Diuretics in the treatment of hypertension. Part 2: loop diuretics and potassium-sparing agents

Canagliflozin regulates metabolic reprogramming in diabetic kidney disease by inducing fasting-like and aestivation-like metabolic patterns

AIMS/HYPOTHESIS

Sodium-glucose co-transporter 2 (SGLT2) inhibitors (SGLT2i) are antihyperglycaemic drugs that protect the kidneys of individuals with type 2 diabetes mellitus. However, the underlying mechanisms mediating the renal benefits of SGLT2i are not fully understood. Considering the fuel switches that occur during therapeutic SGLT2 inhibition, we hypothesised that SGLT2i induce fasting-like and aestivation-like metabolic patterns, both of which contribute to the regulation of metabolic reprogramming in diabetic kidney disease (DKD).

METHODS

Untargeted and targeted metabolomics assays were performed on plasma samples from participants with type 2 diabetes and kidney disease (n=35, 11 women) receiving canagliflozin (CANA) 100 mg/day at baseline and 12 week follow-up. Next, a systematic snapshot of the effect of CANA on key metabolites and pathways in the kidney was obtained using db/db mice. Moreover, the effects of glycine supplementation in db/db mice and human proximal tubular epithelial cells (human kidney-2 [HK-2]) cells were studied.

RESULTS

Treatment of DKD patients with CANA for 12 weeks significantly reduced HbA1c from a median (interquartile range 25-75%) of 49.0 (44.0-57.0) mmol/mol (7.9%, [7.10-9.20%]) to 42.2 (39.7-47.7) mmol/mol (6.8%, [6.40-7.70%]), and reduced urinary albumin/creatinine ratio from 67.8 (45.9-159.0) mg/mmol to 47.0 (26.0-93.6) mg/mmol. The untargeted metabolomics assay showed downregulated glycolysis and upregulated fatty acid oxidation. The targeted metabolomics assay revealed significant upregulation of glycine. The kidneys of db/db mice undergo significant metabolic reprogramming, with changes in sugar, lipid and amino acid metabolism; CANA regulated the metabolic reprogramming in the kidneys of db/db mice. In particular, the pathways for glycine, serine and threonine metabolism, as well as the metabolite of glycine, were significantly upregulated in CANA-treated kidneys. Glycine supplementation ameliorated renal lesions in db/db mice by inhibiting food intake, improving insulin sensitivity and reducing blood glucose levels. Glycine supplementation improved apoptosis of human proximal tubule cells via the AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway.

CONCLUSIONS/INTERPRETATION

In conclusion, our study shows that CANA ameliorates DKD by inducing fasting-like and aestivation-like metabolic patterns. Furthermore, DKD was ameliorated by glycine supplementation, and the beneficial effects of glycine were probably due to the activation of the AMPK/mTOR pathway.

Improving diagnosis and treatment of hypomagnesemia

Magnesium is one of the most abundant cations in the body and acts as a cofactor in more than 600 biochemical reactions. Hypomagnesemia is a highly prevalent condition, especially in subjects with comorbid conditions, but has received less attention than other electrolyte disturbances. This review will discuss magnesium physiology, absorption, storage, distribution across the body, and kidney excretion. After reviewing the regulation of magnesium homeostasis, we will focus on the etiology and clinical presentation of hypomagnesemia. The role of laboratory medicine in hypomagnesemia will be the main purpose of this review, and we will discuss the laboratory tests and different samples and methods for its measurement. Although free magnesium is physiologically active, total serum magnesium is the most commonly used measurement in laboratory medicine and is apt for clinical purposes; however, it is not appropriately used, and many patients with hypomagnesemia remain undiagnosed and not treated. Using information technologies, laboratory medicine can largely improve the diagnosis and treatment of hypomagnesemia through the design and establishment of automatic demand management and result management interventions by acting in the first and last steps of the laboratory cycle, test requests, and actions taken after test results, to unmask patients with hypomagnesemia and improve the number of patients undergoing treatment.

Resistant hypertension: consensus document from the Korean society of hypertension

Although reports vary, the prevalence of true resistant hypertension and apparent treatment-resistant hypertension (aTRH) has been reported to be 10.3% and 14.7%, respectively. As there is a rapid increase in the prevalence of obesity, chronic kidney disease, and diabetes mellitus, factors that are associated with resistant hypertension, the prevalence of resistant hypertension is expected to rise as well. Frequently, patients with aTRH have pseudoresistant hypertension [aTRH due to white-coat uncontrolled hypertension (WUCH), drug underdosing, poor adherence, and inaccurate office blood pressure (BP) measurements]. As the prevalence of WUCH is high among patients with aTRH, the use of out-of-office BP measurements, both ambulatory blood pressure monitoring (ABPM) and home blood pressure monitoring (HBPM), is essential to exclude WUCH. Non-adherence is especially problematic, and methods to assess adherence remain limited and often not clinically feasible. Therefore, the use of HBPM and higher utilization of single-pill fixed-dose combination treatments should be emphasized to improve drug adherence. In addition, primary aldosteronism and symptomatic obstructive sleep apnea are quite common in patients with hypertension and more so in patients with resistant hypertension. Screening for these diseases is essential, as the treatment of these secondary causes may help control BP in patients who are otherwise difficult to treat. Finally, a proper drug regimen combined with lifestyle modifications is essential to control BP in these patients.

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.

Clinical predictors of hyponatremia in patients with heart failure according to severity of chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) has been associated with adverse clinical outcomes. Hyponatremia, a marker of illness severity and poor prognosis, is commonly exhibited in patients with CKD.

METHODS

This cross-sectional study included patients hospitalized due to heart failure (HF). We used stepwise logistic regression to investigate the independent association of cardiovascular drugs, markers of HF severity, and baseline clinical characteristics with hyponatremia in three subgroups; normal renal function, mild-to-moderate CKD, and severe CKD.

RESULTS

Of the 1232 patients, 38.6% were hyponatremic. Patients with severe CKD, compared to those with normal renal function and mild-to-moderate CKD, were more likely to be hyponatremic (47.1%, 34.4% and 36.6%, respectively; p ≤ 0.0001). Alcohol consumption, female sex, n-terminal pro-brain natriuretic peptide (NT-proBNP), hydrochlorothiazide (HCT), and mineralocorticoid receptor antagonist (MRA) use, or angiotensin II receptor I blocker (ARB) non-use were associated with hyponatremia in patients with normal renal function (p ≤ 0.03 in all cases). Current smoking, diabetes mellitus, NT-proBNP, loop diuretic dose, and MRA use were predictors in mild-to-moderate CKD (p ≤ 0.04 in all cases). ARB use, loop diuretic dose, and HCT use were predictors in severe CKD (p ≤ 0.03 in all cases). Non-use of dihydropyridine calcium channel blocker (CCB) was an independent predictor of hyponatremia in all CKD stages (p ≤ 0.04 in all cases).

CONCLUSION

Apart from a firm favorable effect of CCBs, cardiovascular therapy should be carefully tailored to avoid hyponatremia in patients with cardiorenal syndrome.

Drug-drug interactions involving antipsychotics and antihypertensives

INTRODUCTION

Antipsychotics represent the mainstay in the treatment of patients diagnosed with major psychiatric disorders. Hypertension, among other components of metabolic syndrome, is a common finding in these patients. For their psychiatric and physical morbidity, many patients receive polypharmacy, exposing them to the risk of clinically relevant drug-drug interactions.

AREAS COVERED

This review summarizes the knowledge regarding the known or potential drug-drug interactions between antipsychotics and the main drug classes used in the treatment of hypertension. We aimed to provide the clinician an insight into the pharmacokinetic and pharmacodynamic interactions between these drugs for a better choice of combinations of drugs to treat both the mental illness and cardiovascular risk factors. For this, we performed a literature search in PubMed and Scopus databases, up to 31 July 2021.

EXPERT OPINION

The main pharmacokinetic interactions between antipsychotics and antihypertensive drugs involve mainly the cytochrome P450 system. The pharmacodynamic interactions are produced by multiple mechanisms, leading to concurrent binding to the same receptors. The data available regarding drug-drug interactions is mostly based on case reports and small studies and therefore should be interpreted with caution. The current knowledge is sufficiently strong to guide clinicians in selecting safer drug combinations as summarized here.

Impact of chronic medications in the perioperative period: mechanisms of action and adverse drug effects (Part I)

Background: This review article discusses the pharmacology of the most commonly used chronic medications in patients undergoing elective surgical procedures. The mechanism of action and adverse side effects of cardiovascular medications (e.g., beta blockers, alpha-2 agonist, calcium channel blockers, ACE inhibitors, diuretics), lipid-lowering drugs, gastrointestinal medications (H2-blockers, proton pump inhibitors), pulmonary medications (inhaled β-agonists, anticholinergics,), antibiotics (tetracyclines, clindamycin and macrolide, linezolid), opioids and non-opioids analgesics (NSAIDs, COX-2 inhibitors, acetaminophen), gabapentanoids, erectile dysfunction (ED) drugs, and psychotropic drugs (tricyclic antidepressants [TCAs], monoamine oxidase inhibitors [MAOI], selective serotonin reuptake inhibitors [SSRIs], serotonin norepinephrine reuptake inhibitors [SNRIs], and cannabinol-containing drugs) will be reviewed.Materials and Methods: An online search was conducted from January 2000 through February 2021 with the Medline database through PubMed and Google Scholar using the following search terms/keywords: "chronic medications in the perioperative period", and "chronic medications and anesthetic implications." In addition, we searched for anesthetic side effects associated with the major drug groups.Results and Conclusions: An understanding of the pharmacology and pharmacokinetics of most used chronic medications is important to avoid untoward outcomes in the perioperative period. These drug interactions may result in altered efficacy and toxicity of the anesthetic medications administered during surgery. These drug-drug interactions can also effect the morbidity, mortality, and recovery time of surgical patients. Part I of this two-part review article focuses on the mechanisms of action and adverse side effects of the chronic medications most commonly taken by surgical patients in the preoperative period.

An overview of diagnosis and management of drug-induced hypomagnesemia

Magnesium (Mg) is commonly addressed as the "forgotten ion" in medicine. Nonetheless, hypomagnesemia should be suspected in clinical practice in patients with relevant symptomatology and also be considered a predisposing factor for the development of other electrolyte disturbances. Furthermore, chronic hypomagnesemia has been associated with diabetes mellitus and cardiovascular disease. Hypomagnesemia as a consequence of drug therapy is relatively common, with the list of drugs inducing low serum Mg levels expanding. Culprit medications linked to hypomagnesemia include antibiotics (e.g. aminoglycosides, amphotericin B), diuretics, antineoplastic drugs (cisplatin and cetuximab), calcineurin inhibitors, and proton pump inhibitors. In recent years, the mechanisms of drug-induced hypomagnesemia have been unraveled through the discovery of key Mg transporters in the gut and kidney. This narrative review of available literature focuses on the pathogenetic mechanisms underlying drug-induced hypomagnesemia in order to increase the insight of clinicians toward early diagnosis and effective management.

Analysis of Global Oxidative Status Using Multimarker Scores Reveals a Specific Association Between Renal Dysfunction and Diuretic Therapy in Older Adults

Aging and chronic kidney disease (CKD) are important interrelated cardiovascular risk (CVR) factors linked to oxidative stress, but this relationship has not been well studied in older adults. We assessed the global oxidative status in an older population with normal to severely impaired renal function. We determined the oxidative status of 93 older adults (mean age 85 years) using multimarker scores. OxyScore was computed as index of systemic oxidative damage by analyzing carbonyl groups, oxidized low-density lipoprotein, 8-hydroxy-2'-deoxyguanosine, and xanthine oxidase activity. AntioxyScore was computed as index of antioxidant defense by analyzing catalase and superoxide dismutase (SOD) activity and total antioxidant capacity. OxyScore and AntioxyScore were higher in subjects with estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 than in peers with eGFR >60 mL/min/1.73 m2, with protein carbonyls, catalase, and SOD activity as major drivers. Older adults with a recent cardiovascular event had similar OxyScore and AntioxyScore as peers with eGFR >60 mL/min/1.73 m2. Multivariate linear regression analysis revealed that both indices were associated with decreased eGFR independently of traditional CVR factors. Interestingly, AntioxyScore was also associated with diuretic treatment, and a more pronounced increase was seen in subjects receiving combination therapy. The associations of AntioxyScore with diuretic treatment and eGFR were mutually independent. In conclusion, eGFR is the major contributor to the imbalance in oxidative stress in this older population. Given the association between oxidative stress, CKD, and CVR, the inclusion of renal function parameters in CVR estimators for older populations, such as the SCORE-OP, might improve their modest performance.

The pharmacotherapeutic management of hyperkalemia in patients with cardiovascular disease

Introduction: Patients with cardiovascular diseases (CVD) are at increased risk of hyperkalemia, particularly when treated with renin-angiotensin-aldosterone inhibitors (RAASIs). Because the occurrence or fear of hyperkalemia, RAASIs are frequently down-titrated or discontinued in patients with CVD, with consequent worse outcomes than patients who remain on maximum doses.Areas covered: This article reviews potassium homeostasis, epidemiology, risk factors, and outcomes of hyperkalemia, and efficacy and safety of the drugs used for acute and chronic treatment of hyperkalemia. A literature search was carried out using the PubMed and guidelines for the management of hyperkalemia.Expert opinion: The emergency treatment of hyperkalemia is not supported by high-quality evidence and clinical trials did not report drug effects on clinical outcomes. Two potassium binders, patiromer and sodium zirconium cyclosilicate, represent a new approach in the treatment of chronic hyperkalemia as they may allow the titration and maintenance of guidelines-recommended doses of RAASIs in patients with CVD who otherwise would not tolerate them due to the risk of hyperkalemia.Further studies are needed to evaluate the safety and efficacy of drug therapy and support the development of guidelines for acute and chronic hyperkalemia.

Involvement of Muscarinic Receptors in Hypotensive and Diuretic Effects of Aqueous Soluble Fraction from Asphodelus tenuifolius Cav

Background. Asphodelus tenuifolius Cav. (Asphodelaceae) is widely used in Pakistan traditional medicine as a hypotensive and diuretic agent. Despite the cardioprotective effects described for A. tenuifolius, the mechanisms involved in its probable hypotensive and diuretic effects have never been evaluated. Firstly, different extracts from A. tenuifolius seeds were obtained, and their antioxidant profiles and chemical constituents by LC-DAD-were determined, including molecular networking by the GNPS platform. Then, to evaluate changes in blood pressure, different groups of anesthetized normotensive rats were intravenously treated with the crude extract (AT-Cr, 1-50 mg/kg), aqueous (AS-AT, 1-25 mg/kg), n-butanol (BS-AT, 1-50 mg/kg), and dichloromethane fraction (DS-AT, 1-80 mg/kg). The diuretic effects of AT-Cr, AS-AT, BS-AT, and DS-AT at 100, 200, and 300 mg/kg, p.o. doses, were also evaluated in comparison with hydrochlorothiazide (HCTZ, 10 mg/kg, p.o). The urinary volume, sodium, potassium, and pH were estimated in the sample collected for 6 h from saline-loaded rats. Using pharmacological antagonists or inhibitors, we determine the involvement of acetylcholine, prostaglandins, and nitric oxide in A. tenuifolius-induced hypotensive and diuresis action. In addition, the activities of angiotensin-converting enzyme, erythrocyte carbonic anhydrase, and renal Na+/K+/ATPase were evaluated in vitro. Acute treatment with crude extract and fractions of A. tenuifolius exhibited significant hypotensive and diuretic potential in normotensive rats. However, AS-AT produced the most potent and significant dose-dependent hypotension and diuretic effects in normotensive rats. Previous treatment with atropine significantly reduced the hypotensive and diuretic action of AS-AT, but pretreatment with indomethacin or L-NAME did not affect these effects. Moreover, the 7-day treatment with AS-AT did not reduce activities of serum angiotensin-converting enzyme, erythrocyte carbonic anhydrase, and renal Na+/K+/ATPase. AS-AT showed four major compound node clusters, which included sugars, alkaloids, nucleoside, amino acid, and glycosylated flavonoids. This research supports and extends the traditional use of A. tenuifolius as a hypotensive and diuretic agent. The results showed that AS-AT from A. tenuifolius could present compounds responsible for hypotensive and diuretic activities through the activation of muscarinic receptors.

Contribution of Uptake and Efflux Transporters to Oral Pharmacokinetics of Furosemide

Furosemide is a widely used diuretic for treating excessive fluid accumulation caused by disease conditions like heart failure and liver cirrhosis. Furosemide tablet formulation exhibits variable pharmacokinetics (PK) with bioavailability ranging from 10 to almost 100%. To explain the variable absorption, we integrated the physicochemical, in vitro dissolution, permeability, distribution, and the elimination parameters of furosemide in a physiologically-based pharmacokinetic (PBPK) model. Although the intravenous PBPK model reasonably described the observed in vivo PK data, the reported low passive permeability failed to capture the observed data after oral administration. To mechanistically justify this discrepancy, we hypothesized that transporter-mediated uptake contributes to the oral absorption of furosemide in conjunction with passive permeability. Our in vitro results confirmed that furosemide is a substrate of intestinal breast cancer resistance protein (BCRP), multidrug resistance-associated protein 4 (MRP4), and organic anion transporting polypeptide 2B1 (OATP2B1), but it is not a substrate of P-glycoprotein (P-gp) and MRP2. We then estimated the net transporter-mediated intestinal uptake and integrated it into the PBPK model under both fasting and fed conditions. Our in vitro data and PBPK model suggest that the absorption of furosemide is permeability-limited, and OATP2B1 and MRP4 are important for its permeability across intestinal membrane. Further, as furosemide has been proposed as a probe substrate of renal organic anion transporters (OATs) for assessing clinical drug-drug interactions (DDIs) during drug development, the confounding effects of intestinal transporters identified in this study on furosemide PK should be considered in the clinical transporter DDI studies.

Organ protection by SGLT2 inhibitors: role of metabolic energy and water conservation

Therapeutic inhibition of the sodium-glucose co-transporter 2 (SGLT2) leads to substantial loss of energy (in the form of glucose) and additional solutes (in the form of Na⁺ and its accompanying anions) in urine. However, despite the continuously elevated solute excretion, long-term osmotic diuresis does not occur in humans with SGLT2 inhibition. Rather, patients on SGLT2 inhibitor therapy adjust to the reduction in energy availability and conserve water. The metabolic adaptations that are induced by SGLT2 inhibition are similar to those observed in aestivation - an evolutionarily conserved survival strategy that enables physiological adaptation to energy and water shortage. Aestivators exploit amino acids from muscle to produce glucose and fatty acid fuels. This endogenous energy supply chain is coupled with nitrogen transfer for organic osmolyte production, which allows parallel water conservation. Moreover, this process is often accompanied by a reduction in metabolic rate. By comparing aestivation metabolism with the fuel switches that occur during therapeutic SGLT2 inhibition, we suggest that SGLT2 inhibitors induce aestivation-like metabolic patterns, which may contribute to the improvements in cardiac and renal function observed with this class of therapeutics.

Impact of plasma potassium normalization on short-term mortality in patients with hypertension and hypokalemia or low normal potassium

Background

Hypokalemia is common in patients treated with antihypertensive drugs, but the impact of correcting hypokalemia is insufficiently studied. We examined the consequences of hypokalemia and borderline hypokalemia correction in patients with hypertension.

Methods

We identified 8976 patients with hypertension and plasma potassium concentrations ≤3.7 mmol/L within 100 days from combination antihypertensive therapy initiation. The first measurement between 6 and 100 days after the episode with potassium ≤3.7 mmol/L was retained. We investigated all-cause and cardiovascular mortality within 60-days from the second potassium measurement using Cox regression. Mortality was examined for seven predefined potassium intervals derived from the second measurement: 1.5–2.9 mmol/L (n = 271), 3.0–3.4 mmol/L (n = 1341), 3.5–3.7 (n = 1982) mmol/L, 3.8–4.0 mmol/L (n = 2398, reference), 4.1–4.6 mmol/L (n = 2498), 4.7–5.0 mmol/L (n = 352) and 5.1–7.1 mmol/L (n = 134).

Results

Multivariable analysis showed that potassium concentrations 1.5–2.9 mmol/L, 3.0–3.4 mmol/L, 4.7–5.0 mmol/L and 5.1–7.1 mmol/L were associated with increased all-cause mortality (HR 2.39, 95% CI 1.66–3.43; HR 1.36, 95% CI 1.04–1.78; HR 2.36, 95% CI 1.68–3.30 and HR 2.62, 95% CI 1.73–3.98, respectively). Potassium levels <3.0 and > 4.6 mmol/L were associated with increased cardiovascular mortality. The adjusted standardized 60-day mortality risks in the seven strata were: 11.7% (95% CI 8.3–15.0%), 7.1% (95% CI 5.8–8.5%), 6.4% (95% CI 5.3–7.5%), 5.4% (4.5–6.3%), 6.3% (5.4–7.2%), 11.6% (95% CI 8.7–14.6%) and 12.6% (95% CI 8.2–16.9%), respectively.

Conclusions

Persistent hypokalemia was frequent and associated with increased all-cause and cardiovascular mortality. Increase in potassium to levels > 4.6 mmol/L in patients with initial hypokalemia or low normal potassium was associated with increased all-cause and cardiovascular mortality.

Furosemide and spironolactone doses and hyponatremia in patients with heart failure

Background

Hyponatremia, a marker of disease severity and prognosis, has been associated with various clinical factors and drug use, especially diuretics.

Methods

This observational prospective cohort study enrolled patients hospitalized at the University Hospital Center Split because of heart failure (HF). We investigated the association of clinical variables and cardiovascular drugs, including furosemide, hydrochlorothiazide, spironolactone, and their doses, with the presence of hyponatremia at admission.

Results

Of the 565 included patients, 32.4% were hyponatremic, 62.6% were males, and the mean age was 73.1 ± 10.6 years. In the univariate analysis, hyponatremic patients were more often current smokers (p = 0.01), alcohol consumers (p = 0.01), receiving spironolactone (p = 0.004) or combination of furosemide and spironolactone (p = 0.003). Patients who received 50 and 100 mg of spironolactone, compared to those receiving 25 mg (p < 0.0001), as well as patients who received 250 to 500 mg of furosemide compared to ≤240 mg (p = 0.001), were significantly more often hyponatremic. In the multivariate analysis, when diuretic doses were accounted for, furosemide doses of 250 to 500 mg (p = 0.009), spironolactone doses of 50 to 100 mg (p = 0.0003), increasing age (p = 0.03), diabetes mellitus (p = 0.02) and alcohol consumption (p = 0.04) were independently associated with hyponatremia.

Conclusion

High doses of furosemide and spironolactone, or concomitant use of these diuretics, seem to be an important cause of hyponatremia in HF patients, particularly in combination with advanced age, diabetes and alcohol consumption. Diuretic dose reduction may help avoid hyponatremia and improve clinical status and prognosis in such patients.

The Role of Magnesium in the Development of Cardiovascular Diseases and the Possibility of their Prevention and Correction with Magnesium Preparations (Part 2)

Data on the effect of magnesium on the homeostasis of the body and on the cardiovascular system, are presented in the article. These data supplement information on studies of the role of magnesium in many body processes. The influence of lifestyle on magnesium metabolism, the pathological processes that cause its deficiency, and the clinical picture of hypomagnesemia are presented in the article. The necessary daily amount of magnesium, ways to restore the magnesium deficiency, both nutritional and with the help of magnesium-containing pharmacological preparations, their form, bioavailability and dosage regimen are discussed. Diseases that occur and/or worsen with hypomagnesemia are considered. Data on the iatrogenic effect of many drugs, including cardiological, removing magnesium from the body and ways to solve this issue, are also presented. Hypomagnesemia exacerbates the course of cardiovascular disease. Elimination of magnesium deficiency can contribute a lot to the prevention of morbidity and the optimization of treatment of patients.

Role of the NO/cGMP pathway and renin-angiotensin system in the hypotensive and diuretic effects of aqueous soluble fraction from Crataegus songarica K. Koch

ETHNO-PHARMACOLOGICAL RELEVANCE

Fruits of Crataegus songarica K. Koch. (Rosaceae) are commonly used in folk medicine for their diuretic properties to treat hypertension and congestive heart failure. To date, no scientific data has been published to support the diuretic potential.

AIM OF THE STUDY

The purpose of this study was to evaluate efficacy and mechanism underlying the hypotensive and diuretic action of C. songarica in normotensive rats and to determine the constituents from the extracts by LC-DAD-MS.

MATERIALS AND METHODS

Firstly, phytochemical profiling and antioxidant potential of C. songarica extracts was determined. Then, to evaluate changes in blood pressure, different groups of anesthetized normotensive rats were intravenously treated with crude extract (CS-Cr, 10-80 mg/kg), aqueous soluble (AS-CS, 0.1-20 mg/kg), and n-butanol soluble fractions of C. songarica (BS-CS, 1-80 mg/kg). The diuretic effects of CS-Cr (100-500 mg/kg, p.o), AS-CS (100-300 mg/kg, p.o) and BS-CS (100-300 mg/kg, p.o) were evaluated in comparison with hydrochlorothiazide (HCTZ, 10 mg/kg, p.o). The urinary volume, sodium, potassium and pH were estimated in the sample collected for 6 h from saline-loaded rats. Using pharmacological antagonists or inhibitors, we determine the involvement of acetylcholine, prostaglandins, and nitric oxide in C. songarica induced hypotensive and diuresis action. In addition, the activities of angiotensin converting enzyme, erythrocytary carbonic anhydrase and renal Na+/K+/ATPase were evaluated in vitro.

RESULTS

From the LC-DAD-MS analyses, thirty-nine compounds were detected, showing a complex chemical profile and an expressive antioxidant activity "in vitro". Acute treatment with CS-Cr, AS-CS, and BS-CS exhibited significant hypotensive and diuretic potential in normotensive rats. However, AS-CS produced most potent and significant dose-dependent hypotension in normotensive rats, and also produced highly significant diuretic and saluretic effects. Despite the changes in urinary excretion of electrolytes, the plasmatic levels of sodium and potassium were not changed. Previous treatment with atropine and L-NAME significantly reduced the hypotensive and diuretic action of AS-CS in normotensive rats. Moreover, the 7-day treatment with AS-CS also resulted in significant ACE inhibitory activity.

CONCLUSION

This research supports and extends the ethnomedicinal use of C. songarica as diuretic and hypotensive agent. The results showed that AS-CS from C. songarica could present compounds responsible for hypotensive and diuretic activities with no signs of toxicity, and these effects could involve nitric oxide pathway activated by muscarinic receptors or/and inhibition of angiotensin converting enzyme.

Renal tubular effects of prolonged therapy with the GLP-1 receptor agonist lixisenatide in patients with type 2 diabetes mellitus

Glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) are well-established glucose-lowering drugs for type 2 diabetes mellitus (T2DM) management. Acute GLP-1RA administration increases urinary excretion of sodium and other electrolytes. However, the renal tubular effects of prolonged GLP-1RA treatment are largely unknown. In this secondary analysis of a randomized trial, we determined the renal tubular effects of 8-wk treatment with 20 μg lixisenatide, a short-acting (prandial) GLP-1RA, versus titrated once-daily insulin glulisine in 35 overweight T2DM-patients on stable insulin glargine background therapy (age: 62 ± 7 yr, glycated hemoglobin: 8.0 ± 0.9%, estimated glomerular filtration rate: >60 ml·min^-1·1.73 m^-2). After a standardized breakfast, lixisenatide increased absolute and fractional excretions of sodium, chloride, and potassium and increased urinary pH. In contrast, lixisenatide reduced absolute and fractional excretions of magnesium, calcium, and phosphate. At week 8, patients treated with lixisenatide had significantly more phosphorylated sodium-hydrogen exchanger isoform 3 (NHE3) in urinary extracellular vesicles than those on insulin glulisine treatment, which suggested decreased NHE3 activity in the proximal tubule. A rise in postprandial blood pressure with lixisenatide partly explained the changes in the urinary excretion of sodium, potassium, magnesium, and phosphate and the changes in urinary pH. In conclusion, lixisenatide affects postprandial urinary excretion of several electrolytes and increases urinary pH compared with insulin glulisine in T2DM patients after 8 wk of treatment. This is most likely explained by a drug-induced rise in blood pressure or direct inhibitory effects on NHE3 in the proximal tubule.

Kir Channel Blockages by Proflavine Derivatives via Multiple Modes of Interaction

Many compounds inhibit tetrameric and pseudo-tetrameric cation channels by associating with the central cavity located in the middle of the membrane plane. They traverse the ion conduction pathway from the intracellular side and through access to the cavity. Previously, we reported that the bacteriostatic agent, proflavine, preferentially blocked a subset of inward rectifier K⁺ (Kir) channels. However, the development of the inhibition of Kir1.1 by the compound was obviously different from that operating in Kir3.2 as a pore blocker. To gain mechanistic insights into the compound-channel interaction, we analyzed its chemical specificity, subunit selectivity, and voltage dependency using 13 different combinations of Kir-channel family members and 11 proflavine derivatives. The Kir-channel family members were classified into three groups: 1) Kir2.2, Kir3.x, Kir4.2, and Kir6.2Δ36, which exhibited Kir3.2-type inhibition (slow onset and recovery, irreversible, and voltage-dependent blockage); 2) Kir1.1 and Kir4.1/Kir5.1 (prompt onset and recovery, reversible, and voltage-independent blockage); and 3) Kir2.1, Kir2.3, Kir4.1, and Kir7.1 (no response). The degree of current inhibition depended on the combination of compounds and channels. Chimera between proflavine-sensitive Kir1.1 and -insensitive Kir4.1 revealed that the extracellular portion of Kir1.1 is crucial for the recognition of the proflavine derivative acrinol. In conclusion, preferential blockage of Kir-channel family members by proflavine derivatives is based on multiple modes of action. This raises the possibility of designing subunit-specific inhibitors.

Model based population PK-PD analysis of furosemide for BP lowering effect: A comparative study in primary and secondary hypertension

Though numerous reports have demonstrated multiple mechanisms by which furosemide can exert its anti-hypertensive response. However, lack of studies describing PK-PD relationship for furosemide featuring its anti-hypertensive property has limited its usage as a blood pressure (BP) lowering agent. Serum concentrations and mean arterial BP were monitored following 40 and 80mgkg^-1 multiple oral dose of furosemide in spontaneously hypertensive rats (SHR) and DOCA-salt induced hypertensive (DOCA-salt) rats. A simultaneous population PK-PD relationship using E_max model with effect compartment was developed to compare the anti-hypertensive efficacy of furosemide in these rat models. A two-compartment PK model with Weibull-type absorption and first-order elimination best described the serum concentration-time profile of furosemide. In the present study, post dose serum concentrations of furosemide were found to be lower than the EC₅₀. The EC₅₀ predicted in DOCA-salt rats was found to be lower (4.5-fold), whereas the tolerance development was higher than that in SHR model. The PK-PD parameter estimates, particularly lower values of EC₅₀, K_e and Q in DOCA-salt rats as compared to SHR, pinpointed the higher BP lowering efficacy of furosemide in volume overload induced hypertensive conditions. Insignificantly altered serum creatinine and electrolyte levels indicated a favorable side effect profile of furosemide. In conclusion, the final PK-PD model described the data well and provides detailed insights into the use of furosemide as an anti-hypertensive agent.

Management of Hypertension in Patients with Chronic Kidney Disease

Hypertension is the leading factor in the global burden of disease. It is the predominant modifiable risk factor for stroke, heart disease, and kidney failure. Chronic kidney disease (CKD) is both a common cause and sequel of uncontrolled hypertension. The pathophysiology of CKD-associated hypertension is complex and multi-factorial. This paper reviews the key pathogenic mechanisms of CKD-associated hypertension, the importance of standardized blood pressure (BP) measurement in establishing the diagnosis and management plus the significance of ambulatory BP monitoring for assessment of diurnal BP variation commonly seen in CKD. The optimal BP target in CKD remains a matter of discussion despite recent clinical trials. Medical therapy can be difficult and challenging. In addition to lifestyle modification and dietary salt restriction, treatment may need to be individualized based on co-morbidities. Combination of antihypertensive drugs, including appropriate diuretic choice and dose, is of great significance in hypertension management in CKD.

Diuretics in the treatment of hypertension

Diuretics have long been used for the treatment of hypertension. Thiazide diuretics are the most commonly prescribed diuretics for hypertension, but other classes of diuretics may be useful in alternative circumstances. Although diuretics are no longer considered the preferred agent for treatment of hypertension in adults and children, they remain acceptable first-line options. Diuretics effectively decrease blood pressure in hypertensive patients, and in adults with hypertension reduce the risk of adverse cardiovascular outcomes. Because of varied pharmacokinetic and pharmacodynamic differences, chlorthalidone may be the preferred thiazide diuretic in the treatment of primary hypertension. Other types of diuretics (e.g., loop, potassium sparing) may be useful for the treatment of hypertension related to chronic kidney disease (CKD) and other varied conditions. Common side effects of thiazides are mostly dose-related and involve electrolyte and metabolic abnormalities.

Pharmacological reasons that may explain why randomized clinical trials have failed in acute heart failure syndromes

Acute heart failure (AHF) represents a clinical challenge as it encloses a heterogeneous group of syndromes (AHFS) with different pathophysiology, clinical presentations, prognosis and response to therapy. In the last 25years multiple therapeutic targets have been identified and numerous new drugs were evaluated but, up to now, all failed to demonstrate a consistent benefit on clinical outcomes. Moreover, a repeated finding has been the poor correlation between the encouraging results of preclinical and early clinical trials and the lack of effect on outcomes observed in phase III trials. We review several possible pharmacological reasons that may explain the lack of success to develop new drugs and the pharmacological challenges to overcome in the future to develop new more effective and safer drugs for the treatment of AHFS.

Adverse safety events in patients with Chronic Kidney Disease (CKD)

INTRODUCTION

Chronic kidney disease (CKD) confers a higher risk of adverse safety events as a result of many factors including medication dosing errors and use of nephrotoxic drugs, which can cause kidney injury and renal function decline. CKD patients may also have comorbidities such as hypertension and diabetes for which they require more frequent care from different providers, and for which standard, but countervailing treatments, may put them at risk for adverse safety events. Areas covered: In addition to the well-known agents such as iodinated radiocontrast, antimicrobials, diuretics and angiotensin converting enzyme (ACE) inhibitors which can directly affect renal function, safety considerations in the treatment of common CKD complications such as anemia, diabetes, analgesia and thrombosis will also be discussed. Expert opinion: Better outcomes in CKD may be achieved by alerting care providers to the special care needs of kidney patients and encouraging patients to self-manage their disease with the decision support of multidisciplinary patient care teams.

Loop Diuretics in the Treatment of Hypertension

Loop diuretics are not recommended in current hypertension guidelines largely due to the lack of outcome data. Nevertheless, they have been shown to lower blood pressure and to offer potential advantages over thiazide-type diuretics. Torsemide offers advantages of longer duration of action and once daily dosing (vs. furosemide and bumetanide) and more reliable bioavailability (vs. furosemide). Studies show that the previously employed high doses of thiazide-type diuretics lower BP more than furosemide. Loop diuretics appear to have a preferable side effect profile (less hyponatremia, hypokalemia, and possibly less glucose intolerance). Studies comparing efficacy and side effect profiles of loop diuretics with the lower, currently widely prescribed, thiazide doses are needed. Research is needed to fill gaps in knowledge and common misconceptions about loop diuretic use in hypertension and to determine their rightful place in the antihypertensive arsenal.

Hypertension in Chronic Kidney Disease

Hypertension, a global public health problem, is currently the leading factor in the global burden of disease. It is the major modifiable risk factor for heart disease, stroke and kidney failure. Chronic kidney disease (CKD) is both a common cause of hypertension and CKD is also a complication of uncontrolled hypertension. The interaction between hypertension and CKD is complex and increases the risk of adverse cardiovascular and cerebrovascular outcomes. This is particularly significant in the setting of resistant hypertension commonly seen in patient with CKD. The pathophysiology of CKD associated hypertension is multi-factorial with different mechanisms contributing to hypertension. These pathogenic mechanisms include sodium dysregulation, increased sympathetic nervous system and alterations in renin angiotensin aldosterone system activity. Standardized blood pressure (BP) measurement is essential in establishing the diagnosis and management of hypertension in CKD. Use of ambulatory blood pressure monitoring provides an additional assessment of diurnal variation in BP commonly seen in CKD patients. The optimal BP target in the treatment of hypertension in general and CKD population remains a matter of debate and controversial despite recent guidelines and clinical trial data. Medical therapy of patients with CKD associated hypertension can be difficult and challenging. Additional evaluation by a hypertension specialist may be required in the setting of treatment resistant hypertension by excluding pseudo-resistance and treatable secondary causes. Treatment with a combination of antihypertensive drugs, including appropriate diuretic choice, based on estimated glomerular filtration rate, is a key component of hypertension management in CKD patients. In addition to drug treatment non-pharmacological approaches including life style modification, most important of which is dietary salt restriction, should be included in the management of hypertension in CKD patients.

The double challenge of resistant hypertension and chronic kidney disease

Resistant hypertension is defined as blood pressure above goal despite adherence to a combination of at least three optimally dosed antihypertensive medications, one of which is a diuretic. Chronic kidney disease is the most frequent of several patient factors or comorbidities associated with resistant hypertension. The prevalence of resistant hypertension is increased in patients with chronic kidney disease, while chronic kidney disease is associated with an impaired prognosis in patients with resistant hypertension. Recommended low-salt diet and triple antihypertensive drug regimens that include a diuretic, should be complemented by the sequential addition of other antihypertensive drugs. New therapeutic innovations for resistant hypertension, such as renal denervation and carotid barostimulation, are under investigation especially in patients with advanced chronic kidney disease. We discuss resistant hypertension in chronic kidney disease stages 3-5 (ie, patients with an estimated glomerular filtration rate below 60 mL/min per 1·73 m(2) and not on dialysis), in terms of worldwide epidemiology, outcomes, causes and pathophysiology, evidence-based treatment, and a call for action.

Loop Diuretics in Clinical Practice

Diuretics are commonly used to control edema across various clinical fields. Diuretics inhibit sodium reabsorption in specific renal tubules, resulting in increased urinary sodium and water excretion. Loop diuretics are the most potent diuretics. In this article, we review five important aspects of loop diuretics, in particular furosemide, which must be considered when prescribing this medicine: (1) oral versus intravenous treatment, (2) dosage, (3) continuous versus bolus infusion, (4) application in chronic kidney disease patients, and (5) side effects. The bioavailability of furosemide differs between oral and intravenous therapy. Additionally, the threshold and ceiling doses of furosemide differ according to the particular clinical condition of the patient, for example in patients with severe edema or chronic kidney disease. To maximize the efficiency of furosemide, a clear understanding of how the mode of delivery will impact bioavailability and the required dosage is necessary.