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Cichelero FT, Fuchs SC, Jorge JA, Martinez D, Oliveira GPF, Lucca MB, Oliveira ACT, Fuchs FD. Effect of antihypertensive agents on sleep apnea and ambulatory blood pressure in patients with hypertension: A randomized controlled trial. Sleep Med 2024; 119:417-423. [PMID: 38781664 DOI: 10.1016/j.sleep.2024.05.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 05/09/2024] [Accepted: 05/16/2024] [Indexed: 05/25/2024]
Abstract
BACKGROUND Obstructive sleep apnea (OSA) and hypertension are common conditions that may be linked through sympathetic activation and water retention. We hypothesized that diuretics, which reduce the body water content, may be more effective than amlodipine, a blood pressure (BP)-lowering agent implicated with edema, in controlling OSA in patients with hypertension. We also aimed to compare the effects of these treatments on ambulatory blood pressure monitoring (ABPM). METHODS In a randomized, double-blind clinical trial, we compared the effects of chlorthalidone/amiloride 25/5 mg with amlodipine 10 mg on OSA measured by portable sleep monitor and BP measured by ABPM. The study included participants older than 40 who had moderate OSA (10-40 apneas/hour of sleep) and BP within the systolic range of 140-159 mmHg or diastolic range of 90-99 mmHg. RESULTS The individuals in the experimental groups were comparable in age, gender, and other relevant characteristics. Neither the combination of diuretics nor amlodipine alone reduced the AHI after 8 weeks of treatment (AHI 26.3 with diuretics and 25.0 with amlodipine. P = 0.713). Both treatments significantly lowered office, 24-h, and nighttime ABP, but the two groups had no significant difference. CONCLUSION Chlorthalidone associated with amiloride and amlodipine are ineffective in decreasing the frequency of sleep apnea episodes in patients with moderate OSA and hypertension. Both treatments have comparable effects in lowering both office and ambulatory blood pressure. The notion that treatments could offer benefits for both OSA and hypertension remains to be demonstrated. TRIAL REGISTRATION CLINICALTRIALS. GOV IDENTIFIER NCT01896661.
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Shinohara Y, Komiya Y, Morimoto K, Endo Y, Terashima M, Suzuki T, Takino T, Ninomiya I, Yamada H, Uto Y. Development of UTX-143, a selective sodium-hydrogen exchange subtype 5 inhibitor, using amiloride as a lead compound. Bioorg Med Chem 2024; 99:117603. [PMID: 38246115 DOI: 10.1016/j.bmc.2024.117603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 01/06/2024] [Accepted: 01/11/2024] [Indexed: 01/23/2024]
Abstract
NHE5, an isoform of the Na+/H+ exchanger (NHE) protein, is an ion-transporting membrane protein that regulates intracellular pH and is highly expressed in colorectal adenocarcinoma. Therefore, we hypothesized that NHE5 inhibitors can be used as anticancer drugs. However, because NHE1 is ubiquitously expressed in all cells, it is extremely important to demonstrate its selective inhibitory activity against NHE5. We used amiloride, an NHE non-selective inhibitor, as a lead compound and created UTX-143, which has NHE5-selective inhibitory activity, using a structure-activity relationship approach. UTX-143 showed selective cytotoxic effects on cancer cells and reduced the migratory and invasive abilities of cancer cells. These results suggest a new concept wherein drugs exhibit cancer-specific cytotoxic effects through selective inhibition of NHE5 and the possibility of UTX-143 as a lead NHE5-selective inhibitor.
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Gei L, Yan Y, Xing W, Li Q, Chen X, Yan F, Wang Y, Cao Y, Jiang W, E R, Luo D, Zhang Y, Zeng W, Chen D. Amiloride alleviates morphine tolerance by suppressing ASIC3-dependent neuroinflammation in the spinal cord. Eur J Pharmacol 2024; 963:176173. [PMID: 37918499 DOI: 10.1016/j.ejphar.2023.176173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 10/30/2023] [Accepted: 10/30/2023] [Indexed: 11/04/2023]
Abstract
BACKGROUND The use of morphine in clinical medicine is severely constrained by tolerance. Therefore, it is essential to examine pharmacological therapies that suppress the development of morphine tolerance. Amiloride suppressed the expression of inflammatory cytokines by inhibiting microglial activation. Microglia play a crucial role in the establishment of morphine tolerance. Thus, we anticipated that amiloride might suppress the development of morphine tolerance. During this investigation, we assessed the impact of amiloride on mouse morphine tolerance. METHODS Mice received morphine (10 mg/kg, s.c.) twice daily with intrathecally injected amiloride (0.3 μg/5 μl, 1 μg/5 μl, and 3 μg/5 μl) for nine continuous days. To assess morphine tolerance, mice underwent the tail-flick and hot plate tests. BV-2 cells were used to investigate the mechanism of amiloride. By using Western blotting, real-time PCR, and immunofluorescence labeling methods, the levels of acid-sensing ion channels (ASICs), nuclear factor kappa B (NF-kB) p65, p38 mitogen-activated protein kinase (MAPK) proteins, and neuroinflammation-related cytokines were determined. RESULTS The levels of ASIC3 in the spinal cord were considerably increased after long-term morphine administration. Amiloride was found to delay the development of tolerance to chronic morphine assessed via tail-flick and hot plate tests. Amiloride reduced microglial activation and downregulated the cytokines IL-1β and TNF-a by inhibiting ASIC3 in response to morphine. Furthermore, amiloride reduced p38 MAPK phosphorylation and inhibited NF-κB expression. CONCLUSIONS Amiloride effectively reduces chronic morphine tolerance by suppressing microglial activation caused by morphine by inhibiting ASIC3.
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Hrvat A, Schmidt M, Wagner B, Zwanziger D, Kimmig R, Volbracht L, Brandau S, Mallmann-Gottschalk N. Electrolyte imbalance causes suppression of NK and T cell effector function in malignant ascites. J Exp Clin Cancer Res 2023; 42:235. [PMID: 37684704 PMCID: PMC10485936 DOI: 10.1186/s13046-023-02798-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 08/13/2023] [Indexed: 09/10/2023] Open
Abstract
BACKGROUND Malignant ascites commonly occurs in advanced or recurrent stages of epithelial ovarian cancer during peritoneal carcinomatosis and is correlated with poor prognosis. Due to its complex composition of cellular and acellular components malignant ascites creates a unique tumor microenvironment, which mediates immunosuppression and promotes progression of disease. However, the immunosuppressive mechanisms remain poorly understood. METHODS In the present study, we explored the antitumor activity of healthy donor NK and T cells directed against ovarian cancer cells in presence of malignant ascites derived from patients with advanced or recurrent peritoneal carcinomatosis. A wide range of methods was used to study the effect of ascites on NK and T cells (FACS, ELISA, EliSpot, qPCR, Live-cell and confocal microscopy, Western blot and electrolyte flux assays). The ascites components were assessed using quantitative analysis (nephelometry, potentiometry and clinical chemistry) and separation methods (dialysis, ultracentrifugal filtration and lipid depletion). RESULTS Ascites rapidly inhibited NK cell degranulation, tumor lysis, cytokine secretion and calcium signaling. Similarly, target independent NK and T cell activation was impaired in ascites environment. We identified imbalanced electrolytes in ascites as crucial factors causing extensive immunosuppression of NK and T cells. Specifically, high sodium, low chloride and low potassium content significantly suppressed NK-mediated cytotoxicity. Electrolyte imbalance led to changes in transcription and protein expression of electrolyte channels and impaired NK and T cell activation. Selected inhibitors of sodium electrolyte channels restored intracellular calcium flux, conjugation, degranulation and transcript expression of signaling molecules. The levels of ascites-mediated immunosuppression and sodium/chloride/potassium imbalance correlated with poor patient outcome and selected molecular alterations were confirmed in immune cells from ovarian cancer patients. CONCLUSION Our data suggest a novel electrolyte-based mechanism of immunosuppression in malignant ascites of patients with peritoneal carcinomatosis. We show for the first time that the immunosuppression of NK cytotoxicity in coculture assays is correlated to patient poor survival. Therapeutic application of sodium channel inhibitors may provide new means for restoring immune cell activity in ascites or similar electrolyte imbalanced environments.
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Zhang L, Wang X, Chen J, Sheng S, Kleyman TR. Extracellular intersubunit interactions modulate epithelial Na + channel gating. J Biol Chem 2023; 299:102914. [PMID: 36649907 PMCID: PMC9975279 DOI: 10.1016/j.jbc.2023.102914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 12/13/2022] [Accepted: 01/12/2023] [Indexed: 01/15/2023] Open
Abstract
Epithelial Na+ channels (ENaCs) and related channels have large extracellular domains where specific factors interact and induce conformational changes, leading to altered channel activity. However, extracellular structural transitions associated with changes in ENaC activity are not well defined. Using crosslinking and two-electrode voltage clamp in Xenopus oocytes, we identified several pairs of functional intersubunit contacts where mouse ENaC activity was modulated by inducing or breaking a disulfide bond between introduced Cys residues. Specifically, crosslinking E499C in the β-subunit palm domain and N510C in the α-subunit palm domain activated ENaC, whereas crosslinking βE499C with αQ441C in the α-subunit thumb domain inhibited ENaC. We determined that bridging βE499C to αN510C or αQ441C altered the Na+ self-inhibition response via distinct mechanisms. Similar to bridging βE499C and αQ441C, we found that crosslinking palm domain αE557C with thumb domain γQ398C strongly inhibited ENaC activity. In conclusion, we propose that certain residues at specific subunit interfaces form microswitches that convey a conformational wave during ENaC gating and its regulation.
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Zhao J, Wu F, He Q, Feng Y. Enhanced degradation of amiloride over Bi 2FeNbO 7/bisulfite process: Key factors and mechanism. CHEMOSPHERE 2022; 300:134573. [PMID: 35436455 DOI: 10.1016/j.chemosphere.2022.134573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/13/2022] [Accepted: 04/07/2022] [Indexed: 06/14/2023]
Abstract
Construction of Bi2FeNbO7/bisulfite system for abatement of pharmaceutical residue was achieved. An attempt to synthesize Bi2FeNbO7 through hydrothermal technique was confirmed by X-ray diffraction. The magnetic field experiment revealed that Bi2FeNbO7 possessed a saturation magnetization of 6.99 emu/g, indicating magnetic attributes of Bi2FeNbO7. Scanning electron microscopy images showed that Bi2FeNbO7 exhibited regular octahedra in the size of 200-300 nm. In a self-made device, the activation of sodium bisulfite using Bi2FeNbO7 for the disposal of amiloride has been carefully explored. The effects of solution pH, sodium bisulfite concentration, Bi2FeNbO7 dosage, amiloride concentration, coexisting ions, and water matrix on the performance of Bi2FeNbO7/bisulfite system was investigated. The catalytic performance of Bi2FeNbO7/bisulfite to degrade amiloride was considerably higher than that of traditional iron oxides. The maximum removal efficiency of amiloride was 97.9% in Bi2FeNbO7/bisulfite process. The involvement of Fe might be crucial for activating bisulfite to create active species. The dominating radical in Bi2FeNbO7/bisulfite process was identified as SO3•‒. With the help of UHPLC/MS/MS, three new degradation products of amiloride were found. Dehalogenation and deamination of amiloride might account for the formation of these transformation products. This work provides a highly efficient Bi2FeNbO7/bisulfite process for the disposal of pharmaceutical pollutants in water treatment.
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Chaudhary S, Kumar P, Kaushik M. Exploring the interaction of guanidine ligands Amiloride, Rimeporide and Cariporide with DNA for understanding their role as inhibitors of Na +/H + exchangers (NHEs): A spectroscopic and molecular docking investigation. Int J Biol Macromol 2022; 213:834-844. [PMID: 35675859 DOI: 10.1016/j.ijbiomac.2022.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/26/2022] [Accepted: 06/02/2022] [Indexed: 11/05/2022]
Abstract
The inhibition of Na+/H+ Exchangers (NHEs) has shown efficacy in the pathology of several diseases like tumors, cardiovascular, and neurological disorders. The role of guanidine ligands such as amiloride, cariporide, and rimeporide as NHE inhibitors is very well documented but their interaction studies with genomic DNA are still unexplored. In this study, a combination of various biophysical and molecular docking studies was employed to investigate their binding aspects.UV-Visible, fluorescence, and circular dichroism (CD) studies indicated that guanidine ligands bind to the grooves of Calf Thymus DNA (ctDNA). Fluorescence titration studies depict that amiloride binds to ctDNA with a binding constant in the order of 102 M-1 and free energy change (ΔG0) of -14.05 KJ mol-1. Competitive fluorescence studies indicated the minor groove binding property of amiloride, whereas major groove binding mode was deduced for rimeporide and cariporide. Molecular docking studies were also found to be in accordance with the experimental results, revealing the information about the binding energy of the guanidine ligand-ctDNA complex. The docked structures depicted binding energy of -6.4 kcal mol-1 for amiloride and - 6.6 kcal mol-1 for rimeporide and cariporide. Such physicochemical studies of DNA-ligand interactions may facilitate the understanding of the mechanisms of NHE inhibition.
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Amiloride is a suitable fluorescent substrate for the study of the drug transporter human multidrug and toxin extrusion 1 (MATE1). Biochem Biophys Res Commun 2022; 592:113-118. [PMID: 35042121 DOI: 10.1016/j.bbrc.2022.01.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 01/06/2022] [Indexed: 11/24/2022]
Abstract
Human multidrug and toxin extrusion 1 (MATE1; SLC47A1) is highly expressed in the kidneys and the liver. It plays a significant role in drug and endogenous compound disposition, and therefore, a rapid evaluation of its inhibition is important for drug development and for the understanding of renal and hepatic physiology. Amiloride is a potassium-sparing diuretic used for treating hypertension; it also demonstrates strong fluorescence in organic solvent or detergent solutions. In this study, we investigated the transport characteristics of amiloride by human MATE1. Cellular accumulation of amiloride was evaluated in control vector- or MATE1-transfected HEK293 cells. Cells were lysed with 1% sodium dodecyl sulfate, and fluorescence was measured using a microplate reader at wavelengths of 364ex and 409em. With ammonium prepulse-induced intracellular acidification, MATE1 transported amiloride at an extracellular pH of 7.4. The uptake demonstrated an overshoot phenomenon and saturated, with the Km and Vmax being 23.5 μM and 1.01 nmol/mg/min, respectively. MATE1-mediated amiloride transport also presented with a bell-shaped pH profile that reached a maximum pH value of 7.4. The inhibitor sensitivity of MATE1-facilitated amiloride transport was similar to those of known substrates, such as tetraethylammonium and metformin. Among the tested inhibitors, pyrimethamine demonstrated the most potent inhibition with an IC50 value of 0.266 μM. Furthermore, MATE1 was found to be inhibited by fampridine, which was previously considered to be a non-inhibitor of MATE1. This study demonstrates that amiloride is a suitable fluorescent substrate for the in vitro study of the transport activity of MATE1.
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Adedara IA, Costa FV, Biasuz E, Canzian J, Farombi EO, Rosemberg DB. Influence of acid-sensing ion channel blocker on behavioral responses in a zebrafish model of acute visceral pain. Behav Brain Res 2022; 416:113565. [PMID: 34499933 DOI: 10.1016/j.bbr.2021.113565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/03/2021] [Accepted: 08/25/2021] [Indexed: 11/25/2022]
Abstract
Acid-sensing ion channels (ASICs) play significant roles in numerous neurological and pathological conditions, including pain. Although acid-induced nociception has been characterized previously in zebrafish, the contribution of ASICs in modulating pain-like behaviors is still unknown. Here, we investigated the role of amiloride, a nonselective ASICs blocker, in the negative modulation of specific behavioral responses in a zebrafish-based model of acute visceral pain. We verified that intraperitoneal injection (i.p.) of 0.25, 0.5, 1.0, and 2.0 mg/mL amiloride alone or vehicle did not change zebrafish behavior compared to saline-treated fish. Administration of 2.5% acetic acid (i.p.) elicited writhing-like response evidenced by the abnormal body curvature and impaired locomotion and motor activity. Attenuation of acetic acid-induced pain was verified at lower amiloride doses (0.25 and 0.5 mg/mL) whereas 1.0 and 2.0 mg/mL abolished pain-like responses. The protective effect of the highest amiloride dose tested was evident in preventing writhing-like responses and impaired locomotion and vertical activity. Collectively, amiloride antagonized abdominal writhing-like phenotype and aberrant behaviors, supporting the involvement of ASICs in a zebrafish-based model of acute visceral pain.
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Abbasloo E, Abdollahi F, Saberi A, Esmaeili-Mahani S, Kaeidi A, Akhlaghinasab F, Sheibani V, Thomas TC, Kobeissy FH, Oryan S. Involvement of T-type calcium channels in the mechanism of low dose morphine-induced hyperalgesia in adult male rats. Neuropeptides 2021; 90:102185. [PMID: 34419803 DOI: 10.1016/j.npep.2021.102185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 07/19/2021] [Accepted: 08/09/2021] [Indexed: 11/23/2022]
Abstract
It has been shown that systemic and local administration of ultra-low dose morphine induced a hyperalgesic response via mu-opioid receptors. However, its exact mechanism(s) has not fully been clarified. It is documented that mu-opioid receptors functionally couple to T-type voltage dependent Ca+2 channels. Here, we investigated the role of T-type calcium channels, amiloride and mibefradil, on the induction of low-dose morphine hyperalgesia in male Wistar rats. The data showed that morphine (0.01 μg i.t. and 1 μg/kg i.p.) could elicit hyperalgesia as assessed by the tail-flick test. Administration of amiloride (5 and 10 μg i.t.) and mibefradil (2.5 and 5 μg i.t.) completely blocked low-dose morphine-induced hyperalgesia in spinal dorsal horn. Amiloride at doses of 1 and 5 mg/kg (i.p.) and mibefradil (9 mg/kg ip) 10 min before morphine (1 μg/kg i.p.) inhibited morphine-induced hyperalgesia. Our results indicate a role for T-type calcium channels in low dose morphine-induced hyperalgesia in rats.
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Ali AE, Elsherbiny DM, Azab SS, El-Demerdash E. The diuretic amiloride attenuates doxorubicin-induced chemobrain in rats: Behavioral and mechanistic study. Neurotoxicology 2021; 88:1-13. [PMID: 34656704 DOI: 10.1016/j.neuro.2021.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 10/08/2021] [Accepted: 10/12/2021] [Indexed: 11/26/2022]
Abstract
Cognitive impairment or "chemobrain" is a troublesome adverse effect which had been increasingly reported by cancer patients after doxorubicin (DOX) chemotherapy. Notably, Hypertension, a very common comorbidity in cancer patients, could pose a greater risk for negative cognitive outcomes. Amiloride (AML) is an antihypertensive, potassium-sparing diuretic that has been proven to be neuroprotective in different experimental models; this can be attributed to its ability to inhibit different ion transporters such as Na+/H+ exchanger (NHE), which upon excessive activation can result in intracellular cationic overload, followed by oxidative damage and cellular death. Accordingly, this study was designed to investigate the potential neuroprotective effect of AML against DOX-induced chemobrain and to elucidate possible underlying mechanisms. Briefly, Histopathological examination and neurobehavioral testing (Morris water maze, Y maze and passive avoidance test) showed that AML co-treatment (10 mg/kg/day) markedly attenuated DOX (2 mg/kg/week)-induced neurodegeneration and memory impairment after 4 weeks of treatments. We found that DOX administration up-regulated NHE expression and increased lactic acid content in the hippocampus which were markedly opposed by AML. Moreover, AML mitigated DOX-induced neuroinflammation and decreased hippocampal tumor necrosis factor-α level, nuclear factor kappa-B, and cyclooxygenase-2 expression. Additionally, AML counteracted DOX-induced hippocampal oxidative stress as indicated by normalized malondialdehyde and glutathione levels. Furthermore, AML halted DOX-induced hippocampal apoptosis as evidenced by decreased caspase-3 activity and lower cytochrome c immunoexpression. Our results in addition to the previously reported antitumor effects of AML and its ability to mitigate cancer resistance to DOX therapy could point toward possible new repositioning scenarios of the diuretic AML especially regarding hypertensive cancer patients.
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Hemdan AM. Mathematical Modeling for HPLC Separation and Quantification of an Anti-Hypertensive Combination by Response Surface Methodology. J AOAC Int 2021; 105:623-629. [PMID: 34519824 DOI: 10.1093/jaoacint/qsab123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 08/31/2021] [Indexed: 11/14/2022]
Abstract
BACKGROUND Determination of a multi-component mixture by HPLC requires many preliminary runs for method development which is both time-consuming and expensive due to the usage of large solvent volumes. OBJECTIVE In the present study, the main objective was to reduce the preliminary runs that are required for optimizing the method conditions and also shorten the run time of analysis to be suitable for quality control laboratories where there is a large number of samples to be analyzed. METHODS That was achieved using Two-factor three-level Response surface experiment which is a multivariate design that predicts the significant factors for optimizing the studied responses. RESULTS The response surface design suggests that both acetonitrile ratio and flow rate are significant factors for full resolution of the studied mixture; atenolol, amiloride, and hydrochlorothiazide. The studied mixture was fully separated and determined in less than 5 min with perfect resolution. CONCLUSION Experimental design is a very beneficial tool for optimization of the method conditions in HPLC, especially if the studied mixture ingredients have overlapping peaks. For atenolol, amiloride, and hydrochlorothiazide, acetonitrile and flow rate were found to be the significant factors that affect the resolution of the studied mixture. HIGHLIGHTS Response surface design is a powerful tool that could be used for predicting the significant factors for separation in HPLC. Optimization of the method conditions was done using a limited number of preliminary runs. The studied ternary mixture was fully separated in less than five minutes with the aid of experimental design.
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Abstract
Amiloride is a potassium retaining diuretic and natriuretic which acts by reversibly
blocking luminal epithelial sodium channels (ENaCs) in the late distal tubule and
collecting duct. Amiloride is indicated in oedematous states, and for potassium
conservation adjunctive to thiazide or loop diuretics for hypertension, congestive heart
failure and hepatic cirrhosis with ascites. Historical studies on its use in hypertension
were poorly controlled and there is insufficient data on dose-response. It is clearly
highly effective in combination with thiazide diuretics where it counteracts the adverse
metabolic effects of the thiazides and its use in the Medical Research Council Trial of
Older Hypertensive Patients, demonstrated convincing outcome benefits on stroke and
coronary events. Recently it has been shown to be as effective as spironolactone in
resistant hypertension but there is a real need to establish its potential role in the
much larger number of patients with mild to moderate hypertension in whom there is a
paucity of information with amiloride particularly across an extended dose range.
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Zhou L, Zhang T, Shao W, Lu R, Wang L, Liu H, Jiang B, Li S, Zhuo H, Wang S, Li Q, Huang C, Lin D. Amiloride ameliorates muscle wasting in cancer cachexia through inhibiting tumor-derived exosome release. Skelet Muscle 2021; 11:17. [PMID: 34229732 PMCID: PMC8258996 DOI: 10.1186/s13395-021-00274-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 06/23/2021] [Indexed: 12/25/2022] Open
Abstract
Background Cancer cachexia (CAC) reduces patient survival and quality of life. Developments of efficient therapeutic strategies are required for the CAC treatments. This long-term process could be shortened by the drug-repositioning approach which exploits old drugs approved for non-cachexia disease. Amiloride, a diuretic drug, is clinically used for treatments of hypertension and edema due to heart failure. Here, we explored the effects of the amiloride treatment for ameliorating muscle wasting in murine models of cancer cachexia. Methods The CT26 and LLC tumor cells were subcutaneously injected into mice to induce colon cancer cachexia and lung cancer cachexia, respectively. Amiloride was intraperitoneally injected daily once tumors were formed. Cachexia features of the CT26 model and the LLC model were separately characterized by phenotypic, histopathologic and biochemical analyses. Plasma exosomes and muscle atrophy-related proteins were quantitatively analyzed. Integrative NMR-based metabolomic and transcriptomic analyses were conducted to identify significantly altered metabolic pathways and distinctly changed metabolism-related biological processes in gastrocnemius. Results The CT26 and LLC cachexia models displayed prominent cachexia features including decreases in body weight, skeletal muscle, adipose tissue, and muscle strength. The amiloride treatment in tumor-bearing mice distinctly alleviated muscle atrophy and relieved cachexia-related features without affecting tumor growth. Both the CT26 and LLC cachexia mice showed increased plasma exosome densities which were largely derived from tumors. Significantly, the amiloride treatment inhibited tumor-derived exosome release, which did not obviously affect exosome secretion from non-neoplastic tissues or induce observable systemic toxicities in normal healthy mice. Integrative-omics revealed significant metabolic impairments in cachectic gastrocnemius, including promoted muscular catabolism, inhibited muscular protein synthesis, blocked glycolysis, and impeded ketone body oxidation. The amiloride treatment evidently improved the metabolic impairments in cachectic gastrocnemius. Conclusions Amiloride ameliorates cachectic muscle wasting and alleviates cancer cachexia progression through inhibiting tumor-derived exosome release. Our results are beneficial to understanding the underlying molecular mechanisms, shedding light on the potentials of amiloride in cachexia therapy. Supplementary Information The online version contains supplementary material available at 10.1186/s13395-021-00274-5.
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Shen W, Alshehri M, Desale S, Wilcox C. The Effect of Amiloride on Proteinuria in Patients with Proteinuric Kidney Disease. Am J Nephrol 2021; 52:368-377. [PMID: 33957621 DOI: 10.1159/000515809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 03/05/2021] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Proteinuric kidney diseases share an aggressive clinical course of developing end-stage renal disease. However, the treatment is limited. Amiloride, an epithelial sodium channel (ENaC) inhibitor, was reported to reduce proteinuria in animal studies and case reports independent of ENaC inhibition. We hypothesized that amiloride not triamterene (an analog of amiloride) would reduce proteinuria in the patients with proteinuric kidney disease. METHODS Patients with proteinuria >1.0 g/day and estimated glomerular filtration rate (eGFR) >30 mL/min/1.73 m2 on a maximum tolerable dose of angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers were randomized to receive amiloride 5 mg twice daily or triamterene 50 mg twice daily for 8 weeks, followed by 4 weeks of washout, and then crossed over to the other drug for 8 weeks. The primary outcome was 24-h urine protein reduction. Secondary outcomes were changes in body weight, blood pressure (BP), serum potassium, and eGFR. Data were analyzed by analysis of variance. RESULTS A total of 12 patients completed the study. Amiloride reduced 24-h urine protein by 38.7% (p = 0.002) and decreased systolic BP by 12.3 mm Hg (p = 0.04). Interestingly, triamterene reduced 24 h urine protein as well, by 32.8% (p = 0.02). Triamterene lowered eGFR by 9.0 mL/min/1.73 m2 (p = 0.007), but it was reversible. The average weight change was insignificant in both groups (p = 0.40 and 0.34 respectively). Three patients withdrew the study due to hyperkalemia. CONCLUSIONS Both amiloride and triamterene significantly reduced proteinuria in patients with proteinuric kidney disease. The anti-proteinuric effect was additive to renin-angiotensin-aldosterone system (RAAS) blockade, given all patients were on RAAS blockade. Hyperkalemia was a safety concern. Larger trials might be needed to examine the antiproteinuric effects of ENaC inhibitors.
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Buckley BJ, Aboelela A, Majed H, Bujaroski RS, White KL, Powell AK, Wang W, Katneni K, Saunders J, Shackleford DM, Charman SA, Cook GM, Kelso MJ, Ranson M. Systematic evaluation of structure-property relationships and pharmacokinetics in 6-(hetero)aryl-substituted matched pair analogs of amiloride and 5-(N,N-hexamethylene)amiloride. Bioorg Med Chem 2021; 37:116116. [PMID: 33799173 DOI: 10.1016/j.bmc.2021.116116] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 03/10/2021] [Accepted: 03/12/2021] [Indexed: 10/21/2022]
Abstract
The K+-sparing diuretic amiloride elicits anticancer activities in multiple animal models. During our recent medicinal chemistry campaign aiming to identify amiloride analogs with improved properties for potential use in cancer, we discovered novel 6-(hetero)aryl-substituted amiloride and 5-(N,N-hexamethylene)amiloride (HMA) analogs with up to 100-fold higher potencies than the parent compounds against urokinase plasminogen activator (uPA), one of amiloride's putative anticancer targets, and no diuretic or antikaliuretic effects. Here, we report the systematic evaluation of structure-property relationships (lipophilicity, aqueous solubility and in vitro metabolic stability in human and mouse liver microsomes) in twelve matched pair analogs selected from our 6-substituted amiloride and HMA libraries. Mouse plasma stability, plasma protein binding, Caco-2 cell permeability, cardiac ion channel activity and pharmacokinetics in mice (PO and IV) and rats (IV) are described alongside amiloride and HMA comparators for a subset of the four most promising matched-pair analogs. The findings combined with earlier uPA activity/selectivity and other data ultimately drove selection of two analogs (AA1-39 and AA1-41) that showed efficacy in separate mouse cancer metastasis studies.
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Liern M, Colazo A, Vallejo G, Zotta E. Antiproteinuric action of amiloride in paediatric patient with corticoresistant nephrotic syndrome. Nefrologia 2021; 41:304-310. [PMID: 36166246 DOI: 10.1016/j.nefroe.2021.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Accepted: 11/19/2020] [Indexed: 06/16/2023] Open
Abstract
INTRODUCCION In nephrotic syndrome, increased podocyturia accompanies pathologic proteinuria. The therapeutic regimen with enalapril, losartan and amiloride could reduce both variables. OBJETIVES Evaluate the anti-proteinuric effect of 2 non-immunological therapeutic regimens, the quantitative relationship between podocyturia and proteinuria. MATERIAL AND METHODS We included children aged 4-12 years with corticoresistant nephrotic syndrome, using 2 different schemes: group A, enalapril + losartan, and group B, enalapril + losartan + amiloride. RESULTS In group A, 17 patients completed the study, the initial mean proteinuria was 39 mg/m2/h and mean proteinuria at the end was 24 mg/m2/h, while in group B 14 patients were treated and the initial average proteinuria was 36 mg/m2/h and the end average proteinuria was 13 mg/m2/h. The paired T test showed significant differences in the decrease in proteinuria, for patients in group B without variation in podocyturia. The 2 factors associated with an increase in proteinuria were podocyturia and the time elapsed from the diagnosis of cortico-resistant nephrotic syndrome to the start of treatment anti-proteinuric. CONCLUSIONS The use of amiloride decreased proteinuria, without significantly modifying podocyturia; we did not observe a positive relationship between both variables.
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Inoue M, Enomoto M, Yoshimura M, Mizowaki T. Pharmacological inhibition of sodium-calcium exchange activates NADPH oxidase and induces infection-independent NETotic cell death. Redox Biol 2021; 43:101983. [PMID: 33933883 PMCID: PMC8105669 DOI: 10.1016/j.redox.2021.101983] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 04/12/2021] [Accepted: 04/19/2021] [Indexed: 01/03/2023] Open
Abstract
In addition to its function of innate immunity against invading pathogens, neutrophil extracellular traps (NETs) promote thrombosis, autoimmune disease, and cancer metastasis; therefore, unnecessary exposure to the triggers of infection-independent NET generation should be avoided. We herein show that inhibition of forward-mode Na+/Ca2+ exchange by amiloride analogs, 5-(N-ethyl-N-isopropyl)amiloride (EIPA) and 5-(N-Methyl-N-isobutyl)amiloride (MIA), triggers NETotic cell death independently of infectious stimuli. Isolated human neutrophils treated with EIPA and MIA undergo NETotic cell death by an increase of intracellular Ca2+ following activation of NADPH oxidase and the resultant upregulation of intracellular ROS. EIPA- and MIA-mediated intracellular Ca2+ increase is attributed to the competitive binding of EIPA and MIA against Na+ to Na+/Ca2+ exchanger 1 (NCX1). These results demonstrate a new mechanism of infection-independent NET generation and implicate NCX1 as a physiologic regulator of intracellular calcium balance and NETotic cell death. Two of the amiloride analogs, EIPA and MIA, induce NETotic cell death without infectious stimuli. EIPA and MIA inhibit the forward-mode Na+/Ca2+ exchange and promote the intracellular Ca2+ overload. Intracellular Ca2+ overload by EIPA and MIA activates NADPH oxidase, elevates intracellular ROS level, and induces resultant NETotic cell death.
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Mandal AKJ, Wenban C, Heer RS, Kho J, Missouris CG. Covid-19, hypokalaemia and the renin-angiotensin-aldosterone system. Ann Med Surg (Lond) 2021; 65:102261. [PMID: 33815782 PMCID: PMC8003453 DOI: 10.1016/j.amsu.2021.102261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 03/24/2021] [Indexed: 11/16/2022] Open
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Liern M, Colazo A, Vallejo G, Zotta E. [Antiproteinuric action of amiloride in paediatric patient with corticoresistant nephrotic syndrome]. Nefrologia 2021; 41:304-310. [PMID: 33722403 DOI: 10.1016/j.nefro.2020.11.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 10/06/2020] [Accepted: 11/19/2020] [Indexed: 10/21/2022] Open
Abstract
INTRODUCCION In nephrotic syndrome, increased podocyturia accompanies pathologic proteinuria. The therapeutic regimen with enalapril, losartan and amiloride could reduce both variables. OBJETIVES Evaluate the anti-proteinuric effect of 2 non-immunological therapeutic regimens, the quantitative relationship between podocyturia and proteinuria. MATERIAL AND METHODS We included children aged 4 to 12 years with corticoresistant nephrotic syndrome, using 2 different schemes: group A, enalapril+losartan, and group B, enalapril+losartan+amiloride. RESULTS In group A, 17 patients completed the study, the initial mean proteinuria was 39mg/m2/h and mean proteinuria at the end was 24mg/m2/h, while in group B 14 patients were treated and the initial average proteinuria was 36mg/m2/h and the end average proteinuria was 13mg/m2/h. The paired T test showed significant differences in the decrease in proteinuria, for patients in group B without variation in podocyturia. The 2 factors associated with an increase in proteinuria were podocyturia and the time elapsed from the diagnosis of cortico-resistant nephrotic syndrome to the start of treatment anti-proteinuric. CONCLUSIONS The use of amiloride decreased proteinuria, without significantly modifying podocyturia; we did not observe a positive relationship between both variables.
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Fuchs FD, Scala LCN, Vilela-Martin JF, Whelton PK, Poli-de-Figueiredo CE, Pereira E Silva R, Gus M, Bortolotto LA, Consolim-Colombo FM, Schlatter RP, Cesarino JE, Castro I, Figueiredo Neto JA, Chaves H, Steffens AA, Alves JG, Brandão AA, de Sousa MR, Jardim PC, Moreira LB, Franco RS, Gomes MM, Afiune Neto A, Fuchs FC, Sobral Filho DC, Nóbrega AC, Nobre F, Berwanger O, Fuchs SC. Effectiveness of chlorthalidone/ amiloride versus losartan in patients with stage I hypertension and diabetes mellitus: results from the PREVER-treatment randomized controlled trial. Acta Diabetol 2021; 58:215-220. [PMID: 33047257 DOI: 10.1007/s00592-020-01611-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 09/23/2020] [Indexed: 12/21/2022]
Abstract
AIMS To compare the blood pressure (BP)-lowering efficacy of a chlorthalidone/amiloride combination pill with losartan, during initial management of JNC 7 Stage I hypertension in patients with type 2 diabetes mellitus. METHODS In an a priori subgroup analysis of a randomized, double-blind, controlled trial, volunteers aged 30-70 years, with stage I hypertension and diabetes mellitus, were randomized to 12.5/2.5 mg of chlorthalidone/amiloride (N = 47) or 50 mg of losartan (N = 50), and followed for 18 months in 21 clinical centers. If BP remained uncontrolled after three months, study medication dose was doubled, and if uncontrolled after six months, amlodipine (5 and 10 mg) and propranolol (40 and 80 mg BID) were added as open label drugs in a progressive fashion. RESULTS Systolic BP decreased to a greater extent in participants allocated to diuretics compared to losartan (P < 0.001). After 18 months of follow-up, systolic BP was 128.4 ± 10.3 mmHg in the diuretic group versus 133.5 ± 8.0 in the losartan group (P < 0.01). In the diuretic group, 36 out of 43 participants (83.7%) had a JNC 7 normal BP, compared to 31/47 (66%) in the losartan group (P = 0.089). Serum cholesterol was higher in the diuretic arm at the end of the trial. Other biochemical parameters and reports of adverse events did not differ by treatment. CONCLUSIONS Treatment of hypertension based on a combination of chlorthalidone and amiloride is more effective for BP lowering compared to losartan in patients with diabetes mellitus and hypertension. TRIAL REGISTRATION Clinical trials registration number: NCT00971165.
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Tang R, Ba G, Li M, Li Z, Ye H, Lin H, Zhang W. Evidence for role of acid-sensing ion channel 1a in chronic rhinosinusitis with nasal polyps. Eur Arch Otorhinolaryngol 2021; 278:2379-2386. [PMID: 33392760 DOI: 10.1007/s00405-020-06521-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 11/26/2020] [Indexed: 11/28/2022]
Abstract
PURPOSE A variety of inflammatory cells are infiltrated histologically in sinonasal mucosa of chronic rhinosinusitis with nasal polyps (CRSwNP), especially CRSwNP with asthma. Acid-sensing ion channel 1a (ASIC1a) is essential in the process of sensing acidification and triggering inflammation. Whereas, its role and mechanism in CRSwNP remain uncertain. The present study aimed to explore the roles and mechanism of ASIC1a in the pathogenesis of CRSwNP. METHODS Nasal secretions from control subjects, patients with CRSwNP with or without asthma were collected for measuring pH values. Western blotting, real-time PCR and immunohistochemistry (IHC) were employed to assess ASIC1a expression in nasal tissue samples from included subjects. The co-localization of ASIC1a with inflammatory cells was evaluated by immunofluorescence staining. Then, dispersed nasal polyp cells (DNPCs) were cultured under acidified condition (pH 6.0), with or without ASIC1a inhibitor amiloride. Western blotting, real-time PCR, LDH activity kit, and ELISA were performed to assess the effects and mechanisms of stimulators on the cells. RESULTS The pH values were significantly lower in the nasal secretions from patients with CRSwNP with asthma. Significant upregulation of ASIC1a protein, mRNA levels, and positive cells was found in CRSwNP with asthma. ASIC1a was detected in a variety of inflammatory cells. In cultured DNPCs, significant alterations of ASIC1a levels, LDH activity, HIF-1α levels, and inflammatory cytokines were found under acidified condition (pH 6.0), but were prevented by amiloride. CONCLUSION Upregulation of ASIC1a might be essential in the process of sensing acidification and triggering inflammatory response via enhancing HIF-1α expression and LDH activity to activate inflammatory cells in the pathogenesis of CRSwNP, especially in CRSwNP with asthma.
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Mellott A, Rockwood J, Zhelay T, Luu CT, Kaitsuka T, Kozak JA. TRPM7 channel activity in Jurkat T lymphocytes during magnesium depletion and loading: implications for divalent metal entry and cytotoxicity. Pflugers Arch 2020; 472:1589-1606. [PMID: 32964285 DOI: 10.1007/s00424-020-02457-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 08/26/2020] [Accepted: 08/28/2020] [Indexed: 12/14/2022]
Abstract
TRPM7 is a cation channel-protein kinase highly expressed in T lymphocytes and other immune cells. It has been proposed to constitute a cellular entry pathway for Mg2+ and divalent metal cations such as Ca2+, Zn2+, Cd2+, Mn2+, and Ni2+. TRPM7 channels are inhibited by cytosolic Mg2+, rendering them largely inactive in intact cells. The dependence of channel activity on extracellular Mg2+ is less well studied. Here, we measured native TRPM7 channel activity in Jurkat T cells maintained in external Mg2+ concentrations varying between 400 nM and 1.4 mM for 1-3 days, obtaining an IC50 value of 54 μM. Maintaining the cells in 400 nM or 8 μM [Mg2+]o resulted in almost complete activation of TRPM7 in intact cells, due to cytosolic Mg2+ depletion. A total of 1.4 mM [Mg2+]o was sufficient to fully eliminate the basal current. Submillimolar concentrations of amiloride prevented cellular Mg2+ depletion but not loading. We investigated whether the cytotoxicity of TRPM7 permeant metal ions Ni2+, Zn2+, Cd2+, Co2+, Mn2+, Sr2+, and Ba2+ requires TRPM7 channel activity. Mg2+ loading modestly reduced cytotoxicity of Zn2+, Co2+, Ni2+, and Mn2+ but not of Cd2+. Channel blocker NS8593 reduced Co2+ and Mn2+ but not Cd2+ or Zn2+ cytotoxicity and interfered with Mg2+ loading as evaluated by TRPM7 channel basal activity. Ba2+ and Sr2+ were neither detectably toxic nor permeant through the plasma membrane. These results indicate that in Jurkat T cells, entry of toxic divalent metal cations primarily occurs through pathways distinct from TRPM7. By contrast, we found evidence that Mg2+ entry requires TRPM7 channels.
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De Luca M, Ioele G, Grande F, Platikanov S, Tauler R, Ragno G. Photostability study of multicomponent drug formulations via MCR-ALS: The case of the hydrochlorothiazide- amiloride mixture. J Pharm Biomed Anal 2020; 186:113332. [PMID: 32387749 DOI: 10.1016/j.jpba.2020.113332] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/21/2020] [Accepted: 04/21/2020] [Indexed: 01/05/2023]
Abstract
The kinetics and photodegradation mechanism of the pharmaceutical mixture of hydrochlorothiazide (HCT) and amiloride (AML) has been studied in depth using a chemometric approach. Water solutions of HCT and AML, separately or in binary mixtures, were irradiated with forced light at different pH values (3, 7, 9 and 12). Multivariate Curve Resolution - Alternating Least Squares (MCR-ALS) modelling has been applied to the experimental data recorded by UV spectrophotometry and HPLC-UV/MS. 78 data sets were collected and their chemometric processing has allowed the simultaneous determination of the behaviour of the two drugs in the mixture when exposed to light and the dependence of their photodegradation kinetics on pH. MCR-ALS has been applied using three different implementations. Soft-MCR-ALS and hybrid Hard/Soft-MCR-ALS have been used to resolve the experimental data and to get the equilibrium and kinetic parameters of the investigated chemical processes. A third implementation of the MCR-ALS method has been used in the analysis of the incomplete data sets obtained when UV spectrophotometric and HPLC-UV/MS data were simultaneously analysed, using a row- and column-wise incomplete augmented data matrix arrangement. In these matrices, information from HPLC-UV detector was used as a bridge between the data recorded by UV spectrophotometry (acid-base and kinetic reactions monitoring) and the data obtained by HPLC-MS.
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Martins VM, Helal L, Ferrari F, Bottino LG, Fuchs SC, Fuchs FD. Efficacy of chlorthalidone and hydrochlorothiazide in combination with amiloride in multiple doses on blood pressure in patients with primary hypertension: a protocol for a factorial randomized controlled trial. Trials 2019; 20:736. [PMID: 31843024 PMCID: PMC6916111 DOI: 10.1186/s13063-019-3909-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 11/15/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Thiazide diuretics have demonstrated favorable blood pressure lowering efficacy, but the equivalent doses of their more common agents, chlorthalidone and hydrochlorothiazide, are still unclear. Further, concerns exist regarding adverse metabolic effects, which may be attenuated with the concomitant administration of a potassium-sparing diuretic, such as amiloride. This trial aims to investigate the efficacy of chlorthalidone and hydrochlorothiazide, in combination with amiloride at different doses, for initial management of patients with primary hypertension. METHODS/DESIGN This is a factorial (2 × 2) randomized double-blinded clinical trial comparing the association of a thiazide diuretic (chlorthalidone 25 mg/day or hydrochlorothiazide 50 mg/day) with a potassium-sparing diuretic (amiloride 10 mg/day or amiloride 20 mg/day) in patients with primary hypertension. The primary outcome will be the mean change from baseline in 24-h systolic and diastolic blood pressure measured by ambulatory blood pressure monitoring. The secondary outcomes will be the mean change from baseline in daytime and nighttime systolic and diastolic blood pressure measured by ambulatory blood pressure monitoring, mean change from baseline in systolic and diastolic blood pressure measured by office blood pressure, incidence of adverse events, variation of laboratory parameters, and proportion of patients who achieved blood pressure control. The follow-up will last 12 weeks. For a P alpha of 0.05, power of 80%, standard deviation of 9 mmHg, and absolute difference of 6 mmHg on systolic blood pressure on 24-h ambulatory blood pressure monitoring, it will be necessary to study a total of 76 patients. The sample size will be increased by 10% to compensate for losses, resulting in 84 patients being randomized. DISCUSSION Diuretics are pivotal drugs for the treatment of hypertension. Chlorthalidone and hydrochlorothiazide, in combination with amiloride in multiple doses, will be tested in terms of blood pressure lowering efficacy and safety. Since the intensity of blood pressure reduction is the major determinant of reduction in cardiovascular risk in hypertensive patients, this study will help to determine which combination of diuretics represents the most appropriate treatment for this population. TRIAL REGISTRATION ClinicalTrials.gov, NCT03928145. Registered on 25 April 2019. Last update on 29 April 2019.
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