safety and Efficacy of the Combination of Loop with Thiazide-type Diuretics in Patients with Decompensated Heart Failure (CLOROTIC) Trial:" A Double-Blind, Randomized, Placebo-Controlled Study to Determine the Effect of Combined Diuretic Therapy (Loop Diuretics With Thiazide-Type Diuretics) Among Patients With Decompensated Heart Failure

BACKGROUND

Fluid overload refractory to loop diuretic therapy can complicate acute or chronic heart failure (HF) management. The Safety and Efficacy of the Combination of Loop with Thiazide-type Diuretics in Patients with Decompensated Heart Failure (CLOROTIC) trial (Clinicaltrials.gov identifier NCT01647932) will test the hypothesis that blocking distal tubule sodium reabsorption with hydrochlorothiazide can antagonize the renal adaptation to chronic loop diuretic therapy and improve diuretic resistance.

METHODS

CLOROTIC is a randomized, placebo-controlled, double-blind, multicenter study. Three hundred and four patients with decompensated HF will be randomly assigned to receive hydrochlorothiazide or placebo in addition to a furosemide regimen. The main inclusion criteria are: age ≥18 years, history of chronic HF (irrespective of etiology and/or ejection fraction), admission for acute decompensation, and previous treatment with an oral loop diuretic for at least 1 month before randomization. The 2 coprimary endpoints are changes in body weight and changes in patient-reported dyspnea during hospital admission. Morbidity, mortality, and safety aspects will also be addressed.

CONCLUSIONS

CLOROTIC is the first large-scale trial to evaluate whether the addition of a thiazide diuretic (hydrochlorothiazide) to a loop diuretic (furosemide) is a safe and effective strategy for improving congestive symptoms resulting from HF. This trial will provide important information and will therefore have a major impact on treatment strategies and future trials in these patients.

Drug management in the elderly adult with chronic kidney disease: a review for the primary care physician

With advancing age, the functional reserve of many organs tends to decrease. In particular, the lean body mass, the levels of serum albumin, the blood flow to the liver, and the glomerular filtration rate are reduced in elderly individuals and can be further impaired by the concomitant presence of acute or chronic kidney disease. Moreover, patients with kidney disease are often affected by comorbid processes and are prescribed multiple medications. The aging process also modifies some drug interactions, including the affinity of some drugs for their receptor, the number of receptors, and the cell responses upon receptor activation. Therefore, older patients with kidney disease are particularly susceptible to the risks of adverse drug reactions. Planning a pharmacological regimen in such patients is confounded by the paucity of information available on the pharmacokinetic and pharmacodynamic profiles of a large number of drugs commonly used in this group of patients. Finally, many aged patients suffer from unintentional poor compliance. In this review, the problems physicians face in designing safe and effective medication management in elderly individuals are discussed, paying attention to those more frequently used, which may be potentially harmful in patients with kidney disease. The risks of overdosing and underdosing are outlined, and some recommendations to reduce the risk of adverse drug reactions are provided. A review of the literature covering the field of drug management in older patients with kidney disease was performed by selecting those articles published between January 1, 1990, and December 1, 2014, using PubMed as a search engine with the keywords elderly, kidney disease, drugs, drug interaction, and renal function.

Renal autoregulation in health and disease

Intrarenal autoregulatory mechanisms maintain renal blood flow (RBF) and glomerular filtration rate (GFR) independent of renal perfusion pressure (RPP) over a defined range (80-180 mmHg). Such autoregulation is mediated largely by the myogenic and the macula densa-tubuloglomerular feedback (MD-TGF) responses that regulate preglomerular vasomotor tone primarily of the afferent arteriole. Differences in response times allow separation of these mechanisms in the time and frequency domains. Mechanotransduction initiating the myogenic response requires a sensing mechanism activated by stretch of vascular smooth muscle cells (VSMCs) and coupled to intracellular signaling pathways eliciting plasma membrane depolarization and a rise in cytosolic free calcium concentration ([Ca(2+)]i). Proposed mechanosensors include epithelial sodium channels (ENaC), integrins, and/or transient receptor potential (TRP) channels. Increased [Ca(2+)]i occurs predominantly by Ca(2+) influx through L-type voltage-operated Ca(2+) channels (VOCC). Increased [Ca(2+)]i activates inositol trisphosphate receptors (IP3R) and ryanodine receptors (RyR) to mobilize Ca(2+) from sarcoplasmic reticular stores. Myogenic vasoconstriction is sustained by increased Ca(2+) sensitivity, mediated by protein kinase C and Rho/Rho-kinase that favors a positive balance between myosin light-chain kinase and phosphatase. Increased RPP activates MD-TGF by transducing a signal of epithelial MD salt reabsorption to adjust afferent arteriolar vasoconstriction. A combination of vascular and tubular mechanisms, novel to the kidney, provides for high autoregulatory efficiency that maintains RBF and GFR, stabilizes sodium excretion, and buffers transmission of RPP to sensitive glomerular capillaries, thereby protecting against hypertensive barotrauma. A unique aspect of the myogenic response in the renal vasculature is modulation of its strength and speed by the MD-TGF and by a connecting tubule glomerular feedback (CT-GF) mechanism. Reactive oxygen species and nitric oxide are modulators of myogenic and MD-TGF mechanisms. Attenuated renal autoregulation contributes to renal damage in many, but not all, models of renal, diabetic, and hypertensive diseases. This review provides a summary of our current knowledge regarding underlying mechanisms enabling renal autoregulation in health and disease and methods used for its study.

Chlorthalidone for poorly controlled hypertension in chronic kidney disease: an interventional pilot study

To test the hypothesis that thiazide-type diuretics effectively lower blood pressure (BP) in moderate to advanced chronic kidney disease (CKD; estimated GFR 20-45 ml/min/ 1.73 m(2)), after confirming poorly controlled hypertension with 24-hour ambulatory BP monitoring, chlorthalidone was added to existing medications in a dose of 25 mg/day, and the dose doubled every 4 weeks if the BP remained elevated. The average age of the 14 subjects was 67.5 years, a median of 4 antihypertensive drugs were used and estimated GFR was 26.8 ± 8.8 ml/min/1.73 m(2). Twelve subjects completed the 12-week treatment phase, and the 24-hour BP, which was 143.1/75.1 mm Hg at baseline, was reduced by 10.5/ 3.1 mm Hg (p = 0.01/p = 0.17). Home BP prior to initiating chlorthalidone was 152.4/82.6 mm Hg and fell at 4, 8, and 12 weeks by 10.2/4.8, 13.4/6.0, and 9.4/3.7 mm Hg (all p < 0.05). Maximal reduction in body weight and total body volume (measured by air displacement plethysmography) was seen at 8 weeks, concurrent with the maximal elevation in serum creatinine concentration and plasma renin activity. Albuminuria was significantly reduced by 40-45%. Adverse events were seen following chlorthalidone therapy in 7 subjects who experienced 18 events as follows: hypokalemia (n = 4), hyperuricemia (4), hyponatremia (3), transient creatinine changes (3), dizziness (2), hyperglycemia (1), and constipation (1). One subject had ischemic stroke during the study. In conclusion, among people with moderate to advanced CKD with poorly controlled hypertension, chlorthalidone may significantly reduce BP via volume contraction; a randomized trial is needed to define the risks and benefits. Adverse effects may occur within a few weeks and should be carefully monitored.

Acute decompensated heart failure: evolving literature and implications for future practice

Acute decompensated heart failure (ADHF) is associated with substantial morbidity and mortality, and represents a considerable financial burden to society. Historically, few prospective, randomized, double-blinded trials have investigated the optimal management of ADHF, and most guideline recommendations are based primarily on expert opinion. However, in the last decade, a considerable amount of research has added to the understanding of the management of ADHF in both patients with fluid overload and low cardiac output. In addition, as mechanical circulatory support devices and heart transplantation continue to evolve, significant advances have also been made with regard to the proper selection of patients for advanced surgical options. Finally, several novel pharmacologic agents have shown promise in early trials and may represent the next steps in ADHF management. Although advances have been made over the past decade, many questions remain.

Resistant hypertension in nondialysis chronic kidney disease

Resistant hypertension (RH) is defined as blood pressure (BP) that remains above the target of less than 140/90 mmHg in the general population and 130/80 mmHg in people with diabetes mellitus or chronic kidney disease (CKD) in spite of the use of at least three full-dose antihypertensive drugs including a diuretic or as BP that reaches the target by means of four or more drugs. In CKD, RH is a common condition due to a combination of factors including sodium retention, increased activity of the renin-angiotensin system, and enhanced activity of the sympathetic nervous system. Before defining the hypertensive patient as resistant it is mandatory to exclude the so-called “pseudoresistance.” This condition, which refers to the apparent failure to reach BP target in spite of an appropriate antihypertensive treatment, is mainly caused by white coat hypertension that is prevalent (30%) in CKD patients. Recently we have demonstrated that “true” RH represents an independent risk factor for renal and cardiovascular outcomes in CKD patients.

Thiazide diuretics in advanced chronic kidney disease

Chronic kidney disease (CKD) is prevalent in 3%-4% of the adult population in the United States, and the vast majority of these people are hypertensive. Compared with those with essential hypertension, hypertension in CKD remains poorly controlled despite the use of multiple antihypertensive drugs. Hypervolemia is thought to be a major cause of hypertension, and diuretics are useful to improve blood pressure control in CKD. Non-osmotic storage of sodium in the skin and muscle may be a novel mechanism by which sodium may modulate hypertension; further work is need to study this novel phenomenon with diuretics. Among people with stage 4 CKD, loop diuretics are recommended over thiazides. Thiazide diuretics are deemed ineffective in people with stage 4 CKD. Review of the literature suggests that thiazides may be useful even among people with advanced CKD. They cause a negative sodium balance, increasing sodium excretion by 10%-15% and weight loss by 1-2 kg in observational studies. Observational data show improvement in seated clinic blood pressure of about 10-15 mm Hg systolic and 5-10 mm Hg diastolic, whereas randomized trials show about 15 mm Hg improvement in mean arterial pressure. Volume depletion, hyponatremia, hypokalemia, hypercalcemia, and acute kidney injury are adverse effects that should be closely monitored. Our review suggests that adequately powered randomized trials are needed before the use of thiazide diuretics can be firmly recommended in those with advanced CKD.

Update in diuretic therapy: clinical pharmacology

All diuretics except spironolactone exert their effects from the lumen of the nephron. Thus, to exert an effect, they must reach the urine. Pharmacokinetics (PK) describes this access. Different edematous disorders can affect access to this site of action and therein affect response to a diuretic. In addition, once a diuretic reaches the site of action, a response ensues. The characteristics of this response that can be affected by a patient's clinical condition are described by the pharmacodynamics (PD) of a diuretic. To understand the mechanisms of abnormal response to a diuretic one must dissect its PK and PD in different edematous disorders. For example, in patients with renal insufficiency, the mechanism of poor diuretic response is PK. In contrast, in patients with cirrhosis or in those with congestive heart failure, it is PD. In patients with nephrotic syndrome, both PK and PD are operative. These different mechanisms mandate differences in therapeutic strategy, as explained in this article.

A pilot study comparing furosemide and hydrochlorothiazide in patients with hypertension and stage 4 or 5 chronic kidney disease

Furosemide is the diuretic of choice for the treatment of hypertension in chronic kidney disease but the adaptative changes in the distal nephron may decrease its efficacy. Hydrochlorothiazide is not believed to be efficient in this setting. In a randomized, double-blind, cross-over trial, 23 patients with hypertension and stage 4 or 5 chronic kidney disease received long-acting furosemide (60 mg) and hydrochlorothiazide (25 mg) for 3 months and then both diuretics for 3 months. Sodium and chloride fractional excretions were measured after 3 months of each diuretic and then after their association. A trend towards an increase in the fractional excretion of sodium and chloride was observed with furosemide and hydrochlorothiazide (P=not significant). The association of the two diuretics increased the fractional excretions of sodium and chloride from 3.4±1.8 to 4.9±2.8 and from 3.8±2.0 to 6.0±3.1, respectively (P<.05). Furosemide and hydrochlorothiazide decreased mean blood pressure by the same extent. The association of the two diuretics was more efficient on blood pressure. There were no differences between furosemide and hydrochlorothiazide with respect to natriuresis and blood pressure control in patients with hypertension and chronic kidney disease.