Diuretics in clinical practice. Part I: mechanisms of action, pharmacological effects and clinical indications of diuretic compounds

A European Renal Association (ERA) synopsis for nephrology practice of the 2023 European Society of Hypertension (ESH) Guidelines for the Management of Arterial Hypertension

In June 2023, the European Society of Hypertension (ESH) presented and published the new 2023 ESH Guidelines for the Management of Arterial Hypertension, a document that was endorsed by the European Renal Association (ERA). Following the evolution of evidence in recent years, several novel recommendations relevant to the management of hypertension in patients with chronic kidney disease (CKD) appeared in these Guidelines. These include recommendations for target office blood pressure (BP) <130/80 mmHg in most and against target office BP <120/70 mmHg in all patients with CKD; recommendations for use of spironolactone or chlorthalidone for patients with resistant hypertension with estimated glomerular filtration rate (eGFR) higher or lower than 30 mL/min/1.73 m2, respectively; use of a sodium-glucose cotransporter 2 inhibitor for patients with CKD and estimated eGFR ≥20 mL/min/1.73 m2; use of finerenone for patients with CKD, type 2 diabetes mellitus, albuminuria, eGFR ≥25 mL/min/1.73 m2 and serum potassium <5.0 mmol/L; and revascularization in patients with atherosclerotic renovascular disease and secondary hypertension or high-risk phenotypes if stenosis ≥70% is present. The present report is a synopsis of sections of the ESH Guidelines that are relevant to the daily clinical practice of nephrologists, prepared by experts from ESH and ERA. The sections summarized are those referring to the role of CKD in hypertension staging and cardiovascular risk stratification, the evaluation of hypertension-mediated kidney damage and the overall management of hypertension in patients with CKD.

Combination Diuretic Therapy to Counter Renal Sodium Avidity in Acute Heart Failure: Trials and Tribulations

In contrast to significant advances in the management of patients with chronic heart failure over the past few years, there has been little change in how patients with acute heart failure are treated. Symptoms and signs of fluid overload are the primary reason for hospitalization of patients who experience acute decompensation of heart failure. Intravenous loop diuretics remain the mainstay of therapy in this patient population, with a significant subset of them showing suboptimal response to these agents leading to incomplete decongestion at the time of discharge. Combination diuretic therapy, that is, using loop diuretics along with an add-on agent, is a widely applied strategy to counter renal sodium avidity through sequential blockade of sodium absorption within renal tubules. The choice of the second diuretic is affected by several factors, including the site of action, the anticipated secondary effects, and the available evidence on their efficacy and safety. While the current guidelines recommend combination diuretic therapy as a viable option to overcome suboptimal response to loop diuretics, it is also acknowledged that this strategy is not supported by strong evidence and remains an area of uncertainty. The recent publication of landmark studies has regenerated the interest in sequential nephron blockade. In this article, we provide an overview of the results of the key studies on combination diuretic therapy in the setting of acute heart failure and discuss their findings primarily with regard to the effect on renal sodium avidity and cardiorenal outcomes.

Diuretics in Different Samples: Update on the Pretreatment and Analysis Techniques

Diuretics are drugs that promote the excretion of water and electrolytes in the body and produce diuretic effects. Clinically, they are often used in the treatment of edema caused by various reasons and hypertension. In sports, diuretics are banned by the World Anti-Doping Agency (WADA). Therefore, in order to monitor blood drug concentration, identify drug quality and maintain the fairness of sports competition, accurate, rapid, highly selective and sensitive detection methods are essential. This review provides a comprehensive summary of the pretreatment and detection of diuretics in various samples since 2015. Commonly used techniques to extract diuretics include liquid-liquid extraction, liquid-phase microextraction, solid-phase extraction, solid-phase microextraction, among others. Determination methods include methods based on liquid chromatography, fluorescent spectroscopy, electrochemical sensor method, capillary electrophoresis and so on. The advantages and disadvantages of various pretreatment and analytical techniques are elaborated. In addition, future development prospects of these techniques are discussed.

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.

Point-of-Care Saliva Osmolarity Testing for the Screening of Hydration in Older Adults With Hypertension

OBJECTIVES

Older adults have an elevated risk of dehydration, a state with proven detrimental cognitive and physical effects. Furthermore, the use of diuretics by hypertensive patients further compounds this risk. This prospective study investigated the diagnostic accuracy of point-of-care (POC) salivary osmolarity (SOSM) measurement for the detection of dehydration in hypertensive adults with and without diuretic pharmacotherapy.

DESIGN

Prospective diagnostic accuracy study.

SETTING

Home visits to patients recruited from 4 community health centers in West Sulawesi, Indonesia.

PARTICIPANTS

A total of 148 hypertensive older adults (57 men, 91 women). The mean ages of male and female patients were 69.4 ± 11.4 and 68.1 ± 7.8 years, respectively.

METHODS

Hypertensive adults were divided into 2 groups based on the presence of diuretics in their pharmacotherapeutic regimen. First-morning mid-stream urine samples were used to perform urine specific gravity (USG) testing. Same-day SOSM measurements were obtained using a POC saliva testing system.

RESULTS

Both USG (P = .0002) and SOSM (P < .0001) were significantly elevated in hypertensive patients with diuretic pharmacotherapy. At a USG threshold of ≥1.030, 86% of diuretic users were classified as dehydrated compared with 55% of non-using participants. A strong correlation was observed between USG and SOSM measurements (r = 0.78, P < .0001). Using a USG threshold of ≥1.030 as a hydration classifier, an SOSM threshold of ≥93 mOsm had a sensitivity of 78.6% and a specificity of 91.1% for detecting dehydration.

CONCLUSIONS AND IMPLICATIONS

Hypertensive patients on diuretics have significantly higher first-morning USG and SOSM values, indicating a higher likelihood of dehydration relative to those on other classes of antihypertensive medication. POC SOSM assessment correlates strongly with first-morning USG assessment, and represents a rapid and noninvasive alternative to urinary hydration assessment that may be applicable for routine use in populations with elevated risk of dehydration.

Preoperative Management of Cardiovascular Medications: A Society for Perioperative Assessment and Quality Improvement (SPAQI) Consensus Statement

Cardiovascular conditions such as hypertension, arrhythmias, and heart failure are common in patients undergoing anesthesia for surgical or other procedures. Numerous guidelines from various specialty societies offer variable recommendations for the perioperative management of these medications. The Society for Perioperative Assessment and Quality Improvement identified a need to provide multidisciplinary evidence-based recommendations for preoperative medication management. The society convened a group of 13 members with expertise in perioperative medicine and training in anesthesiology or internal medicine. The aim of this consensus effort is to provide perioperative clinicians with guidance on the management of cardiovascular medications commonly encountered during the preoperative evaluation. We used a modified Delphi process to establish consensus. Twenty-one classes of medications were identified: α-adrenergic receptor antagonists, angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, angiotensin receptor-neprilysin inhibitors, β-adrenoceptor blockers, calcium-channel blockers, centrally acting sympatholytic medications, direct-acting vasodilators, loop diuretics, thiazide diuretics, potassium-sparing diuretics, endothelin receptor antagonists, cardiac glycosides, nitrodilators, phosphodiesterase-5 inhibitors, class III antiarrhythmic agents, potassium-channel openers, renin inhibitors, class I antiarrhythmic agents, sodium-channel blockers, and sodium glucose cotransportor-2 inhibitors. We provide recommendations for the management of these medications preoperatively.

Diuretic and antiurolithic effect of Garcinia humilis (Vahl) C.D.Adams leaves, a medicinal plant native to South American countries

This study evaluated the diuretic and antiurolithic effect of methanolic extract (MEGHL), dichloromethane (DCM), and ethyl acetate (EtA) fractions obtained from the leaves of Garcinia humilis , a medicinal plant known as achachairu and native to South American countries such as Bolivia, Peru, and Brazil. For the analysis of diuretic effect, the female rats received the treatment with MEGHL (3, 10, and 30 mg/kg), DCM (1, 3 and 10 mg/kg), EtA (1, 3, and 10 mg/kg), hydrochlorothiazide (HCTZ; 10 mg/kg), or vehicle (VEH) after an overload of saline solution. At the end 8-h of the experiment, the urinary parameters were measured . Additionally, the antiurolithic effect was analyzed, in which sodium oxalate was added in synthetic urine in the presence or absence of MEGHL, DCM, and EtA in different concentrations (0.1, 0.3, and 1 mg/mL). MEGHL, DCM, and EtA were able to promote 8-h diuresis in rats. MEGHL treatment at dose 30 mg/kg was accompanied by increased urinary Na + , K + and Cl - excretion. Moreover, the DCM and EtA fractions treatment increased K + and Cl - excretion in the urine, although it does not cause any change in Na + elimination. All the preparations were able to exert an antiurolithic effect in vitro , decreasing the number of calcium oxalate crystals of the monohydrate and dihydrate types. Taking together, the results presented herein showed that the preparations of G. humilis leaves are promising strategies to induce diuresis and antiurolithic effects.

High Prevalence of Multimorbidity and Polypharmacy in Elderly Patients With Chronic Pain Receiving Home Care are Associated With Multiple Medication-Related Problems

Aim: To measure the extent of polypharmacy, multimorbidity and potential medication-related problems in elderly patients with chronic pain receiving home care. Methods: Data of 355 patients aged ≥65 years affected by chronic pain in home care who were enrolled in the ACHE study in Berlin, Germany, were analyzed. History of chronic diseases, diagnoses, medications including self-medication were collected for all patients. Multimorbidity was defined as the presence of ≥2 chronic conditions and levels were classified by the Charlson-Comorbidity-Index. Polypharmacy was defined as the concomitant intake of ≥5 medications. Potentially clinically relevant drug interactions were identified and evaluated; underuse of potentially useful medications as well as overprescription were also assessed. Results: More than half of the patients (55.4%) had moderate to severe comorbidity levels. The median number of prescribed drugs was 9 (range 0-25) and polypharmacy was detected in 89.5% of the patients. Almost half of them (49.3%) were affected by excessive polypharmacy (≥10 prescribed drugs). Polypharmacy and excessive polypharmacy occurred at all levels of comorbidity. We detected 184 potentially relevant drug interactions in 120/353 (34.0%) patients and rated 57 (31.0%) of them as severe. Underprescription of oral anticoagulants was detected in 32.3% of patients with atrial fibrillation whereas potential overprescription of loop diuretics was observed in 15.5% of patients. Conclusion: Multimorbidity and polypharmacy are highly prevalent in elderly outpatients with chronic pain receiving home care. Medication-related problems that could impair safety of drug treatment in this population are resulting from potentially relevant drug interactions, overprescribing as well as underuse.

Prolonged Diuretic and Renoprotective Effects of a Xanthone Obtained from Garcinia achachairu Rusby in Normotensive and Hypertensive Rats

The previous study showed that 1,5,8-trihydroxy-4',5'-dimethyl-2H-pyrano(2,3 : 3,2)-4-(3-methylbut-2-enyl) xanthone (TDP) obtained from Garcinia achachairu Rusby (Clusiaceae) branches induces acute diuresis in normotensive (NTR) and spontaneously hypertensive rats (SHR) after 8 h of the experiment. In complementarity, the present study evaluated the prolonged diuretic and renoprotective effects of TDP in both NTR and SHR. The animals received, once a day, oral treatment with TDP (0.1 mg/kg), hydrochlorothiazide (10 mg/kg), or vehicle (VEH; 10 mL/kg). At the end of 7 days, the urine, blood, and kidney samples were collected for biochemical and histological analyzes. The urinary volume of both NTR and SHR after 7 days of treatment with the TDP was significantly increased, associated with augmented urinary electrolyte excretion levels. The treatments did not modify the urinary pH values nor the parameters analyzed in plasma (Na⁺, K⁺, Cl^-, and Ca²⁺). Concerning the renal analyzes, when compared with the VEH-treated NTR group, while the activity of the enzymes catalase (CAT) and N-acetyl-β-D-glucosaminidase (NAG), as well as nitrite levels, were increased, the generation of lipid hydroperoxides and the activity of the enzyme myeloperoxidase (MPO) were unaltered. On the other hand, the activities of superoxide dismutase (SOD) and glutathione S-transferase (GST) and the levels of reduced glutathione (GSH) in kidney homogenates of the SHR group were decreased. However, TDP augmented the levels of GSH and GST activities and reduced the levels of nitrite and the activities of CAT and MPO, when compared with VEH-treated only SHR. Besides, the treatment with TDP alleviated the morphological changes of the renal corpuscle region of SHR. Together, these results revealed the prolonged diuretic effect of TDP and their renal protective effect by improving the antioxidative capacity.

Diuretic Effect and Metabolomics Analysis of Crude and Salt-Processed Plantaginis Semen

Plantaginis Semen (PS) is well recognized in traditional Chinese medicine (TCM) and health products. Crude PS (CPS) and salt-processed CPS (SPS) are the two most commonly used decoction pieces of PS, and are included in the 2020 edition of Chinese Pharmacopoeia. Although they all have multiple effects, the mechanisms for treating diseases are different and remain unclear, the processing mechanism of SPS is also indeterminate, which hinders their clinical application to a certain extent. In order to solve these problems and further develop PS in the clinical application. Here, we used saline-loaded model rats for experiments, and utilized an integrated approach consisting of pharmacological methods and metabolomics, which could assess the diuretic impact of CPS and SPS ethanol extracts on saline-loaded rats and elucidate the underlying mechanism. The results showed that CPS and SPS both produced increased urine volume excretion and urine electrolyte excretion, but the levels of aldosterone (ALD) and aquaporin 2 (AQP2) were decreased. And 30 differential metabolites such as linoleic acid, lysoPC(O-18:0), sphingosine-1-phosphate, lysoPC(18:0) were found, mainly involving three metabolic pathways. In conclusion, CPS and SPS both have a diuretic effect, and that of SPS is better. This work investigated the possible diuretic mechanisms of CPS and SPS which may also be the mechanism of PS for anti-hypertension. In addition, a holistic approach provided novel and helpful insights into the underlying processing mechanisms of TCM.

Evaluation of the Diuretic Activity of the Aqueous and 80% Methanol Extracts of Ficus sur Forssk (Moraceae) Leaves in Saline-loaded Rats

Background

Although investigations on different pharmacological activities of the experimental plant, Ficus sur have been conducted, its folklore use for diuresis has not yet been validated. The current study, therefore, focused on the diuretic activity of aqueous and 80% methanol extracts of F. sur Forssk. leaves in rats.

Methods

Rats were randomly assigned into eight groups each consisting of six rats. Test groups received either 100 mg/kg, 200 mg/kg, or 400 mg/kg of aqueous or 80% methanol leaves extract. The negative control group and positive control were treated with 2 mL/100 g of distilled water and furosemide (10 mg/kg), respectively. Thereafter urine volume was recorded every hour until the end of the fifth hour, and cumulative urine volume of each rat was measured. Then, diuretic activity, diuretic index, saliuretic index, natriuretic index and carbonic anhydrase inhibition index in each group were calculated, and results were compared among the groups.

Results

The middle (200 mg/kg) and the highest (400 mg/kg) doses of both extracts significantly increased diuresis at the fifth hour (p<0.001) compared to the negative control, although the diuretic activity was less than that of the positive control. Regarding electrolyte excretion, all dose levels of both extracts showed significant natriuresis (p<0.001) and chloriuresis (p<0.01) compared to the negative control. Aqueous extract displayed more significant diuretic effect than 80% methanol extract. The aqueous and 80% methanol extracts produced alkaline urine.

Conclusion

The crude leaves extracts of F. sur increased urinary excretion and concentration of urinary electrolytes in a dose-dependent manner. These findings are in agreement with the traditional claim for use of F. sur as diuretic agent.

The acute diuretic effects with low-doses of natural prenylated xanthones in rats

The diuretic effect of 3-demethyl-2-geranyl-4-prenylbellidypholine xanthone (DGP) and 1,5,8-trihydroxy-4',5'-dimethyl-2H-pyrano(2,3:3,2)-4-(3-methylbut-2-enyl) xanthone (TDP), two natural prenylated xanthones, was investigated in female normotensive (NTR) and spontaneously hypertensive rats (SHR). The rats received a single treatment with DGP, TDP, hydrochlorothiazide (HCTZ), or vehicle (VEH) after an oral load of physiological saline. The effects of DGP and TDP in combination with diuretics of clinical use, as well as with L-NAME, atropine and indomethacin were also explored. The urinary parameters were measured at the end of the 8-h experiment. When orally given to rats, DGP was able to increase the urine volume, at doses of 0.03-0.3 mg/kg, associated with a K⁺-sparing effect. TDP, in turn, at doses of 0.03-0.3 mg/kg, induced diuresis and saluresis (i.e. augmented urinary levels of Na⁺ and Cl^-) in NTR, while decreased the urinary content of Ca²⁺ in both NTR and SHR. The combination with HCTZ, but not with furosemide or amiloride, significantly enhanced DGP and TDP induced diuresis, which was accompanied by an increase of the electrolytes content in the urine. Instead, amiloride in combination with DGP or TDP enhanced urinary Na⁺ and Cl^- and decreased K⁺ elimination. Furthermore, the effect of DGP and TDP were heightened after pretreatment with L-NAME. While atropine was able to prevent DGP-induced diuresis, the pretreatment with indomethacin precluded TDP-induced diuresis. Besides, TDP exerted protective effects against urinary calcium oxalate crystals formation. Taken together, our data revealed the diuretic effect of two xanthones in rats and their possible underlying mode of action.

Hypertension, antihypertensive medications use and risk of age-related macular degeneration in California Teachers Cohort

Sustained and inadequately controlled hypertension can promote the development of age-related macular degeneration (AMD) through multiple biologic pathways. Epidemiologic studies of high blood pressure, antihypertensive therapies, and the risk of AMD thus far have been inconclusive. However, few studies evaluated risks according to the use of different classes of antihypertensive drugs or took combinations of use into account. We performed a prospective cohort study by linking the California Teachers Study (CTS) cohort (N = 88 481) to statewide hospital discharge records up to December 31, 2012. History of high blood pressure, regular use of antihypertensive medications, and comprehensive risk factor information was collected via self-administered questionnaires at baseline in 1995-1996, and information on specific classes of antihypertensive drugs was provided by a subsample of CTS participants who completed a follow-up questionnaire in 2000. We identified 1762 female teachers with AMD during 14.8 years of follow-up on average. Applying Cox proportional hazard regression, we estimated increased risks of AMD among women treated for hypertension at baseline (HR = 1.15, 95% CI: 1.03, 1.30); the magnitude of the association increased with longer duration of antihypertensive treatment. In the subsample with more specific information on type of medication use, we estimated a 45% increased risk of AMD among women receiving diuretics as monotherapy compared to women with medications more potent than diuretics (HR = 1.45, 95% CI 1.10, 1.90). In women treated with a combination of antihypertensive drugs, we observed no increased risk of AMD for any individual class of drugs.

SGLT-2 inhibitors and nephroprotection: current evidence and future perspectives

Chronic kidney disease (CKD) is a major public health issue and an independent risk factor for cardiovascular and all-cause mortality. Diabetic kidney disease develops in 30-50% of diabetic patients and it is the leading cause of end-stage renal disease in the Western world. Strict blood pressure control and renin-angiotensin system (RAS) blocker use are the cornerstones of CKD treatment; however, their application in everyday clinical practice is not always ideal and in many patients CKD progression still occurs. Accumulated evidence in the past few years clearly suggests that sodium-glucose co-transporter-2 (SGLT-2) inhibitors present potent nephroprotective properties. In clinical trials in patients with type 2 diabetes mellitus, these agents were shown to reduce albuminuria and proteinuria by 30-50% and the incidence of composite hard renal outcomes by 40-50%. Furthermore, their mechanism of action appears rather solid, as they interfere with the major mechanism of proteinuric CKD progression, i.e., glomerular hypertension and hyperfiltration. The present review summarizes the current evidence from human trials on the effects of SGLT-2 inhibitors on nephroprotection and discusses their position in everyday clinical practice.

Development and Validation of Two Robust Stability-Indicating Chromatographic Methods for Determination of Metolazone in Drug Substance and Pharmaceutical Dosage Form in the Presence of Its Degradation Products and Characterization of Main Degradation Products Based on LC-MS

Two robust and selective stability-indicating chromatographic methods were developed and validated for the determination of metolazone in drug substance and pharmaceutical dosage form in the presence of its degradation products. The HPLC method employed a Kromasil C18 (250 × 4.6,5 μm) column and a mobile phase of acetonitrile: 0.2% orthophosphoric acid (32:68 v/v) at a flow rate 2 mL/min and detection at 238 nm. The separation was performed in HPLC isocratic mode. The robustness of the suggested method was assessed using the Plackett-Burman design, parameters affecting system suitability were established and non-significant intervals for the significant parameters were considered. The HPTLC method employed Nano-SIL-20 UV254 HPTLC plates as adsorbent, ethyl acetate: toluene: acetic acid solution (4:4:0.5, v/v/v), as a developing solvent system and densitometric detection at 238 nm. Metolazone was exposed to different stress conditions, including acid and alkaline hydrolysis and oxidative and photolytic degradation. The main degradation products obtained have been characterized and interpreted based on LC-MS. The linearity of the suggested methods was proved in the concentration range of 20-75 μg/mL for the HPLC method and 100-900 ng/spot for the HPTLC method. The suggested methods were validated according to international conference on harmonization guidelines. These methods were successfully dedicated for the estimation of metolazone in drug substance and pharmaceutical dosage form in the presence of its degradation products. The results of the suggested methods were evaluated and compared statistically with results obtained by an official method without finding any significant difference.

Pharmacotherapy of hypertension in patients with pre-dialysis chronic kidney disease

INTRODUCTION

Hypertension is the most common co-morbidity in patients with chronic kidney disease (CKD), with prevalence gradually increasing across CKD Stages to the extent that about 90% of end-stage renal disease (ESRD) patients are hypertensives. Several factors contribute to blood pressure (BP) elevation and guide the therapeutic interventions that should be employed in these patients.

AREAS COVERED

This review summarizes the existing data for the management of hypertension, regarding optimal BP targets and the use of major antihypertensive classes in patients with CKD.

EXPERT OPINION

Management of hypertension in CKD requires both lowering BP levels and reducing proteinuria to minimize the risk of both CKD progression and cardiovascular disease. In this respect, aggressive control of office BP to levels <130/80 mmHg has long been proposed for patients with proteinuric nephropathies. Following evidence from recent studies that confirmed significant reductions in renal and cardiovascular outcomes with strict BP control, most, but not all, of international guidelines, suggest such BP goals for all hypertensive patients, including those with CKD. Use of renin-angiotensin system (RAS) blockers is the treatment of choice for patients with proteinuric nephropathies, while, in most patients with CKD, combination treatment with two, three, or more antihypertensive agents is often required to control BP.

The effect of SGLT-2 inhibitors on blood pressure: a pleiotropic action favoring cardio- and nephroprotection

Strict blood pressure (BP) control in patients with diabetes is associated with reductions in cardiovascular and renal risk. SGLT-2 inhibitors act in the proximal tubule to reduce glucose reabsorption. They also have mild natriuretic and diuretic effects, combining properties of proximal tubule diuretics and osmotic diuretics, which are expected to reduce BP. Several lines of evidence suggests that SGLT-2 inhibitors produce mild but meaningful reductions in BP and also decrease the incidence of renal outcomes, cardiovascular events and mortality. Thus, recent guidelines for type 2 diabetes suggest that among oral agents to use together with metformin, SGLT-2 inhibitors should be preferred in patients at increased cardiovascular risk, kidney disease or heart failure. This review summarizes current literature on the effect of SGLT-2 inhibitors on BP, and its potential relationships with cardio- and nephroprotection.

Approach and management of dysnatremias in cirrhosis

Hypervolemic (dilutional) hyponatremia is the most common dysnatremia in cirrhosis, with a prevalence close to 50% in patients with ascites, while hypovolemic hyponatremia occurs in a minority of cases. Hyponatremia carries a poor prognosis, being associated with increased mortality and reduced survival after liver transplantation. Hypernatremia is rarer and is also associated with an adverse prognosis. Increased non-osmotic secretion of arginine vasopressin and altered renal tubular sodium handling due to impaired free water generation are the mechanisms leading to hypervolemic hyponatremia, while diuretic-induced fluid loss is the main cause of hypovolemic hyponatremia. Hypernatremia usually follows hypotonic fluid losses due to osmotic diuresis (glycosuria) or lactulose-induced diarrhea. The main clinical manifestations of dysnatremias are due to their effects on the central nervous system: astroglial cell hyperhydration follows hyponatremia-an abnormality that exacerbates ammonia neurotoxicity-while the opposite abnormality occurs with hypernatremia. Asymptomatic or mildly symptomatic hypervolemic hyponatremia is mainly managed by correcting of precipitating factors and non-osmotic fluid restriction. Severe, life-threatening hyponatremia requires hypertonic saline infusion, avoiding rapid and complete correction of serum sodium concentration to prevent neurological sequelae such as osmotic demyelination. V₂ receptor blockade by vaptans may be considered in patients with sustained hyponatremia waitlisted for liver transplantation. Diuretic withdrawal and plasma volume expansion are required in hypovolemic hypernatremia. Prompt recognition, removal of the precipitating factor(s) and non-osmotic fluid administration represent the mainstays of hypernatremia management. Rapid correction of long-standing hypernatremia can lead to cerebral edema and has to be avoided.

Casein kinase 1α: biological mechanisms and theranostic potential

Casein kinase 1α (CK1α) is a multifunctional protein belonging to the CK1 protein family that is conserved in eukaryotes from yeast to humans. It regulates signaling pathways related to membrane trafficking, cell cycle progression, chromosome segregation, apoptosis, autophagy, cell metabolism, and differentiation in development, circadian rhythm, and the immune response as well as neurodegeneration and cancer. Given its involvement in diverse cellular, physiological, and pathological processes, CK1α is a promising therapeutic target. In this review, we summarize what is known of the biological functions of CK1α, and provide an overview of existing challenges and potential opportunities for advancing theranostics.

Gallic acid, a phenolic compound isolated from Mimosa bimucronata (DC.) Kuntze leaves, induces diuresis and saluresis in rats

Although present in the leaves of Mimosa bimucronata (DC.) and many other medicinal plants commonly used to augment urinary volume excretion, the effects of gallic acid as a diuretic agent remain to be studied. Wistar rats were orally treated with vehicle, hydrochlorothiazide, or gallic acid. The effects of gallic acid in the presence of hydrochlorothiazide, furosemide, amiloride, L-NAME, atropine, and indomethacin were also investigated. Diuretic index, pH, conductivity, and electrolyte excretion were evaluated at the end of the experiment (after 8 or 24 h). Gallic acid induced diuretic and saluretic (Na⁺ and Cl^-) effects, without interfering with K⁺ excretion, when orally given to female and male rats at a dose of 3 mg/kg. These effects were associated with increased creatinine and conductivity values while pH was unaffected by any of the treatments. Plasma Na⁺, K⁺, and Cl^- levels were not affected by any of the acute treatments. The combination with hydrochlorothiazide or furosemide was unable to intensify the effects of gallic acid when compared with the response obtained with each drug alone. On the other hand, the treatment with amiloride plus gallic acid amplified both diuresis and saluresis, besides to a marked potassium-sparing effect. Its diuretic action was significantly prevented in the presence of indomethacin, a cyclooxygenase inhibitor, but not with the pretreatments with L-NAME or atropine. Although several biological activities have already been described for gallic acid, this is the first study demonstrating its potential as a diuretic agent.

Garlic extract increases non-clipped kidney tubular natriuresis and diuresis in the 2-kidney, 1-clip rat model: Significance in hypertension

BACKGROUND

Angiotensin II (AngII) is a potent modulator of vascular tone and renal clearance function. Raw garlic aqueous extract (RGAE) inhibits angiotensin I converting enzyme (ACE) dipeptidase activity and therefore AngII generation in the 2-kidney, 1-clip rat model (2K-1Cr).

OBJECTIVE

This study investigated the effect of RGAE on the non-clipped kidney clearance function and blood pressure (BP) in the 2 K-1Cr.

METHOD

2K-1Cr were anesthetized, cannulated and instrumentalized and the acute effect during the first hour post-administration of a single intravenous dose of RGAE (30mg/100gb.wt/0.3ml) was tested on: 1- The ACE dipeptidase activity estimated from a reduction in the vasopressor action of angiotensin I [(AngI, 200ng/0.2ml): the precursor of AngII] in one group (n=5); 2- The non-clipped (left) kidney (LK) clearance function in a second group (n=6). Similar protocols were carried out on two groups of normal rats (Nr: n=5+n=6).

RESULTS

In the 2K-1Cr, RGAE partially, however significantly, decreased the vasopressor action of AngI. Furthermore, RGAE had no effect on systolic BP, mean BP, plasma osmolarity, LK cortical circulation or glomerular filtration rate. Alternatively, RGAE significantly increased LK urine volume, fractional excretion of water, sodium clearance and fractional excretion of sodium; while significantly decreasing heart rate and LK urine osmolarity.

CONCLUSIONS

Our findings suggest that a single i.v. dose of RGAE causes ACE dipeptidase inhibition, thus reducing AngII generation and bioavailability in the 2K-1Cr. This action of RGAE enhances the non-clipped kidney clearance of sodium and water by modulating the tubular handling mechanisms.

Chemical composition and diuretic, natriuretic and kaliuretic effects of extracts of Mimosa bimucronata (DC.) Kuntze leaves and its majority constituent methyl gallate in rats

Objectives

Some species of the genus Mimosa showed promising results in previous investigations, which include diuretic effect; however, no chemical analyses or animal model has been conducted so far to evaluate the biological properties of M. bimucronata.

Methods

Male Wistar rats received the oral treatment with vehicle; hydrochlorothiazide; methanolic extract from M. bimucronata (MEMB), dichloromethane (DCM) and ethyl acetate (EA) fractions or methyl gallate (MG). The cumulative urine volume, electrolytes excretion, pH and osmolality were determined at the end of the experiment.

Key findings

The chemical studies demonstrated that the phenolic compounds are the majorities in the plant, with the MG being the main substance identified. We showed that MEMB and EA fraction, but not DCM, exhibited diuretic and saluretic effects. Similarly, the MG also revealed diuretic, natriuretic and kaliuretic properties to both normotensive and spontaneously hypertensive rats. Atropine, a muscarinic receptor antagonist, fully prevented MG-induced diuresis and saluresis. In addition, MG did not alter the viability of A7r5 and L929 cell lines and neither stimulated nitric oxide generation.

Conclusions

These findings suggest that M. bimucronata extracts and its majority compound MG present diuretic, natriuretic and kaliuretic properties, which was dependent on the activation of muscarinic acetylcholine receptor.

Diuretic and natriuretic effect of luteolin in normotensive and hypertensive rats: Role of muscarinic acetylcholine receptors

BACKGROUND

Luteolin is a very common phenolic compound found in a wide variety of natural products. Although several biological properties have already been described regarding the beneficial effect of luteolin in the cardiovascular and renal system, no scientific research explored its potential effect as a diuretic agent in experimental trials.

METHODS

Groups of male normotensive (NTR) and spontaneously hypertensive rats (SHR) were orally treated with vehicle, hydrochlorothiazide or luteolin. In another experimental set, in order to verify the possible mechanisms of luteolin-induced diuresis, NTR were treated with vehicle, hydrochlorothiazide, amiloride, L-NAME, indomethacin or atropine, 1h before receiving luteolin. The cumulative urine volume, electrolytes excretion, pH and osmolality were measured at the end of the experiment (after 8h).

RESULTS

Luteolin, at dose of 3mg/kg, was able to induce both diuretic and natriuretic effect in NTR and SHR groups, without interfering with urinary pH, K⁺ or Cl^- levels. While Ca²⁺ content remained unchanged in urine from luteolin-treated group of NTR, luteolin reduced Ca²⁺ excretion in urine from SHR. The treatment with HCTZ and amiloride intensified luteolin-induced diuresis and natriuresis, with an interesting potassium-sparing effect, in addition to an increase in urinary osmolality levels. Moreover, the diuretic and natriuretic action of luteolin was fully avoided in the presence of atropine, a non-selective muscarinic receptor antagonist.

CONCLUSIONS

This study revealed the diuretic and natriuretic effect of luteolin in normotensive and hypertensive rats. Our data also showed the involvement of muscarinic acetylcholine receptors for the renal effects of luteolin.

Sodium-glucose cotransporter-2 inhibitors and blood pressure decrease: a valuable effect of a novel antidiabetic class?

Diabetes mellitus is a major issue of public health, affecting more than 300 million people worldwide. Inhibitors of the sodium-glucose cotransporter-2 (SGLT-2) in the renal proximal tubule are a novel class of agents for the treatment of type 2 diabetes mellitus. Inhibition of the SGLT-2 results in reduced glucose reabsorption and improvement in glycemic control. Alongside glucose excretion, SGLT-2 inhibitors also have mild natriuretic and diuretic effects, combining actions of a proximal tubule diuretic and an osmotic diuretic; these properties are expected to lead to small blood pressure (BP) reductions. Clinical studies with dapagliflozin, canagliflozin, empagliflozin, ipragliflozin, luseogliflozin, and tofogliflozin used either as monotherapy or add-on therapy and compared with placebo or active treatment have also examined the effect of these agents on BP as a secondary endpoint. Although with some differences between individual agents, all of the approved SGLT-2 inhibitors provided a mild but meaningful reduction in office SBP and DBP. Recent studies with the use of ambulatory blood pressure monitoring suggest that the magnitude of this BP reduction can be even greater. The aim of this review is to systematically summarize and present the studies reporting the effect of approved SGLT-2 inhibitors on BP.