Intravenous delivery of furosemide using lipid-based versus polymer-based nanocapsules: in vitro and in vivo studies.

OBJECTIVES: Furosemide (FSM), a potent loop diuretic, is used to treat edema due to hypertension, congestive heart failure, and liver and renal failures. FSM applications are limited by its low bioavailability. Our aim is to use different nanoencapsulation strategies to control the release of FSM and enhance its pharmacokinetic properties. METHODS: Two types of FSM-loaded nanocapsules, namely FSM-loaded lipid nanocapsules (LNCs) and polymeric nanocapsules (PNCs), were developed, physicochemically characterized, and subjected to pharmacokinetic and pharmacodynamic studies. Lipid nanocapsules were prepared by the simple phase inversion method using LabrafacTM lipid, while the polymeric nanocapsules were prepared by nanoprecipitation method using polycaprolactone polymer. RESULTS: Transmission electron microscopy ascertains spherical structures, corroborating the nanometric diameter of both types of nanocapsules. The particle size of the optimized FSM-loaded LNCs and FSM-loaded PNCs was 32.19 ± 0.72 nm and 230.7 ± 5.13 nm, respectively. The percent entrapment efficiency was 63.56 ± 1.40% of FSM for the optimized PNCs. The in vitro release study indicated prolonged drug release compared to drug solutions. The two loaded nanocapsules systems succeeded in enhancing the pharmacokinetic parameters in comparison to the marketed FSM solution with superior diuretic activity (p < 0.05). The results of the stability study and the terminal sterilization by autoclave indicated the superiority of LNCs over PNCs in maintaining the physical parameters under storage conditions and the drastic conditions of sterilization. CONCLUSIONS: LNCs and PNCs are considered promising nanosysems for improving the diuretic effect of FSM.

A Systematic Critical Review of Clinical Pharmacokinetics of Torasemide.

PURPOSE: Torasemide is a potassium-sparing loop diuretic used to treat fluid retention associated with congestive heart failure and kidney and hepatic diseases. This systematic review was conducted to combine all accessible data on the pharmacokinetics (PK) of torasemide in healthy and diseased populations, which may help clinicians avert adverse drug reactions and determine the correct dosage regimen. METHODS: Four databases were systematically searched to screen for studies associated with the PK of torasemide, and 21 studies met the eligibility criteria. The review protocol was registered in the PROSPERO database (CRD42023390178). RESULTS: A decrease in maximum plasma concentration (C max ) was observed for torasemide after administration of the prolonged-release formulation in comparison to that after administration of the immediate-release formulation, that is, 1.12 ± 0.17 versus 1.6 ± 0.2 mcg/mL. After administering an oral dose of torasemide, a 2-fold increase in the area under the concentration-time curve (AUC) was reported in patients with congestive heart failure compared with the healthy population. Moreover, the patients with renal failure (clearance < 30 mL/min) showed an increase in value of AUC 0-∞ that is, 42.9 versus 8.091 mcg.h -1 .mL -1 compared with healthy subjects. In addition, some studies have reported interactions with different drugs, in which irbesartan showed a slight increase in the AUC 0-∞ of torasemide, whereas losartan and empagliflozin did not. CONCLUSIONS: The current review summarizes all available PK parameters of torasemide that may be beneficial for avoiding drug-drug interactions in subjects with renal and hepatic dysfunction and for predicting doses in patients with different diseases.

Pharmacokinetics and diuretic effect of furosemide after single intravenous, oral tablet, and newly developed oral disintegrating film administration in healthy beagle dogs.

BACKGROUND: Furosemide, a diuretic that acts on the loop of Henle, is commonly used to treat congestive heart failure in veterinary medicine. Some owners have difficulty in administering oral tablet medication to animal patients, which leads to noncompliance, especially during long-term administration. Oral disintegrating film (ODF) has the advantages of easy administration via a non-invasive route, rapid dissolution, and low suffocating risk. The objective of this study was to research the pharmacokinetic (PK) profiles and diuretic effect of furosemide after intravenous (IV), orally uncoated tablet (OUT), and newly developed ODF administration in healthy beagle dogs. In this study, a furosemide-loaded ODF (FS-ODF) formulation was developed and five beagle dogs were administered a single dose (2 mg/kg) of furosemide via each route using a cross-over design. RESULTS: The most suitable film-forming agent was sodium alginate; thus, this was used to develop an ODF for easy drug administration. No significant differences were detected in the PK profiles between OUT and FS-ODF. In the blood profiles, the concentration of total protein was significantly increased compared to the baseline (0 h), whereas no significant difference was detected in the concentration of creatinine and hematocrit compared to the baseline. FS-ODF resulted in a similar hourly urinary output to OUT during the initial 2 h after administration. The urine specific gravity was significantly decreased compared to the baseline in each group. The peak times of urine electrolyte (sodium and chloride) excretion per hour were 1 h (IV), 2 h (OUT), and 2 h (FS-ODF). CONCLUSIONS: These results suggest that the PK/PD of furosemide after administration of newly developed FS-ODF are similar to those of OUT in healthy dogs. Therefore, the ODF formulation has the benefits of ease and convenience, which would be helpful to owners of companion animals, such as small dogs (< 10 kg), for the management of congestive heart failure.

[Diuretics as a problem-Pharmacokinetics, pharmacodynamics, use in edema or hypertension]. / Diuretika als Problem ­ Pharmakokinetik und -dynamik, Einsatz bei Ödemen oder Hypertonie.

BACKGROUND AND OBJECTIVE: Diuretics are key elements of the pharmacotherapy of diseases in internal medicine. Currently, they are particularly used in the treatment of edema and hypertension. For the treatment with diuretics some rules exist that help to improve the effectiveness and success. The article explains these rules, especially regarding combination treatment and meaningful dose escalation. Additionally, the side effects of treatment are critically discussed. RESULTS AND CONCLUSION: There is little evidence for the influence of diuretics in the treatment of edema on prognostic factors, such as mortality and comorbidities. For an improvement of the prognosis other substances are more important, e.g. angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers; however, diuretics in the treatment of hypertension show clear positive effects on the endpoints. In recent years a problem of side effects was demonstrated (skin cancer). Comparing the benefits regarding prognosis in the treatment of hypertension with the side effects, the administration but with appropriate protective measures seems to be warranted.

Profiling gene expression dynamics underpinning conventional testing approaches to better inform pre-clinical evaluation of an age appropriate spironolactone formulation.

There is a need to accelerate paediatric formulation evaluation and enhance quality of early stage data in drug development to alleviate the information pinch point present between formulation development and clinical evaluation. This present work reports application of DNA microarrays as a high throughput screening tool identifying markers for prediction of bioavailability and formulation driven physiological responses. With a focus on enhancing paediatric medicine provision, an oral liquid spironolactone suspension was formulated addressing a paediatric target product profile. Caco-2 cells cultured on transwell inserts were implemented in transport assays in vitro and DNA microarrays were used to examine gene expression modulation. Wistar rats were used to derive in vivo bioavailability data. In vitro, genomic, and in vivo data sets were concurrently evaluated linking drug transport and the genomic fingerprint generated by spironolactone formulation exposure. Significant changes in gene expression are reported as a result of formulation exposure. These include genes coding for ATP-binding cassette (ABC) transporters, solute carrier (SLC) transporters, cytochrome P450 (CYP) enzymes, and carboxylesterase enzymes. Genomic findings better inform pre-clinical understanding of pharmacokinetic and pharmacodynamic responses to spironolactone and its active metabolites than current in vitro drug transport assays alone.

Pharmacokinetics of Hydrochlorothiazide in Children: A Potential Surrogate for Renal Secretion Maturation.

Hydrochlorothiazide (HCTZ) is a thiazide diuretic used in adults and children for the treatment of hypertension and edema. The pharmacokinetic (PK) properties of HCTZ in children are not well characterized, particularly among children with obesity who frequently suffer from hypertension and may, therefore, benefit from HCTZ therapy. HCTZ is excreted in the kidney via organic anion transporters 1 and 3 (OAT1 and OAT3). The ontogeny of OAT1 and OAT3 remain unknown, but HCTZ clearance may serve as a surrogate marker of OAT1 and OAT3 maturation. Population PK modeling was performed in NONMEM, and the model was leveraged to conduct dose-exposure simulations. This study examined 83 plasma samples from 49 participants (69% male) taking enteral HCTZ. The median (range) postnatal age was 6.7 years (0.03-19.5 years), and 17 (34%) participants were obese or morbidly obese. The median (range) dose of HCTZ was 0.654 mg/kg (0.11-1.8 kg) and the median number of doses recorded per participant was 5 (1-8). HCTZ PK was well characterized by a 1-compartment PK model. Body weight and a maturation model based on postmenstrual age were significant covariates for apparent clearance, but the presence of obesity was not. Dosing simulations were performed with a standardized 1mg/kg. Simulated exposure (area under the curve and maximum HCTZ concentrations) decreased with age and was likely due to older children receiving the maximum absolute doses of HCTZ. Further studies with more patients in each age group are required to confirm these PK findings of HCTZ in the children.

Prediction of Kidney Drug Clearance: A Comparison of Tubular Secretory Clearance and Glomerular Filtration Rate.

BACKGROUND: Although proximal tubular secretion is the primary mechanism of kidney drug elimination, current kidney drug dosing strategies are on the basis of eGFR. METHODS: In a dedicated pharmacokinetic study to compare GFR with tubular secretory clearance for predicting kidney drug elimination, we evaluated stable outpatients with eGFRs ranging from 21 to 140 ml/min per 1.73 m2. After administering single doses of furosemide and famciclovir (metabolized to penciclovir), we calculated their kidney clearances on the basis of sequential plasma and timed urine measurements. Concomitantly, we quantified eight endogenous secretory solutes in plasma and urine using liquid chromatography-tandem mass spectrometry and measured GFR by iohexol clearance (iGFR). We computed a summary secretion score as the scaled average of the secretory solute clearances. RESULTS: Median iGFR of the 54 participants was 73 ml/min per 1.73 m2. The kidney furosemide clearance correlated with iGFR (r=0.84) and the summary secretion score (r=0.86). The mean proportionate error (MPE) between iGFR-predicted and measured furosemide clearance was 30.0%. The lowest MPE was observed for the summary secretion score (24.1%); MPEs for individual secretory solutes ranged from 27.3% to 48.0%. These predictive errors were statistically indistinguishable. Penciclovir kidney clearance was correlated with iGFR (r=0.83) and with the summary secretion score (r=0.91), with similar predictive accuracy of iGFR and secretory clearances. Combining iGFR with the summary secretion score yielded only modest improvements in the prediction of the kidney clearance of furosemide and penciclovir. CONCLUSIONS: Secretory solute clearance measurements can predict kidney drug clearances. However, tight linkage between GFR and proximal tubular secretory clearance in stable outpatients provides some reassurance that GFR, even when estimated, is a useful surrogate for predicting secretory drug clearances in such patients.

Amiloride: A review.

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.

Enhancing the Furosemide Permeability by Papain Minitablets Through a Triple Co-culture In Vitro Intestinal Cell Model.

The administration of medicines by the oral route is the most used approach for being very convenient. Although it is the most popular, this route also has absorption, and consequently, bioavailability limitations. In this sense, several pharmacotechnical strategies have been used to improve drug absorption, one of which is the use of permeation promoters. Papain is a very versatile plant enzyme that can be used as a permeation promoter of various active compounds. This study aimed to evaluate the safety of papain and the formulation of native papain minitablets to promote in vitro permeation of furosemide through an innovative biomimetic triple co-culture model of Caco-2, HT29-MTX, and Raji cells. Regarding permeation, furosemide and metaprolol concentrations are determined with HPLC; those are used to calculate Papp. Monolayer integrity was evaluated using TEER and Lucifer Yellow. In the presence of papain, TEER decreased two-fold and the Papp of furosemide increased six-fold. The results suggest that native papain minitablets can be used as therapeutic adjuvants to enhance the permeation of drugs significantly improving bioavailability.

Acetazolamide causes renal [Formula: see text] wasting but inhibits ammoniagenesis and prevents the correction of metabolic acidosis by the kidney.

Carbonic anhydrase (CAII) binds to the electrogenic basolateral Na+-[Formula: see text] cotransporter (NBCe1) and facilitates [Formula: see text] reabsorption across the proximal tubule. However, whether the inhibition of CAII with acetazolamide (ACTZ) alters NBCe1 activity and interferes with the ammoniagenesis pathway remains elusive. To address this issue, we compared the renal adaptation of rats treated with ACTZ to NH4Cl loading for up to 2 wk. The results indicated that ACTZ-treated rats exhibited a sustained metabolic acidosis for up to 2 wk, whereas in NH4Cl-loaded rats, metabolic acidosis was corrected within 2 wk of treatment. [Formula: see text] excretion increased by 10-fold in NH4Cl-loaded rats but only slightly (1.7-fold) in ACTZ-treated rats during the first week despite a similar degree of acidosis. Immunoblot experiments showed that the protein abundance of glutaminase (4-fold), glutamate dehydrogenase (6-fold), and SN1 (8-fold) increased significantly in NH4Cl-loaded rats but remained unchanged in ACTZ-treated rats. Na+/H+ exchanger 3 and NBCe1 proteins were upregulated in response to NH4Cl loading but not ACTZ treatment and were rather sharply downregulated after 2 wk of ACTZ treatment. ACTZ causes renal [Formula: see text] wasting and induces metabolic acidosis but inhibits the upregulation of glutamine transporter and ammoniagenic enzymes and thus suppresses ammonia synthesis and secretion in the proximal tubule, which prevented the correction of acidosis. This effect is likely mediated through the inhibition of the CA-NBCe1 metabolon complex, which results in cell alkalinization. During chronic ACTZ treatment, the downregulation of both NBCe1 and Na+/H+ exchanger 3, along with the inhibition of ammoniagenesis and [Formula: see text] generation, contributes to the maintenance of metabolic acidosis.

A Pilot Study of the Maternal-Fetal Pharmacokinetics of Furosemide in Plasma, Urine, and Amniotic Fluid of Hypertensive Parturient Women Under Cesarean Section.

The third trimester of pregnancy is related to physiological changes that can modify the process of absorption, distribution, metabolism, and excretion and, consequently, the efficacy and toxicity of drugs. However, little is known about furosemide pharmacokinetics and placental transfer in pregnancy. This study evaluated the maternal-fetal pharmacokinetics and distribution to amniotic fluid of furosemide in hypertensive parturient women under cesarean section. Twelve hypertensive parturient women under methyldopa (250 mg/8 h) and/or pindolol (10 mg/12 h) treatment received a 40-mg single oral dose of furosemide 1 to 10 hours before delivery by cesarean section. Blood and urine samples were collected for 12 hours after furosemide administration. At delivery, samples were obtained from maternal and umbilical cord blood (n = 8) to assess the transplacental transfer. Amniotic fluid (n = 4) was collected at the time of delivery. The following furosemide pharmacokinetic parameters were obtained as median (interquartile range): Cmax , 403 ng/mL (229 to 715 ng/mL); Tmax , 2.00 hours (1.50 to 4.83 hours); elimination half-life (t1/2 ), 2.50 hours (1.77 to 2.97 hours); AUC0-12 h , 1366 ng⋅h/mL (927 to 2531 ng⋅h/mL); AUC0-∞ , 1580 ng⋅h/mL (1270 to 2881 ng⋅h/mL); CL/F 25.3 L/h (13.8 to 31.4 L/h); CLR, 2.50 L/h (1.77 to 2.97 L/h); CLNR, 22.7 L/h (12.1 to 25.6 L/h); and Vd /F 82.8 L (34.4 to 173 L). The transplacental transfer of furosemide was 0.43 (0.10 to 0.73), and the amniotic fluid concentration was 11.0 ng/mL (5.51 to 14.6 ng/mL). From a clinical point of view, these results suggest that substrates of uridine diphosphate-glucuronosyltransferase isoenzymes such as furosemide may have increased clearance during pregnancy and could require dose adjustment in this population.

Subtherapeutic Acetazolamide Doses as a Noninvasive Method for Assessing Medication Adherence.

Adherence monitoring is a vital component of clinical efficacy trials, as the regularity of medication consumption affects both efficacy and adverse effect profiles. Pill-counts do not confirm consumption, and invasive plasma assessments can only assist post hoc assessments. We previously reported on the pharmacokinetics of a potential adherence marker to noninvasively monitor dosage consumption during a trial without breaking a blind. We reported that consumption cessation of subtherapeutic 15 mg acetazolamide (ACZ) doses showed a predictable urinary excretion decay that was quantifiable for an extended period. The current study describes the clinical implementation of 15 mg ACZ doses as an adherence marker excipient in distinct cohorts taking ACZ for different "adherence" durations. We confirm that ACZ output did not change (accumulate) during 18-20 days of adherence, and developed and assessed urinary cutoffs as nonadherence indicators. We demonstrate that whereas an absolute concentration cutoff (989 ng/mL) lacked sensitivity, a creatinine normalized equivalent (1,376 ng/mg ACZ) was highly accurate at detecting nonadherence. We also demonstrate that during nonadherent phases of three trials, creatinine-normalized urinary ACZ elimination was reproducible within and across trials with low variability. Excretion was first order, with a decay half-life averaging ~ 2.0 days. Further, excretion remained quantifiable for 14 days, providing a long period during which the date of last consumption might be determined. We conclude that inclusion of 15 mg ACZ as a dosage form adherence marker excipient, provides a reliable and sensitive mechanism to confirm medication consumption and detect nonadherence during clinical efficacy trials.

Empagliflozin in Heart Failure: Diuretic and Cardiorenal Effects.

BACKGROUND: Sodium-glucose cotransporter-2 inhibitors improve heart failure-related outcomes. The mechanisms underlying these benefits are not well understood, but diuretic properties may contribute. Traditional diuretics such as furosemide induce substantial neurohormonal activation, contributing to the limited improvement in intravascular volume often seen with these agents. However, the proximal tubular site of action of the sodium-glucose cotransporter-2 inhibitors may help circumvent these limitations. METHODS: Twenty patients with type 2 diabetes mellitus and chronic, stable heart failure completed a randomized, placebo-controlled crossover study of empagliflozin 10 mg daily versus placebo. Patients underwent an intensive 6-hour biospecimen collection and cardiorenal phenotyping at baseline and again after 14 days of study drug. After a 2-week washout, patients crossed over to the alternate therapy with the above protocol repeated. RESULTS: Oral empagliflozin was rapidly absorbed as evidenced by a 27-fold increase in urinary glucose excretion by 3 hours (P<0.0001). Fractional excretion of sodium increased significantly with empagliflozin monotherapy versus placebo (fractional excretion of sodium, 1.2±0.7% versus 0.7±0.4%; P=0.001), and there was a synergistic effect in combination with bumetanide (fractional excretion of sodium, 5.8±2.5% versus 3.9±1.9%; P=0.001). At 14 days, the natriuretic effect of empagliflozin persisted, resulting in a reduction in blood volume (-208 mL [interquartile range, -536 to 153 mL] versus -14 mL [interquartile range, -282 to 335 mL]; P=0.035) and plasma volume (-138 mL, interquartile range, -379 to 154±453 mL; P=0.04). This natriuresis was not, however, associated with evidence of neurohormonal activation because the change in norepinephrine was superior (P=0.02) and all other neurohormones were similar (P<0.34) during the empagliflozin versus placebo period. Furthermore, there was no evidence of potassium wasting (P=0.20) or renal dysfunction (P>0.11 for all biomarkers), whereas both serum magnesium (P<0.001) and uric acid levels (P=0.008) improved. CONCLUSIONS: Empagliflozin causes significant natriuresis, particularly when combined with loop diuretics, resulting in an improvement in blood volume. However, off-target electrolyte wasting, renal dysfunction, and neurohormonal activation were not observed. This favorable diuretic profile may offer significant advantage in the management of volume status in patients with heart failure and may represent a mechanism contributing to the superior long-term heart failure outcomes observed with these agents. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03027960.

Efficacy of furosemide-albumin compared with furosemide in critically ill hypoalbuminemia patients admitted to intensive care unit: a prospective randomized clinical trial.

BACKGROUND: Some physicians co-administer albumin with loop diuretics to overcome diuretic resistance in critically ill hypoalbuminemia patients, though previous studies have reported conflicting results on this matter. OBJECTIVE: The effects of adding albumin to furosemide to enhance its efficacy in critically ill hypoalbuminemia patients are evaluated. METHODS: This was a non-blinded randomized trial. 49 adult critically ill patients with hypoalbuminemia and generalized edema who received randomly furosemide and furosemide/albumin complex were enrolled. The patients' urine was collected at intervals of 2, 4, 6 and 8 h after initiation of the furosemide treatment, and the urine output and urinary excretion of furosemide and sodium were measured. The urinary excretion of furosemide was considered an indicator of drug efficacy. RESULTS: The amount of sodium and furosemide excreted in urine showed no significant differences between the two groups; however, the mean of the urinary excretion of furosemide in the first 2 h after drug infusion was significantly higher (p = 0.03) in the furosemide/albumin group. No significant correlation between APACHE II scores and serum albumin levels and the urinary excretion of furosemide was seen. CONCLUSION: The results indicated that there is not statistically significant differences between groups with furosemide alone and combined with albumin in urinary furosemide excretion. It seems that adding albumin for furosemide pharmacotherapy regime is not recommended as an intervention to increase furosemide efficacy in critically ill hypoalbuminemia patients. TRIAL REGISTRATION: IRCT with the registration number IRCT201412132582N12 in 23 February 2015; https://en.irct.ir/trial/2356 Graphical abstract.

Vanillin enhances the passive transport rate and absorption of drugs with moderate oral bioavailability in vitro and in vivo by affecting the membrane structure.

Vanillin is a popular flavoring agent in the food, tobacco, and perfume industries. In this paper, we investigated the effect of vanillin on the transport rates of drugs with different levels of permeability (acyclovir, hydrochlorothiazide, propranolol and carbamazepine) through a Caco-2 cell bidirectional transport experiment. We also explored the underlying mechanism using an in silico technique and fluorescence anisotropy measurements. The influence of vanillin on the pharmacokinetics of drugs whose transport rates were affected by vanillin in vitro was then studied in vivo. Results showed that vanillin (100 µM) increased the cumulative amount of passively transported drugs (2.1-fold of hydrochlorothiazide, 1.49-fold of propranolol, 1.35-fold of acyclovir, and 1.34-fold of carbamazepine) in vitro. Molecular dynamics simulations revealed that vanillin disordered the structure of the lipid bilayer and reduced the energy barrier of drugs across the center of the membrane. The anisotropy of TMA-DPH also decreased in Caco-2 cells after treatment with vanillin (25 and 100 µM) and indicated an increase in membrane fluidity, which was dose-dependent. An oral bioavailability study indicated that vanillin (100 mg kg-1) significantly enhanced the Cmax and AUC0-6 of hydrochlorothiazide by 1.42-fold and 1.28-fold, respectively, and slightly elevated the Cmax of propranolol. In conclusion, vanillin can significantly increase the absorption of drugs with moderate oral bioavailability in vitro and in vivo by loosening the membrane. Thus, the concurrent consumption of drugs with food containing vanillin may result in increased drug plasma concentration and pose potential health risks.

Impaired chloride homeostasis in epilepsy: Molecular basis, impact on treatment, and current treatment approaches.

Epilepsies represent one of the most common neurological diseases worldwide. They are characterized by recurrent spontaneous seizures with severe impact on a patient's life. An imbalance in excitatory and inhibitory signalling is considered the main underlying pathophysiological mechanism. Therefore, GABA-mimetic drugs, strengthening the main inhibitory signalling system in the CNS, are frequently used as antiepileptic or anticonvulsant drugs. However, the therapeutic effect of such treatment depends on the chloride gradient along the plasma membrane. Impairment of chloride homeostasis, caused by alterations in the functional balance of chloride transporters, was implicated in the pathophysiology of epilepsy and numerous other diseases. Breakdown or even inversion of the chloride gradient may result in ineffective or in worst cases proconvulsant effects of GABA-mimetics. Unfortunately, such situations are reported in considerable number. Consequently, bumetanide, an inhibitor of Na-K-Cl cotransporters gained interest as potential add-on therapy re-establishing the chloride gradient and thereby the hyperpolarizing effects of GABA-mimetic drugs. Indeed, preclinical studies yielded encouraging results, especially when applied in combination with GABA-mimetics in epilepsy models. However, bumetanide induces a strong diuretic effect and displays poor penetration across the blood-brain barrier, two adverse features for chronic antiepileptic treatment. Therefore, new compounds overcoming these limitations are under development. This review focuses on alterations in chloride homeostasis and its underlying molecular mechanisms in epilepsy, on the potential impact of impaired chloride homeostasis on the treatment of epilepsy and on concepts to overcome this problem including recent development of bumetanide derivatives with improved pharmacological profile.

A pilot randomised controlled trial evaluating the pharmacodynamic effects of furosemide versus acetazolamide in critically ill patients.

OBJECTIVE: To compare the physiological and biochemical effects of a single intravenous dose of furosemide or acetazolamide in critically ill patients. DESIGN: Single centre, pilot randomised controlled trial. SETTING: Large tertiary adult intensive care unit (ICU). PARTICIPANTS: Twenty-six adult ICU patients deemed to require diuretic therapy. INTERVENTION: Single dose of intravenous 40 mg furosemide or 500 mg acetazolamide. MAIN OUTCOME MEASURES: Data were collected on urine output, cumulative fluid balance, and serum and urine biochemistry for 6 hours before and 6 hours after diuretic administration. RESULTS: Study patients had a median age of 55 years (IQR, 50-66) and median APACHE III score of 44 (IQR, 37-52). Furosemide caused a much greater increase in-urine output and much greater median mass chloride excretion (121.7 mmol [IQR, 81.1-144.6] v 23.3 mmol [IQR, 20.4-57.3]; P < 0.01) than acetazolamide. Furosemide also resulted in a progressively more negative fluid balance while acetazolamide resulted in greater alkalinisation of the urine (change in median urinary pH, +2 [IQR, 1.75-2.12] v 0 [IQR, 0-0.5]; P = 0.02). In keeping with this effect, furosemide alkalinised and acetazolamide acidified plasma (change in median serum pH, +0.03 [IQR, 0.01-0.04] v -0.01 [IQR, -0.04 to 0]; P = 0.01; change in median serum HCO3-, +1.5 mmol/L [IQR, 0.75-2] v -2 mmol/L [IQR, -3 to 0]; P < 0.01). CONCLUSIONS: Furosemide is a more potent diuretic and chloriuretic agent than acetazolamide in critically ill patients, and achieves a threefold greater negative fluid balance. Compared with acetazolamide, furosemide acidifies urine and alkalinises plasma. Our findings imply that combination therapy might be a more physiological approach to diuresis in critically ill patients.

Pharmacokinetic Interaction Among Telmisartan, Amlodipine, and Hydrochlorothiazide After a Single Oral Administration in Healthy Male Subjects.

PURPOSE: Hypertension is a major risk factor for cardiovascular diseases, necessitating hypertension control. Antihypertensive drugs are more potent when administered in combinations of 2 or 3 different classes of drugs. One such therapy includes a combination of an angiotensin receptor blocker, a calcium channel blocker, and a diuretic. The objective of this study was to evaluate the pharmacokinetic interaction among telmisartan, amlodipine, and hydrochlorothiazide. METHODS: A randomized, open-label, 3-period, 6-sequence, 3-treatment, single-dose crossover study was conducted in healthy male subjects. Subjects were randomly assigned to 1 of 6 sequences and one of the following treatments was administered in each period: treatment A, co-administration of one tablet of telmisartan 80 mg and one tablet of amlodipine 10 mg; treatment B, one tablet of hydrochlorothiazide 25 mg alone; and treatment C, co-administration of all 3 investigational products. Serial blood samples were collected up to 144 hours postdose. Plasma drug concentrations were measured by using LC/MS-MS. Pharmacokinetic parameters, including Cmax and AUC0-last, were determined by using noncompartmental analysis. The geometric least squares mean ratios and associated 90% CIs of log-transformed Cmax and AUC0-last for separate administration or co-administration were calculated to evaluate pharmacokinetic interactions. FINDINGS: Twenty-seven subjects completed the study. The geometric least squares mean ratios and 90% CIs of Cmax and AUC0-last were 1.02 (0.85-1.21) and 1.04 (0.97-1.13) for telmisartan; 1.00 (0.95-1.04) and 0.95 (0.91-0.99) for amlodipine; and 0.88 (0.82-0.96) and 0.86 (0.82-0.90) for hydrochlorothiazide, respectively. No serious adverse events were recorded, and all reported adverse events were of mild intensity. IMPLICATIONS: The pharmacokinetic parameters of telmisartan, amlodipine, and hydrochlorothiazide when administered separately or co-administered were compared, and all the parameters met the criteria for pharmacokinetic equivalence. Combination therapy of these 3 drugs had no significant impact on the pharmacokinetic parameters of each drug. (ClinicalTrials.gov Identifier: NCT03889145).

Pharmacodynamics of 250 mg and 500 mg oral furosemide in peritoneal dialysis
.

Residual renal function and diuresis preservation are associated with improved volume control and lower mortality in peritoneal dialysis (PD). Loop diuretics are used to maintain diuresis, although their optimal dosage remains unclear. This study aimed to compare the pharmacodynamics of a 250-mg and a 500-mg dose of oral furosemide in PD patients. 12 patients with a diuresis > 100 mL per day were randomized in a crossover pattern to successively receive an oral dose of 250 mg and 500 mg of furosemide. Twelve-hour natriuresis and diuresis were measured before and after each furosemide dose. Fractional excretion of sodium (FENa) and absolute sodium excretion increased after each dose, although these rises were not statistically significantly different (5.8% (250 mg) vs. 6.9% (500 mg), p = 0.57 for FENa and 42.6 mmol/12h (250 mg) vs. 70.8 mmol/12h (500 mg), p = 0.07 for absolute sodium excretion). Urinary volume was significantly increased after the 500-mg dose, whilst the difference did not reach statistical significance after the 250-mg dose. Furthermore, the higher dose was associated with a greater increase in diuresis than the lower dose (226 mL (250 mg) vs. 522 mL (500 mg), p = 0.04). Furosemide could be used at oral single doses reaching 500 mg in PD patients requiring greater volume control.