Pharmacology of diuretics

Bumetanide Attenuates Cognitive Deficits and Brain Damage in Rats Subjected to Hypoxia-Ischemia at Two Time Points of the Early Postnatal Period

Neonatal hypoxia-ischemia (HI) is one of the main causes of tissue damage, cell death, and imbalance between neuronal excitation and inhibition and synaptic loss in newborns. GABA, the major inhibitory neurotransmitter of the central nervous system (CNS) in adults, is excitatory at the onset of neurodevelopment and its action depends on the chloride (Cl-) cotransporters NKCC1 (imports Cl-) and KCC2 (exports Cl-) expression. Under basal conditions, the NKCC1/KCC2 ratio decreases over neurodevelopment. Thus, changes in this ratio caused by HI may be related to neurological disorders. The present study evaluated the effects of bumetanide (NKCC cotransporters inhibitor) on HI impairments in two neurodevelopmental periods. Male Wistar rat pups, 3 (PND3) and 11 (PND11) days old, were submitted to the Rice-Vannucci model. Animals were divided into 3 groups: SHAM, HI-SAL, and HI-BUM, considering each age. Bumetanide was administered intraperitoneally at 1, 24, 48, and 72 h after HI. NKCC1, KCC2, PSD-95, and synaptophysin proteins were analyzed after the last injection by western blot. Negative geotaxis, righting reflex, open field, object recognition test, and Morris water maze task were performed to assess neurological reflexes, locomotion, and memory function. Tissue atrophy and cell death were evaluated by histology. Bumetanide prevented neurodevelopmental delay, hyperactivity, and declarative and spatial memory deficits. Furthermore, bumetanide reversed HI-induced brain tissue damage, reduced neuronal death and controlled GABAergic tone, maintained the NKCC1/KCC2 ratio, and synaptogenesis close to normality. Thereby, bumetanide appears to play an important therapeutic role in the CNS, protecting the animals against HI damage and improving functional performance.

Diuretics, SGLT2 inhibitors and falls in older heart failure patients: to prescribe or to deprescribe? A clinical review

PURPOSE

Both heart failure and its treatment with diuretics or SGLT2 inhibitors increase fall risk in older adults. Therefore, decisions to continue or deprescribe diuretics or SGLT2 inhibitors in older heart failure patients who have fallen are generally highly complex and challenging for clinicians. However, a comprehensive overview of information required for rationale and safe decision-making is lacking. The aim of this clinical review was to assist clinicians in safe (de)prescribing of these drug classes in older heart failure patients.

METHODS

We comprehensively searched and summarized published literature and international guidelines on the efficacy, fall-related safety issues, and deprescribing of the commonly prescribed diuretics and SGLT2 inhibitors in older adults.

RESULTS

Both diuretics and SGLT2 inhibitors potentially cause various fall-related adverse effects. Their fall-related side effect profiles partly overlap (e.g., tendency to cause hypotension), but there are also important differences; based on the currently available evidence of this relatively new drug class, SGLT2 inhibitors seem to have a favorable fall-related adverse effect profile compared to diuretics (e.g., low/absent tendency to cause hyperglycemia or electrolyte abnormalities, low risk of worsening chronic kidney disease). In addition, SGLT2 inhibitors have potential beneficial effects (e.g., disease-modifying effects in heart failure, renoprotective effects), whereas diuretic effects are merely symptomatic.

CONCLUSION

(De)prescribing diuretics and SGLT2 inhibitors in older heart failure patients who have fallen is often highly challenging, but this clinical review paper assists clinicians in individualized and patient-centered rational clinical decision-making: we provide a summary of available literature on efficacy and (subclass-specific) safety profiles of diuretics and SGLT2 inhibitors, and practical guidance on safe (de)prescribing of these drugs (e.g. a clinical decision tree for deprescribing diuretics in older adults who have fallen).

Cardiorenal syndrome: Pathophysiology as a key to the therapeutic approach in an under-diagnosed disease

Cardiorenal syndrome is a clinical condition that impacts both the heart and the kidneys. One organ's chronic or acute impairment can lead to the other's chronic or acute dysregulation. The cardiorenal syndrome has been grouped into five subcategories that describe the etiology, pathophysiology, duration, and pattern of cardiac and renal dysfunction. This classification reflects the large spectrum of interrelated dysfunctions and underlines the bidirectional nature of heart-kidney interactions. However, more evidence is needed to apply these early findings in medical practice. Understanding the relationship between these two organs during each organ's impairment has significant clinical implications that are relevant for therapy in both chronic and acute conditions. The epidemiology, definition, classification, pathophysiology, therapy, and outcome of each form of cardiorenal syndrome are all examined in this review.

The Role of Serum Chloride in Acute and Chronic Heart Failure: A Narrative Review

Clinical guidelines include diuretics for the treatment of heart failure (HF), not to decrease mortality but to decrease symptoms and hospitalizations. More attention has been paid to the worse outcomes, including mortality, associated with continual diuretic therapy due to hypochloremia. Studies have revealed a pivotal role for serum chloride in the pathophysiology of HF and is now a target of treatment to decrease mortality. The prognostic value of serum chloride in HF has been the subject of much attention. Mechanistically, the macula densa, a region in the renal juxtaglomerular apparatus, relies on chloride levels to sense salt and volume status. The recent discovery of with-no-lysine (K) (WNK) protein kinase as an intracellular chloride sensor sheds light on the possible reason of diuretic resistance in HF. The action of chloride on WNKs results in the upregulation of the sodium-potassium-chloride cotransporter and sodium-chloride cotransporter receptors, which could lead to increased electrolyte and fluid reabsorption. Genetic studies have revealed that a variant of a voltage-sensitive chloride channel (CLCNKA) gene leads to almost a 50% decrease in current amplitude and function of the renal chloride channel. This variant increases the risk of HF. Several trials exploring the prognostic value of chloride in both acute and chronic HF have shown mostly positive results, some even suggesting a stronger role than sodium. However, so far, interventional trials exploring serum chloride as a therapeutic target have been largely inconclusive. This study is a review of the pathophysiologic effects of hypochloremia in HF, the genetics of chloride channels, and clinical trials that are underway to investigate novel approaches to HF management.

1,3,5,6-tetrahydroxyxanthone promotes diuresis, renal protection and antiurolithic properties in normotensive and hypertensive rats

OBJECTIVES

This study investigated the prolonged diuretic and renal effects of 1,3,5,6- tetrahydroxyxanthone (THX) in rats.

METHODS

Normotensive (NTR) and hypertensive rats (SHR) received orally the treatment with THX, hydrochlorothiazide or vehicle (VEH). Urine volume, urinary, plasma and kidney parameters were evaluated daily or at the end of 7 days of the experiment.

KEY FINDINGS

The urinary volume of both NTR and SHR were significantly augmented with the THX treatment, an effect associated with increased levels of urinary Na+ and K+, besides a Ca2+-sparing effect. As well, THX decreased the quantity of monohydrate crystals in urines from NTR and SHR when compared with VEH-group. Regarding the renal analyses, the glutathione levels and the activities of superoxide dismutase, glutathione S-transferase and myeloperoxidase in kidney homogenates of the SHR group were decreased. In contrast, the generation of lipid hydroperoxides (LOOH) and catalase activity was significantly increased. THX reduced the content of LOOH and increased nitrite levels in kidney homogenates obtained from SHR. Additionally, THX also augmented the levels of nitrite in the plasma from the SHR group.

CONCLUSIONS

Therefore, THX can be highlighted as a natural diuretic agent with renal protective properties and antiurolithic action.

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.

Bumetanide Oral Liquid Formulation for the Treatment of Children and Adolescents with Autism Spectrum Disorder: Design of Two Phase III Studies (SIGN Trials)

There are currently no approved pharmacological treatments to improve social reciprocity and limit repetitive and rigid behaviors in autism spectrum disorder (ASD). We describe the design of two Phase III studies evaluating the efficacy/safety of bumetanide oral liquid formulation in ASD. These are international, multicenter, randomized, double-blind, placebo-controlled studies in children and adolescents with ASD aged 7 to 17 years (n = 200; study 1), or younger children with ASD aged 2 to 6 years (n = 200; study 2). The primary endpoint of each is change in Childhood Autism Rating Scale 2 total raw score after 6 months. These studies could contribute to the first pharmacological treatment to improve social reciprocity and limit repetitive and rigid behaviors in children and adolescents with ASD.

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.

Synthesis and biological evaluation of ethacrynic acid derivatives bearing sulfonamides as potent anti-cancer agents

A series of ethacrynic acid (2-[2,3-dichloro-4-(2-methylidenebutanoyl)phenoxy]acetic acid) (EA, Edecrin) containing sulfonamides linked via three types of linkers namely 1,2-ethylenediamine, piperazine and 4-aminopiperidine was synthesized and subsequently evaluated in vitro against HL60 and HCT116 cancer cell lines. All the EA analogs, excluding 6a and 6c, showed anti-proliferative activity with IC_50s in the micromolar range (less than 4 uM). Three derivatives 6b, 7b and 7e were selected for their interesting dual activity on HL60 cell line in order to be further evaluated against a panel of cancer cell lines (HCT116, A549, MCF7, PC3, U87-MG and SKOV3) as well as on MRC5 as a normal cell line. These compounds displayed IC₅₀ values in nanomolar range against A549, MCF7, PC3 and HCT116 cell lines, deducing the discovery that piperazine or 4-aminopiperidine is the linker's best choice to develop EA analogs with highly potent anti-proliferative activities own up to 24 nM. Besides, in terms of selectivity, those linkers are more suitable offering safety ratios of up to 63.8.

Enhancing the solubility and permeability of the diuretic drug furosemide via multicomponent crystal forms

Furosemide (FSM) is a biopharmaceutical classification system (BCS) class IV drug, being a potent loop diuretic used in the treatment of congestive heart failure and edema. Due to its low solubility and permeability, FSM is known for exhibiting poor oral bioavailability. In order to overcome or even minimize these undesirable biopharmaceutical attributes, in this work we have focused on the development of more soluble and permeable multicomponent solid forms of FSM. Using solvent evaporation as crystallization method, a salt and a cocrystal of FSM with imidazole (IMI) and 5-fluorocytosine (5FC) coformers, named FSM-IMI and FSM-5FC, respectively, were successfully prepared. A detailed structural study of these new solid forms was conducted using single and powder X-ray diffraction (SCXRD, PXRD), Fourier Transform Infrared (FT-IR) and proton Nuclear Magnetic Resonance (¹H NMR) spectroscopy and thermal analysis (thermogravimetry, differential scanning calorimetry and hot-stage microscopy). Both FSM-IMI and FSM-5FC showed substantial enhancements in the solubility (up 118-fold), intrinsic dissolution (from 1.3 to 2.6-fold) and permeability (from 2.1 to 2.8-fold), when compared to the pure FSM. These results demonstrate the potential of these new solid forms to increase the limited bioavailability of FSM.

Use of QT Prolonging Medications by Hemodialysis Patients and Individuals Without End-Stage Kidney Disease

Background The rate of sudden cardiac death in the hemodialysis population exceeds that of the general population by >20-fold. Hemodialysis patients may be particularly susceptible to sudden cardiac death provoked by drug-induced QT prolongation because of their substantial cardiovascular disease burden, exposure to electrolyte shifts during dialysis, and extensive polypharmacy. However, population-specific data regarding the frequency and patterns of QT prolonging medication use are limited. Methods and Results We conducted a descriptive drug utilization study using 3 administrative databases, the United States Renal Data System, MarketScan, and Medicare claims. We characterized the extent and patterns of QT prolonging medication use by adult hemodialysis patients and individuals without end-stage kidney disease annually from 2012 to 2016. We also identified instances of high-risk QT prolonging medication use among hemodialysis patients. In total, 338 515 hemodialysis patients and 40.7 million individuals without end-stage kidney disease were studied. Annual utilization rates of QT prolonging medications with known torsades de pointes risk in hemodialysis patients were ~1.4 to ~2.5 times higher than utilization rates in individuals without end-stage kidney disease. Hemodialysis patients with demographic and clinical risk factors for drug-induced QT prolongation were exposed to medications with known torsades de pointes risk more often than patients without risk factors. Conclusions Hemodialysis patients use QT prolonging medications with known torsades de pointes risk more extensively than individuals without end-stage kidney disease. Given the widespread use and instances of high-risk prescribing, future studies evaluating the cardiac safety of these drugs in the hemodialysis population are needed.

Evaluation of a Common Prescribing Cascade of Calcium Channel Blockers and Diuretics in Older Adults With Hypertension

IMPORTANCE

Calcium channel blockers (CCBs) are commonly prescribed agents for hypertension that can cause peripheral edema. A prescribing cascade occurs when the edema is misinterpreted as a new medical condition and a diuretic is subsequently prescribed to treat the edema. The extent to which this prescribing cascade occurs at a population level is not well understood.

OBJECTIVE

To measure the association between being newly dispensed a CCB and subsequent dispensing of a loop diuretic in older adults with hypertension.

DESIGN, SETTING, AND PARTICIPANTS

A population-based cohort study was performed using linked health administrative databases of community-dwelling adults 66 years or older with hypertension and new prescription drug claims from September 30, 2011, to September 30, 2016, in Ontario, Canada. The dates of analysis were September 1, 2018, to May 30, 2019.

EXPOSURES

Individuals who were newly dispensed a CCB were compared with the following 2 groups: (1) individuals who were newly dispensed an angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker and (2) individuals who were newly dispensed an unrelated medication.

MAIN OUTCOMES AND MEASURES

Hazard ratios (HRs) with 95% CIs were estimated for individuals who were dispensed a loop diuretic within 90 days of follow-up using Cox proportional hazards regression models.

RESULTS

The cohort included 41 086 older adults (≥66 years) with hypertension who were newly dispensed a CCB, 66 494 individuals who were newly dispensed another antihypertensive medication, and 231 439 individuals who were newly dispensed an unrelated medication. At index (ie, the dispensing date), the mean (SD) age was 74.5 (6.9) years, and 191 685 (56.5%) were women. Individuals who were newly dispensed a CCB had a higher cumulative incidence at 90 days of being dispensed a loop diuretic than individuals in both control groups (1.4% vs 0.7% and 0.5%, P < .001). After adjustment, individuals who were newly dispensed a CCB had increased relative rates of being dispensed a loop diuretic compared with individuals who were newly dispensed an angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker (HR, 1.68; 95% CI, 1.38-2.05 in the first 30 days after index [days 1-30]; 2.26; 95% CI, 1.76-2.92 in the subsequent 30 days [days 31-60]; and 2.40; 95% CI, 1.84-3.13 in the third month of follow-up [days 61-90]) and individuals who were newly dispensed unrelated medications (HR, 2.51; 95% CI, 2.13-2.96 for 1-30 days after index; 2.99; 95% CI, 2.43-3.69 for 31-60 days after index; and 3.89; 95% CI, 3.11-4.87 for 61-90 days after index). This association persisted, although slightly attenuated, from 90 days to up to 1 year of follow-up and when restricted to a subgroup of individuals who were newly dispensed amlodipine.

CONCLUSIONS AND RELEVANCE

Many older adults with hypertension who are newly dispensed a CCB subsequently receive a loop diuretic. Given how widely CCBs are prescribed, interventions are needed to raise clinicians' awareness of this common prescribing cascade to reduce the prescribing of potentially unnecessary medications that may cause harm.

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.

Off-Label Use of Bumetanide for Brain Disorders: An Overview

Bumetanide (BTN or BUM) is a FDA-approved potent loop diuretic (LD) that acts by antagonizing sodium-potassium-chloride (Na-K-Cl) cotransporters, NKCC1 (SLc12a2) and NKCC2. While NKCC1 is expressed both in the CNS and in systemic organs, NKCC2 is kidney-specific. The off-label use of BTN to modulate neuronal transmembrane Cl⁻ gradients by blocking NKCC1 in the CNS has now been tested as an anti-seizure agent and as an intervention for neurological disorders in pre-clinical studies with varying results. BTN safety and efficacy for its off-label use has also been tested in several clinical trials for neonates, children, adolescents, and adults. It failed to meet efficacy criteria for hypoxic-ischemic encephalopathy (HIE) neonatal seizures. In contrast, positive outcomes in temporal lobe epilepsy (TLE), autism, and schizophrenia trials have been attributed to BTN in studies evaluating its off-label use. NKCC1 is an electroneutral neuronal Cl⁻ importer and the dominance of NKCC1 function has been proposed as the common pathology for HIE seizures, TLE, autism, and schizophrenia. Therefore, the use of BTN to antagonize neuronal NKCC1 with the goal to lower internal Cl⁻ levels and promote GABAergic mediated hyperpolarization has been proposed. In this review, we summarize the data and results for pre-clinical and clinical studies that have tested off-label BTN interventions and report variable outcomes. We also compare the data underlying the developmental expression profile of NKCC1 and KCC2, highlight the limitations of BTN’s brain-availability and consider its actions on non-neuronal cells.

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.

A pharmacogenetic investigation of intravenous furosemide in decompensated heart failure: a meta-analysis of three clinical trials

We conducted a meta-analysis of pharmacogenomic substudies of three randomized trials conducted in patients with decompensated heart failure (HF) that were led by National Heart Lung and Blood Institute (NHLBI)-funded HF Network to test the hypothesis that candidate genes modulate net fluid loss and weight change in patients with decompensated HF treated with a furosemide-based diuretic regimen. Although none of the genetic variants previously shown to modulate the effects of loop diuretics in healthy individuals were associated with net fluid loss after 72 h of treatment, a set of rare variants in the APOL1 gene, which codes for apolipoprotein L1 (P=0.0005 in the random effects model), was associated with this end point. Moreover, a common variant in the multidrug resistance protein-4 coding gene (ABCC4, rs17268282) was associated with weight loss with furosemide use (P=0.0001). Our results suggest that both common and rare genetic variants modulate the response to a furosemide-based diuretic regimen in patients with decompensated HF.

Pulmonary Oedema-Therapeutic Targets

Pulmonary oedema (PO) is a common manifestation of acute heart failure (AHF) and is associated with a high-acuity presentation and with poor in-hospital outcomes. The clinical picture of PO is dominated by signs of pulmonary congestion, and its pathogenesis has been attributed predominantly to an imbalance in Starling forces across the alveolar-capillary barrier. However, recent studies have demonstrated that PO formation and resolution is critically regulated by active endothelial and alveolar signalling. PO represents a medical emergency and treatment should be individually tailored to the urgency of the presentation and acute haemodynamic characteristics. Although, the majority of patients admitted with PO rapidly improve as result of conventional intravenous (IV) therapies, treatment of PO remains largely opinion based as there is a general lack of good evidence to guide therapy. Furthermore, none of these therapies showed simultaneous benefit for symptomatic relief, haemodynamic improvement, increased survival and end-organ protection. Future research is required to develop innovative pharmacotherapies capable of relieving congestion while simultaneously preventing end-organ damage.

Population-based meta-analysis of hydrochlorothiazide pharmacokinetics

Hydrochlorothiazide (HCTZ) is a thiazide diuretic used for the treatment of hypertension and edema associated with fluid overload conditions such as congestive heart failure (CHF). A population-based meta-analysis approach in NONMEM® was used to develop a PK model to characterize the time-course of HCTZ concentrations in plasma and excretion into the urine for healthy subjects and CHF patients. Data from healthy subjects receiving 100 mg of oral HCTZ were supplemented with additional plasma concentration and urinary excretion versus time data published in the literature following administration of oral HCTZ doses ranging from 10 to 500 mg to healthy subjects or patients with renal failure, CHF or hypertension. A two-compartment model with first-order oral absorption, using a Weibull function, and first-order elimination best described HCTZ PK. Creatinine clearance (CLCR ) was a statistically significant predictor of renal clearance (CLR ). Non-renal clearance was estimated to be 2.44 l/h, CLR was 18.3 l/h and T1/2,α was 1.6 h and T1/2,β was 14.8 h for a typical individual with normal renal function (CLCR  = 120 ml/min). However, CLR was reduced to 10.5, 5.47 and 2.70 l/h in mild (CLCR  = 80 ml/min), moderate (CLCR  = 50 ml/min) and severe (CLCR  = 30 ml/min) renal impairment, respectively. Model diagnostics helped to demonstrate that the population PK model reasonably predicts the rate of urinary HCTZ excretion over time using dosing history and estimated CLCR , allowing for the convenient assessment of PK-PD relationships for HCTZ when given alone or in combination with other agents used to treat fluid overload conditions.

The use of bumetanide for oliguric acute renal failure in preterm infants

OBJECTIVE

To determine the effects of bumetanide in preterm infants with oliguric acute renal failure (OARF).

STUDY DESIGN

Retrospective data review and multivariate analysis of urine output and serum creatinine, blood urea nitrogen, Na, K, Cl, and Ca levels before, during, and after bumetanide therapy in preterm infants with OARF whose conditions did not respond to furosemide therapy.

RESULTS

A total of 35 infants received bumetanide for OARF after an initial trial of furosemide. Their birth weight, gestational age at birth, and postconceptional age at OARF were 811 ± 326 g, 26 ± 2.75 wks, and 29.2 ± 2.7 wks, respectively. Twenty-nine of the 35 infants (83%) responded to bumetanide. Seventeen of the 35 infants subsequently died in the hospital due to multiorgan dysfunction. For the survivors (n = 18) and 11 of 17 of nonsurvivors, urine output increased from 0.6 ± 0.6 mL/kg/hr to 3.0 ± 2.1 mL/kg/hr during bumetanide therapy (p < .0005). Serum creatinine levels increased from 2.13 ± 0.83 mg/dL to 2.3 ± 0.92 mg/dL (p = .04) during bumetanide treatment, whereas blood urea nitrogen levels decreased after bumetanide therapy from 38 ± 19 mg/dL to 31.67 ± 21.6 mg/dL (p = .049). No significant changes were noted in serum sodium, chloride, or calcium concentration.

CONCLUSIONS

Bumetanide therapy significantly increased urine output within 24-48 hrs, but its use was associated with a transient increase in serum creatinine level. Bumetanide can be used in preterm infants to reverse oliguria when therapy with furosemide fails. Prospective, randomized, controlled trials with long-term follow-up in preterm infants are necessary to establish the usefulness of bumetanide for OARF.

Effects of low-dose liquorice alone or in combination with hydrochlorothiazide on the plasma potassium in healthy volunteers

Both liquorice and thiazide diuretics have hypokalaemic effects. In spite of their prevalent use, there are no studies on hypokalaemia caused by the combination of liquorice and thiazides. We recruited 10 healthy volunteers in order to study the effects of 32 g liquorice alone or in combination with 25mg hydrochlorothiazide a day for 2 weeks. The trial had a randomized, open and crossover design. During the liquorice phase, there were no changes in plasma potassium, sodium, creatinine, renin activity, serum aldosterone, blood pressure or heart rate. Weight tended to increase by 0.4 kg (70.2 to 70.6 kg; p=0.056). During the liquorice-hydrochlorothiazide phase, the plasma potassium decreased by 0.32 mmol/l (p=0.0015), plasma renin activity increased by 1.6 microg/l/h (p=0.0064) and the weight decreased by 0.9 kg (70.5 to 69.6 kg, p=0.0065). Twenty per cent of the subjects (2/10) became hypokalaemic during the combined liquorice-hydrochlorothiazide treatment. Furthermore, both subjects developed hypokalaemia within the first week of the combined treatment leading to premature discontinuation. The evaluation of liquorice consumption habits is warranted when initiating thiazide medications to avoid the excessive risk of hypokalaemia associated with the combined use of low-dose liquorice and thiazide diuretics.

Natriuretic and neurohormonal responses to nesiritide, furosemide, and combined nesiritide and furosemide in patients with stable systolic dysfunction

BACKGROUND

In patients with heart failure, few data describe the neurohormonal response to nesiritide and furosemide either alone or in combination. This study systematically compared the effects of nesiritide, furosemide, and their combination on natriuresis/diuresis and plasma aldosterone in patients with chronic stable heart failure who were relatively diuretic resistant.

HYPOTHESIS

Natriuretic, diuretic, and neurohormonal responses to furosemide and nesiritide will differ when these agents are administered alone vs. in combination.

METHODS

Twenty-eight subjects completed a multicenter, open-label, three-arm crossover study. Each subject received the following treatments in random order on alternate days: (1) furosemide, 40 mg intravenous bolus; (2) nesiritide, 2 microg/kg intravenous bolus followed by a 0.01 microg/kg/min infusion for 6 hours; (3) both furosemide and nesiritide, with furosemide given at least 15 minutes after initiation of nesiritide.

RESULTS

Plasma aldosterone increased by 2.2 +/- 1.6 ng/dL after furosemide alone, decreased by 3.9 +/- 1.6 ng/dL after nesiritide alone (P = 0.005 vs furosemide alone and P = 0.56 vs furosemide plus nesiritide), and decreased by 2.8 +/- 1.6 ng/dL after furosemide plus nesiritide (P = 0.02 vs furosemide alone).

CONCLUSIONS

Furosemide alone produced natriuresis/diuresis and a prompt rise in plasma aldosterone values. Nesiritide alone produced no significant natriuresis/diuresis, but decreased plasma aldosterone values. When furosemide was administered on a background of nesiritide infusion, the observed natriuresis/diuresis was similar to that seen with furosemide alone, without the anticipated increase in plasma aldosterone observed with furosemide alone.

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

IMPORTANCE OF THE FIELD

Diuretics are among the most important drugs of our therapeutic armamentarium and have been broadly used for > 50 years, providing important help towards the treatment of several diseases. Although all diuretics act primarily by impairing sodium reabsorption in the renal tubules, they differ in their mechanism and site of action and, therefore, in their specific pharmacological properties and clinical indications. Loop diuretics are mainly used for oedematous disorders (i.e., cardiac failure, nephrotic syndrome) and for blood pressure and volume control in renal disease; thiazides and related agents are among the most prescribed drugs for hypertension treatment; aldosterone-blockers are traditionally used for primary or secondary aldosteronism; and other diuretic classes have more specific indications.

AREAS COVERED IN THIS REVIEW

This article discusses the mechanisms of action, pharmacological effects and clinical indications of the various diuretic classes used in everyday clinical practice, with emphasis on recent knowledge suggesting beneficial effects of certain diuretics on clinical conditions distinct from the traditional indications of these drugs (i.e., heart protection for aldosterone blockers).

WHAT THE READER WILL GAIN

Reader will gain insights into the effective use of diuretic agents for various medical conditions, representing their established or emerging therapeutic indications.

TAKE HOME MESSAGE

Knowledge of the pharmacologic properties and mechanisms of action of diuretic agents is a prerequisite for the successful choice and effective clinical use of these compounds.

Diuretics in clinical practice. Part II: electrolyte and acid-base disorders complicating diuretic therapy

IMPORTANCE OF THE FIELD

As with all potent therapeutic agents, the use of diuretic compounds has been linked with several adverse effects that may reduce quality of life and patient compliance and, in some cases, may be associated with considerable morbidity and mortality. Among the various types of adverse effects, disturbances of electrolyte and acid-base balance are perhaps the most common, and some of them are the aetiological factors of other side effects (i.e., hypokalaemia causing ventricular arrhythmias or glucose intolerance). The mechanism and site of action and, therefore, the pharmacological effects of each diuretic class largely determine the specific electrolyte or acid-base abnormalities that will accompany the use of each diuretic agent.

AREAS COVERED IN THE REVIEW

This article reviews the major electrolyte disturbances (hypokalaemia, hyperkalaemia, hyponatraemia, disorders of magnesium and calcium balance), as well as the acid-base abnormalities complicating the use of the various diuretic agents.

WHAT THE READER WILL GAIN

The reader will gain insights into the pathogenesis of the diuretic-induced electrolyte and acid-base disorders together with considerations for their prevention and treatment.

TAKE HOME MESSAGE

Knowledge of the pharmacologic properties of each diuretic class and appropriate monitoring of patients under diuretic treatment represent the most important strategies to prevent the development of diuretic-related adverse events and their consequences.

Comparison of the effects of diuretics on blood pressure and arterial stiffness in patients with stroke

OBJECTIVES

Indapamide (IND) and bendroflumethiazide (BDZ) are both widely used in patients with stroke. We compared their effects on arterial blood pressure (BP) and arterial stiffness in a group of patients with stroke.

METHODS

In a prospective, randomized, double-blinded study we investigated the effect of 28-day treatment with BDZ (2.5 mg once daily) or IND (2.5 mg once daily) on BP and arterial stiffness in a group of patients with first-ever ischemic stroke.

RESULTS

All data are expressed as mean (SD). In all, 23 patients completed the protocol (age 70.0 +/- 9.55 years). Group I (IND) and group B (BDZ) comprised 13 and 10 patients, respectively. Groups were well matched for demographics and baseline characteristics. Mean arterial pressure reduction from baseline was I = 14.3 +/- 10.3 mm Hg (P < .001) versus B = 9.1 +/- 11.2 mm Hg (P = .03). Augmentation index (AI) was reduced by: I = 4.94 +/- 7.22% (P = .037) versus B = 6.17 +/- 7.85% (P = .035). Time to reflection was increased by I = 3.22 +/- 9.57 milliseconds (P = .268) versus B = 4.71 +/- 5.30 milliseconds (P = .020). There was no significant difference between the two drugs with regard to change in BP or arterial stiffness. Pooled data showed a reduction in mean arterial pressure by 12.1 +/- 10.77 mm Hg (P < .0001) and in AI by 5.5 +/- 7.36% (P = .002), and a small increase in time to reflection by 3.9 +/- 7.79 milliseconds (P = .029). The change in BP explained up to 28% of the change in AI.

CONCLUSION

Both diuretics altered hemodynamic parameters to a similar extent. The results are consistent with a direct effect of diuretic therapy on vascular function. The influence of both diuretics on arterial stiffness was similar.

Pharmacologic approaches for volume excess in acute kidney injury (AKI)

Volume management is an integral component of the care of patients with acute kidney injury (AKI). Considerable controversy exists regarding the use of pharmacological agents for volume management. Although overt fluid overload is often seen in AKI and may prompt attention for the use of diuretics, often these agents are used in the absence of fluid retention. Over the last decade several new agents have become available for volume removal. We reviewed the literature on this topic and addressed four key questions for the appropriate utilization of these agents. These include the drug targets and mechanism of action of available agents; clinical goals and criteria for timing of intervention; adaptation of therapy for specific clinical settings and measures required for monitoring effectiveness and patient safety. This report details our current knowledge in this area, provides evidence-based clinical practice recommendations where appropriate, and formulates a research agenda to address unanswered questions.

Herbal medicines as diuretics: a review of the scientific evidence

There is increasing interest in the health and wellness benefits of herbs and botanicals. This is with good reason as they might offer a natural safeguard against the development of certain conditions and be a putative treatment for some diseases. One such area may be the lowering of blood pressure in those where it is elevated (i.e., hypertension). One class of clinical medicines used to lower blood pressure are known as diuretics and work by increasing the excretion of urine from the body as well as the amount of sodium in urine. There are a growing number of studies purporting diuretic effects with traditional medicines. The aim of this article was to review these studies and identify which extracts promote diuresis (which we assessed on terms of urine excreted and urinary sodium excretion) and also to identify the research needs in this area. We identified a number of species and genuses reporting diuretic effects. Of these, the most promising, at the present time, are the species Foeniculum vulgare, Fraxinus excelsior, Hibiscus sabdariffa, Petroselinum sativum and Spergularia purpurea, and species from the genuses Cucumis (Cucumis melo and Cucumis trigonus), Equisetum (Equisetum bogotense, Equisetum fluviatile, Equisetum giganteum, Equisetum hiemale var. affine and Equisetum myriochaetum), Lepidium (Lepidium latifolium and Lepidium sativum), Phyllanthus (Phyllanthus amarus, Phyllanthus corcovadensis and Phyllanthus sellowianus) and Sambucus (Sambucus mexicana and Sambucus nigra). However, there the number of studies is limited and we recommend that further studies be conducted to confirm reported effects. Such evidence is needed to provide scientific credence to the folklore use of traditional medicines and even be helpful in the development of future medicines, treatments and treatment guidelines.

Novel strategies: challenge loop diuretics and sodium management in heart failure--Part I

This is the first of a 2-part series. This article reviews the relationships among diuretics, neurohormonal activation, renal function, fluid and Na management, the cardiorenal syndrome, and heart failure. Part II will describe novel therapies based on these relationships, focusing particularly on vasopressin antagonists and treatment using hypertonic saline solution with high-dose loop diuretics. Heart failure (HF) is a complex hemodynamic disorder characterized by chronic and progressive pump failure and fluid accumulation. Diuretics are a vital component of symptomatic management, and enhancing diuretic response in the setting of diuretic resistance is therefore pivotal. In HF patients treated with diuretics, compensatory pathophysiologic mechanisms to maintain vascular resistance, such as nonosmotic stimulation of vasopressin secretion and activation of the renin-angiotensin-aldosterone system and sympathetic nervous system, promote renal Na and water reabsorption. Thus, there remains a need to develop novel therapies for HF patients who are refractory to conventional medical treatment. The conflicting results of diuretic treatments in HF and the importance of Na management in the context of the cardiorenal syndrome and neurohormonal activation have suggested novel and counterintuitive strategies, focusing primarily on the use of vasopressin antagonists and hypertonic saline solution with high doses of loop diuretics and neurohormonal interference. The authors review the current evidence for these therapies and suggest hypothetical bases for their efficacy.

Cardiac hypertrophy: mechanisms and therapeutic opportunities

Cardiac hypertrophy and heart failure are major causes of morbidity and mortality in Western societies. Many factors have been implicated in cardiac remodeling, including alterations in gene expression in myocytes, cardiomyocytes apoptosis, cytokines and growth factors that influence cardiac dynamics, and deficits in energy metabolism as well as alterations in cardiac extracellular matrix composition. Many therapeutic means have been shown to prevent or reverse cardiac hypertrophy. New concepts for characterizing the pathophysiology of cardiac hypertrophy have been drawn from various aspects, including medical therapy and gene therapy, or use of stem cells for tissue regeneration. In this review, we focus on various types of cardiac hypertrophy, defining the causes of hypertrophy, describing available animal models of hypertrophy, discussing the mechanisms for development of hypertrophy and its transition to heart failure, and presenting the potential use of novel promising therapeutic strategies derived from new advances in basic scientific research.

Pharmacological treatment of chronic heart failure

Heart failure (HF) is associated with a high morbidity and mortality in the Western World. Our knowledge of the epidemiology, pathophysiology, and therapy has improved dramatically during the last 20 years. Pharmacological treatment, as it stands today, is a combination of preventive and symptomatic strategies. The mainstay life-saving drugs are angiotensin-converting enzyme inhibitors and beta-blockers. Additional benefits are obtained when angiotensin-receptor blockers or aldosterone antagonists are added. Digitalis and/or diuretics are useful for symptom reduction. In addition, combination therapy with hydralazine and isosorbide dinitrate is recommended in African Americans.

Carbonic anhydrase inhibitors ameliorate the symptoms of hypokalaemic periodic paralysis in rats by opening the muscular Ca2+-activated-K+ channels

Carbonic-anhydrase inhibitors are effective in channelopathies possibly by opening the Ca2+-activated-K+ channels. However, the in vivo effects of these drugs in K+-deficient rats, the animal model of familial hypokalaemic periodic paralysis(hypokalaemic-PP), are currently unknown. Measures of insulin-responses, serum electrolytes levels and patch-clamp experiments were therefore performed in K+ -deficient rats treated in vivo with dichlorphenamide (DCP), ethoxzolamide (ETX), hydrochlorthiazide (HCT), methazolamide (MTZ), bendroflumethiazide (BFT) and acetazolamide (ACTZ). Ten days treatments of K+-deficient rats with DCP, BFT, ETX and ACTZ (5.6 mg/kg per day) restored the serum [K+] to control values and prevented the insulin-induced paralysis. In ex vivo experiments, the carbonic-anhydrase inhibitors enhanced the activity of Ca2+-activated-K+ channels with the order of efficacy: ACTZ>BFT>ETX>DCP. In contrast, HCT and MTZ failed to stimulate the Ca2+-activated-K+ channels and to prevent the hypokalaemia and paralysis. At the concentration of 1mg/kg per day, all these drugs failed to ameliorate the hypokalaemic-PP symptoms. The activation of Ca2+-activated-K+ channel in addition to the mild diuretic effect explained the efficacy of ACTZ and DCP in K+ -deficient rats and in familial hypokalaemic-PP.

Clear cell type of renal cell carcinoma with numerous hyaline globules: a diagnostic pitfall

A unique and never-before-published example of clear cell renal cell carcinoma (CRCC) found among 9000 primary renal cell tumors is presented. The tumor contained such a dense concentration of glassy hyaline globules (GHG) in the cytoplasm of the neoplastic cells that it overshadowed the morphology of the neoplasm. The resulting appearance of the tumor was quite misleading and different from the conventional CRCC. The GHG were 7-30 microm in diameter. They were glassy and pale to slightly eosinophilic in color in hematoxylin-eosin. The GHG stained positively with periodic acid-Schiff and negatively with silver and Hale's colloidal iron. Immunohistochemically, they were also negative for anti Mycobacterium bovis antigen. At the ultrastructural level, the GHG were formed by an amorphous mass of stellate shape. The GHG were localized within rough endoplasmic reticulum. Molecular genetically, mutation of the distal part of exon 3 of the VHL gene causing elongation of the VHL protein was found in the tumor, thus confirming the diagnosis of CRCC.

Use of diuretics in cardiovascular diseases: (1) heart failure

Diuretics are used extensively in hospitals and in community medical practice for the management of cardiovascular diseases. They are used frequently as the first line treatment for mild to moderate hypertension and are an integral part of the management of symptomatic heart failure. Although diuretics have been used for several decades, there is still some ambiguity and confusion regarding the optimal way of using these common drugs. In this paper, the classes and action of diuretics are reviewed, and the various indications, optimal doses, and recommendations on the effective use of these agents are discussed.

Use of diuretics in cardiovascular disease: (2) hypertension

Hypertension is a common condition associated with increased mortality and multiple morbidities. Evidence based management of hypertension is known to improve both the short term and the long term outcomes in patients with this condition. There are several general measures and pharmacological agents that are known to treat hypertension adequately. Diuretics, in particular low dose thiazide and thiazide-like diuretics, are widely used in the treatment of hypertension. They have excellent outcome data and high safety and low side effects profiles. In this article, the physiology, pharmacological actions, side effects, and outcome data of the use of diuretics in hypertension are reviewed. In addition, the effective use of diuretics in the management of hypertension is discussed.

THEINTEGRATION OFPHARMACOKINETICS ANDPHARMACODYNAMICS: Understanding Dose-Response

Pharmacokinetic (PK) and pharmacodynamic (PD) studies have proven to be powerful and instructive tools, particularly in elucidating important aspects of human pharmacology. Nevertheless, they remain imperfect tools in that they only allow researchers to indirectly extrapolate, through computational modeling, the dynamic processes of drug action. Furthermore, neither tool alone provides a complete nor necessarily relevant picture of drug action. This review explores the utility and applications of PK and PD in the study of drugs, provides examples of lessons learned from their application to studies of human pharmacology, points out some of their limitations, and advances the thesis that these tools ideally should be employed together in an integrated approach. As we continue to apply these tools across the continuum of age and disease, they provide a powerful means to enhance our understanding of drug action, drug interactions, and intrinsic host factors that influence pharmacologic response.

Effect of thiazide drug compound on the testicular protein and cholesterol contents of albino rat

In this study the effect of thiazide diuretic compound on the protein and cholesterol contents in the testes of albino rats as the experimental model. The drug thiazide was administered orally daily for 10,20 and 30 days at the dose of 100mg/kg body weight. Total protein decrease in the testes of rats were evidenced may be due to the side effects of thiazide drug compound which is linked with the hyponatremia and protein metabolism. An elevated level of cholesterol contents observed in thiazide treated rats also revealed that the side effect of drug compound thiazide and also may be due to the stimulation of catecholamine which is stimulated therefore, the biochemical estimation such as protein and cholesterol in the testes after the thiazide treatment determined the effectiveness of diuretic drug compound would provide clinical evidences of their side effects.

Pharmacologic therapy for patients with chronic heart failure and reduced systolic function: review of trials and practical considerations

Heart failure (HF) is a complex clinical syndrome resulting from any structural or functional cardiac disorder impairing the ability of the ventricles to fill with or eject blood. The approach to pharmacologic treatment has become a combined preventive and symptomatic management strategy. Ideally, treatment should be initiated in patients at risk, preventing disease progression. In patients who have progressed to symptomatic left ventricular dysfunction, certain therapies have been demonstrated to improve survival, decrease hospitalizations, and reduce symptoms. The mainstay therapies are angiotensin-converting enzyme (ACE) inhibitors and beta-blockers (bisoprolol, carvedilol, and metoprolol XL/CR), with diuretics to control fluid balance. In patients who cannot tolerate ACE inhibitors because of angioedema or severe cough, valsartan can be substituted. Valsartan should not be added in patients already taking an ACE inhibitor and a beta-blocker. Spironolactone is recommended in patients who have New York Heart Association (NYHA) class III to IV symptoms despite maximal therapies with ACE inhibitors, beta-blockers, diuretics, and digoxin. Low-dose digoxin, yielding a serum concentration <1 ng/mL can be added to improve symptoms and, possibly, mortality. The combination of hydralazine and isosorbide dinitrate might be useful in patients (especially in African Americans) who cannot tolerate ACE inhibitors or valsartan because of hypotension or renal dysfunction. Calcium antagonists, with the exception of amlodipine, oral or intravenous inotropes, and vasodilators, should be avoided in HF with reduced systolic function. Amiodarone should be used only if patients have a history of sudden death, or a history of ventricular fibrillation or sustained ventricular tachycardia, and should be used in conjunction with an implantable defibrillator [corrected]. Finally, anticoagulation is recommended only in patients who have concomitant atrial fibrillation or a previous history of cerebral or systemic emboli.

Clinical pharmacology of antihypertensive drugs

Systemic hypertension is a major public health problem and is perhaps the most common chronic disorder in most societies. Most patients with vascular disease report hypertension in their medical history. Irrespective of the specialty that one practices, every physician will likely encounter patients with systemic hypertension. Unfortunately, an overwhelming number have so-called "primary" or "essential" hypertension for which a cure has yet to be found. Fortunately, excellent therapy is available to control this modern malady. The field of hypertension continues to evolve rapidly, particularly in the field of therapy. During the past two decades, the treatment of hypertension has moved from a cookbook approach to more scientifically based individualized management. This paradigm shift requires the practitioner to acquire sufficient knowledge about individual drugs and how they work in a given patient. Rapid expansion of available drugs has placed a burden on the clinician to keep up with these advances. We hope that the discussions contained herein will ease that burden somewhat and make the treatment options less cumbersome. This article addresses the practical issues related to selection of antihypertensive drugs and provides an overview of advantages and disadvantages of individual drug classes. The reader should also refer to the JNC VI document [1] to further understand the selection of drug therapy based upon compelling indications. The ultimate aim of hypertension management should always be to achieve target or goal blood pressure levels.

Spironolactone abolishes the relationship between aldosterone and plasminogen activator inhibitor-1 in humans

Recent studies have defined a link between the renin-angiotensin-aldosterone system and fibrinolysis. The present study tests the hypothesis that endogenous aldosterone regulates plasminogen activator inhibitor-1 (PAI-1) production in humans. Hemodynamic parameters, PAI-1 and tissue-type plasminogen activator (t-PA) antigen, potassium, PRA, angiotensin II, and aldosterone were measured in nine male hypertensive subjects after a 3-wk washout, after 2 wk of hydrochlorothiazide (HCTZ; 25 mg plus 20 mmol KCl/d), and after 2 wk of spironolactone (100 mg/d plus KCl placebo). Spironolactone (P = 0.04), but not HCTZ (P = 0.57 vs. baseline; P = 0.1 vs. spironolactone), significantly lowered systolic blood pressure. Angiotensin II increased from baseline during both HCTZ (P = 0.02) and spironolactone (P = 0.02 vs. baseline; P = 0.19 vs. HCTZ) treatments. Although both HCTZ (P = 0.004) and spironolactone (P < 0.001 vs. baseline) increased aldosterone, the effect was greater with spironolactone (P < 0.001 vs. HCTZ). HCTZ increased PAI-1 antigen (P = 0.02), but did not alter t-PA antigen. In contrast, there was no effect of spironolactone on PAI-1 antigen (P = 0.28), whereas t-PA antigen was increased (P = 0.01). There was a significant correlation between PAI-1 antigen and serum aldosterone during both baseline and HCTZ study days (r(2) = 0.57; P = 0.0003); however, treatment with spironolactone abolished this correlation (r(2) = 0.13; P = 0.33). This study provides evidence that endogenous aldosterone influences PAI-1 production in humans.

Drug discovery and the intracellular receptor family

Drug discovery using intracellular receptors (IRs) as targets presents its own set of unique complications and advantages. The natural ligands for these receptors are, in many cases, already used as drugs. To effectively exploit these targets, newer molecules must have either increased receptor selectivity or increased tissue or gene selectivity to reduce side effects. The search for these molecules will yield new therapeutics as well as new insights into the mechanism of action of these receptors and their ligands.