Pharmacokinetics and effects of frusemide in patients with the nephrotic syndrome

Diuretic effect of co-administration of furosemide and albumin in comparison to furosemide therapy alone: An updated systematic review and meta-analysis

BACKGROUND

It has been a matter of much debate whether the co-administration of furosemide and albumin can achieve better diuresis and natriuresis than furosemide treatment alone. There is inconsistency in published trials regarding the effect of this combination therapy. We, therefore, conducted this meta-analysis to explore the efficacy of furosemide and albumin co-administration and the factors potentially influencing the diuretic effect of such co-administration.

METHODS

In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we searched the PubMed, Embase, Medline, and Cochrane databases. Prospective studies with adult populations which comparing the effect of furosemide and albumin co-administration with furosemide alone were included. The outcomes including diuretic effect and natriuresis effect measured by hourly urine output and hourly urine sodium excretion from both groups were extracted. Random effect model was applied for conducting meta-analysis. Subgroup analysis and sensitivity analysis were performed to explore potential sources of heterogeneity of treatment effects.

RESULTS

By including 13 studies with 422 participants, the meta-analysis revealed that furosemide with albumin co-administration increased urine output by 31.45 ml/hour and increased urine excretion by 1.76 mEq/hour in comparison to furosemide treatment alone. The diuretic effect of albumin and furosemide co-administration was better in participants with low baseline serum albumin levels (< 2.5 g/dL) and high prescribed albumin infusion doses (> 30 g), and the effect was more significant within 12 hours after administration. Diuretic effect of co-administration was better in those with baseline Cr > 1.2 mg/dL and natriuresis effect of co-administration was better in those with baseline eGFR < 60 ml/min/1.73m2.

CONCLUSION

Co-administration of furosemide with albumin might enhance diuresis and natriuresis effects than furosemide treatment alone but with high heterogeneity in treatment response. According to the present meta-analysis, combination therapy might provide advantages compared to the furosemide therapy alone in patients with baseline albumin levels lower than 2.5 g/dL or in patients receiving higher albumin infusion doses or in patients with impaired renal function. Owing to high heterogeneity and limited enrolled participants, further parallel randomized controlled trials are warranted to examine our outcome.

REGISTRATION

PROSEPRO ID: CRD42020211002; https://clinicaltrials.gov/.

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.

Human albumin infusion for treating oedema in people with nephrotic syndrome

BACKGROUND

Oedema is a common clinical symptom in people with nephrotic syndrome and human albumin has been widely used in the treatment of oedema by increasing vascular volume and this inducing diuresis. It may be used with or without diuretics such as furosemide. However, the quantitative contribution of human albumin in treating oedema is not fully understood. If human albumin were found to be effective and safe in the treatment of oedema, it could help clinicians to develop therapeutic strategies to improve the management of diuretic resistance associated with nephrotic syndrome.

OBJECTIVES

This review aimed to examine the benefits and harms of human albumin infusion for treating oedema associated with nephrotic syndrome.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 23 June 2019 through contact with the Information Specialists using search terms relevant to this review. Studies in the Specialised Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs evaluating the effect of human albumin infusion compared with placebo or no intervention, human albumin with diuretics compared with diuretic alone, human albumin compared with diuretics and other treatments, clinical outcomes, death, quality of life, kidney function and adverse effects in people with nephrotic syndrome. We excluded cross-over studies but data for the first period was to be included if available.

DATA COLLECTION AND ANALYSIS

Standard methods of the Cochrane Collaboration were used. Two authors independently assessed eligibility, risk of bias, study quality and extracted data. We calculated mean difference (MD) for continuous data with 95% confidence intervals (CI). We assessed the certainty of the evidence using GRADE.

MAIN RESULTS

One study met our inclusion criteria (26 children with minimal change nephrotic syndrome) and 11 were excluded (nine cross-over studies, one where albumin was not used for nephrotic syndrome and one where authors did not state whether the children had oedema). Risk of bias for the included study was unclear for selection bias, high for performance and detection bias, low for attrition bias, and high for selective reporting. The included study compared albumin plus furosemide with an equal volume of dextrose. Of our prespecified outcomes, the authors reported clinical improvement as weight change, serum sodium and adverse outcomes (blood pressure). The authors reported a greater weight loss in the albumin treated group initially but no difference overall at 10 days. However, the data in the text and the figures were inconsistent so we could not confirm the authors statements (very low certainty evidence). It is uncertain whether albumin infusion improves serum sodium when compared with an equal volume of dextrose (MD 2.00 mEq/L, 95% CI -0.09 to 4.09), systolic blood pressure (MD 2.00 mmHg, 95% CI -3.52 to 7.52) or diastolic blood pressure (MD 2.00 mmHg, 95%CI -4.29 to 8.29). Death, quality of life, and kidney function were not reported.

AUTHORS' CONCLUSIONS

We identified only one small study that was relevant to our review, therefore we are unable to draw any conclusions regarding the use of human albumin with or without diuretics in nephrotic syndrome. More RCTs are needed.

Treatment of Disorders of Sodium Balance in Chronic Kidney Disease

Extracellular fluid volume expansion is nearly universal in patients with CKD. Such volume expansion has features similar to the syndrome of heart failure with preserved ejection fraction, which not only leads to symptoms but can also lead to further organ damage. Unique treatment challenges are present in this patient population, including low glomerular filtration, which limits sodium chloride filtration, intrinsic tubule predisposition to sodium chloride retention, and proteinuria. In addition, pharmacokinetic considerations alter the disposition of diuretics in patients with CKD and nephrotic syndrome. Maintaining extracellular fluid volume near to normal is often necessary for hypertension treatment in this population, but it may also help prevent progressive cardiovascular and kidney damage. Although powerful diuretics can often accomplish this goal, this often comes at a cost of competing adverse effects. An approach to reduce extracellular fluid volume while avoiding adverse effects, therefore, requires a nuanced yet aggressive therapeutic approach.

Co-administration of furosemide with albumin for overcoming diuretic resistance in patients with hypoalbuminemia: a meta-analysis

PURPOSE

To systematically review clinical studies of co-administration of albumin and loop diuretics in hypoalbuminemic patients as a strategy to overcome diuretic resistance.

MATERIALS AND METHODS

Systematic search of electronic databases up to October 2012. We included randomized clinical trials of adults with hypoalbuminemia, comparing co-administration of loop diuretics and albumin versus loop diuretics alone. Quantitative data were synthesized with meta-analytic techniques for clinical, surrogate (urinary volume and urinary sodium excretion) and intermediate (pharmacokinetic and hemodynamic parameters) outcomes.

RESULTS

Ten studies were included, of which 8 trials with crossover design were synthesized with meta-analysis. A statistically significant increase in the amount of urine volume (increment of 231 mL [95% confidence interval 135.5-326.5]) and sodium excreted (15.9 mEq [4.9-26.8]) at 8 hours were found in favor of co-administration of albumin and furosemide. These differences were no longer statistically significant at 24 hours. Meta-analyses for intermediate outcomes (ie, furosemide excretion, distribution volume etc.) did not reveal statistically significant differences.

CONCLUSIONS

Synthesis of a heterogeneous body of evidence shows transient effects of modest clinical significance for co-administration of albumin with furosemide in hypoalbuminemic patients. Pragmatic, large-scale randomized studies are needed to delineate the role of this strategy.

The added-up albumin enhances the diuretic effect of furosemide in patients with hypoalbuminemic chronic kidney disease: a randomized controlled study

Background

Chronic kidney disease (CKD) with edema is a common clinical problem resulting from defects in water and solute excretion. Furosemide is the drug of choice for treatment. In theory, good perfusion and albumin are required for the furosemide to be secreted at the tubular lumen. Thus, in the situation of low glomerular filtration rate (GFR) and hypoalbuminemia, the efficacy of furosemide alone might be limited. There has been no study to validate the effectiveness of the combination of furosemide and albumin in this condition.

Methods

We conducted a randomized controlled crossover study to compare the efficacy of diuretics between furosemide alone and the combination of furosemide plus albumin in stable hypoalbuminemic CKD patients by measuring urine output and sodium. The baseline urine output/sodium at 6 and 24 hours were recorded. The increment of urine output/sodium after treatment at 6 and 24 hours were calculated by using post-treatment minus baseline urine output/sodium at the corresponding period.

Results

Twenty-four CKD patients (GFR = 31.0 ± 13.8 mL/min) with hypoalbuminemia (2.98 ± 0.30 g/dL) were enrolled. At 6 hours, there were significant differences in the increment of urine volume (0.47 ± 0.40 vs 0.67 ± 0.31 L, P < 0.02) and urine sodium (37.5 ± 29.3 vs 55.0 ± 26.7 mEq, P < 0.01) between treatment with furosemide alone and with furosemide plus albumin. However, at 24 hours, there were no significant differences in the increment of urine volume (0.49 ± 0.47 vs 0.59 ± 0.50 L, P = 0.46) and urine sodium (65.3 ± 47.5 vs 76.1 ± 50.1 mEq, P = 0.32) between the two groups.

Conclusion

The combination of furosemide and albumin has a superior short-term efficacy over furosemide alone in enhancing water and sodium diuresis in hypoalbuminemic CKD patients.

Trial registration

The Australian New Zealand Clinical Trials Registration (ANZCTR12611000480987)

Treatment of severe edema in children with nephrotic syndrome with diuretics alone--a prospective study

BACKGROUND AND OBJECTIVE

Severe edema in children with nephrotic syndrome (NS) may be associated with volume contraction (VC) or volume expansion (VE). Usually, severe edema in children is treated with intravenous (IV) albumin and diuretics, which is appropriate for VC patients. However, in VE patients, this can precipitate fluid overload. The objective of this study was to evaluate treatment of severe edema in NS with diuretics alone.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Thirty NS patients with severe edema were enrolled in this prospective study in two phases. VC was diagnosed based on fractional excretion of sodium (FeNa) <1%. VC patients received IV albumin and furosemide. VE patients received IV furosemide and oral spironolactone. On the basis of phase 1 observations, FeNa <0.2% identified VC in 20 phase 2 patients.

RESULTS

All phase 1 patients had FeNa <1%. Phase 1 patients when reanalyzed based on a FeNa cutoff of 0.2%; it was noted that VC patients had higher BUN, BUN/creatinine ratio, urine osmolality, and lower FeNa and urine sodium compared with VE patients. Similar results were observed in phase 2. VC patients had significantly higher renin, aldosterone, and antidiuretic hormone levels. In phase 2, 11 VE patients received diuretics alone and 9 VC patients received albumin and furosemide. There was no difference in hospital stay and weight loss in VC and VE groups after treatment.

CONCLUSIONS

FeNa is useful in distinguishing VC versus VE in NS children with severe edema. The use of diuretics alone in VE patients is safe and effective.

Urinary protein binding does not affect response to furosemide in patients with nephrotic syndrome

Response to loop diuretics in patients with nephrotic syndrome (NS) is subnormal. Studies in animal models of NS have suggested that binding of diuretic to urinary albumin is one of the mechanisms that may be operative in this diuretic resistance. To explore this hypothesis, 12 patients with NS were studied to determine whether displacement from urinary protein binding with sulfisoxazole would restore response to 120 mg of furosemide. The study was stopped after treating seven patients because it was clear that sulfizoxazole had no effect. Sodium excretion (mean +/- SD) from furosemide alone was 239 +/- 90 versus 240 +/- 115 mEq/8 h with sulfisoxazole. Sulfisoxazole had modest effects on serum pharmacokinetics of furosemide but had no effect on either the time course of furosemide urinary excretion or overall amount excreted: 49 +/- 15 mg versus 54 +/- 12 mg for furosemide alone and furosemide plus sulfisoxazole, respectively. It is concluded that urinary protein binding of loop diuretics is not a major mechanism for the diuretic resistance of NS. In turn, strategies aimed at displacing such binding are unlikely to be clinically helpful.

Clinical consequences of the biphasic elimination kinetics for the diuretic effect of furosemide and its acyl glucuronide in humans

This review discusses the possibility of whether furosemide acyl glucuronide, a metabolite of furosemide, contributes to the clinical effect of diuresis. First an analytical method (e.g. HPLC) must be available to measure both parent drug and furosemide acyl glucuronide. Then, with correctly treated plasma and urine samples (light protected, pH 5) from volunteers and furosemide-treated patients, the kinetic curves of both furosemide as well as its acyl glucuronide can be measured. The acyl glucuronide is formed in part by the kidney tubules and it is possible that the compound is pharmacologically active through inhibition of the Na+/2Cl-/K+ co-transport system; up to now the mechanism of action has been solely attributed to furosemide. The total body clearance of furosemide occurs by hepatic and renal glucuronidation (50%) and by renal excretion (50%). Enterohepatic cycling of furosemide acyl glucuronide, followed by hydrolysis, results in a second and slow elimination phase with a half-life of 20-30 h. This slow elimination phase coincides with a pharmacodynamic rebound phase of urine retention. After each dosage of furosemide, there is first a short stimulation of urine flow (4 h), which is followed by a 3-day recovery period of the body. The following clinical implications arise from study of the elimination kinetics of furosemide. Repetitive dosing must result in accumulation of the recovery period. Accumulation of furosemide and its acyl glucuronide in patients with end-stage renal failure results from infinite hepatic cycling. Impaired kidney function may result in impaired glucuronidation and diuresis. While kidney impairment normally requires a dose reduction for those compounds which are mainly eliminated by renal excretion, for diuretics, a dose increment is required in order to maintain a required level of diuresis. The full clinical impact of the accumulation of furosemide and its acyl glucuronide in patients with end-stage renal failure has to be determined.

Coadministration of albumin and furosemide in patients with the nephrotic syndrome

BACKGROUND

In patients with nephrotic syndrome, the natriuretic effect of furosemide (FU) is diminished. The effect of coadministration of FU and human albumin (HA) has remained controversial.

METHODS

In a double-blind, placebo-controlled study, nine nephrotic patients (six males, 48 +/- 4 years) on standardized sodium chloride intake, in random order on three separate days, received by intravenous administration for 60 minutes either (a) 60 mg FU plus a sham infusion, (b) 60 mg FU plus 200 ml of a 20% solution of HA, or (c) sham infusion plus 200 ml of a 20% solution of HA. Urinary volume, sodium, albumin and FU excretion, renal hemodynamics, and plasma atrial natriuretic factor concentration were assessed.

RESULTS

Administration of FU alone significantly (P < 0.01) increased mean cumulative urinary sodium (259 +/- 30 mmol) and volume excretion (2684 +/- 167 ml) in the first eight hours as compared with the HA infusion alone (118 +/- 12 mmol, 1827 +/- 141 ml). The coadministration of FU and HA caused an even more marked increase (P < 0.01 vs. HA alone) of urinary sodium (312 +/- 28 mmol) and volume excretion (3230 +/- 201 ml); the difference to FU administration alone was significant (P < 0.05). Plasma atrial natriuretic factor, serum albumin concentration, and urinary albumin excretion increased significantly on both HA infusion days, whereas urinary excretion of FU remained unchanged with HA coadministration. Glomerular filtration rate (CIn) was not significantly affected by any of the infusion protocols, but effective renal plasma flow (CPAH) increased significantly on both HA infusion days.

CONCLUSIONS

Coadministration of HA potentiates the action of FU in patients with the nephrotic syndrome, but only modestly. This effect is mediated by changes in renal hemodynamics.

Changes in renal clearance of furosemide due to changes in renal blood flow and plasma albumin concentration

We have shown that, within therapeutic plasma concentrations, the unbound fraction of furosemide changes in direct proportion to the reciprocal of the plasma albumin concentration (correlation coefficient 0.99). Changes in the albumin concentration were produced by ultrafiltration of human plasma using a haemofiltration filter. Thus, we propose that, when studying changes in the pharmacokinetics of a highly protein bound drug, calculated changes in the unbound fraction offer an alternative to actual measurement of the unbound concentration, which is often difficult. Nine healthy volunteers receiving a continuous furosemide infusion were studied in normovolaemia and after dehydration (-1.4 kg), with and without pretreatment with an angiotensin converting enzyme inhibitor (captopril) or an a1-adrenoceptor blocking agent (prazosin). Significantly larger changes in the renal clearance of furosemide were found that could be explained by changes in the unbound fraction. Following dehydration, the unbound fraction of furosemide was decreased by about 5%, while its renal clearance fell by 27%, 33% and 13% after pretreatment with placebo, captopril and prazosin, respectively. The secretory clearance of the unbound furosemide changed substantially and in parallel with changes in the renal blood flow. It is suggested that changes in the renal clearance and excretion of furosemide and its t1/2 are much more dependent on changes in renal blood flow than on changes in its unbound fraction.

Physiological modelling of renal drug clearance

A physiological model of renal drug clearance is presented with the aim of establishing a basis for adjusting drug dosing regimens in renal insufficiency. In agreement with the morphology of blood supply to the nephron, the model assumes serial arrangement of the processes involved in drug excretion. Fractional extraction by filtration in the glomeruli is defined in terms of the product of the unbound fraction of the drug, the filtration fraction being responsible for the limited extraction efficiency of this process. For a description of the limitations of the tubular secretory process by plasma flow through peritubular capillaries, the parallel tube model is utilized. The assumption of direct proportionality between the transport maximum of the secretory process and filtrate flow in the tubules permits a quantitative comparison of the intrinsic tubular secretion clearance and the effectiveness of the filtration process. Provided that the secretory mechanism is highly effective, renal clearance becomes dependent only on kidney plasma flow and the fraction of drug not reabsorbed in the tubules. Tubular reabsorption results only in a proportional decrease in renal clearance. The model predicts proportionality of renal drug clearance to GFR, which as a rule is used for dosage adjustment of drugs in renal insufficiency, only for compounds exclusively excreted by filtration. Compounds also excreted by tubular secretion in general exhibit a curvilinear relationship. The curvature is less pronounced as an increasing fraction of the drug is protein bound in blood. Therefore, for dosage adjustment of drugs secreted in the tubules and highly bound in blood, proportionality between renal clearance and GFR can serve as a reasonable approximation.(ABSTRACT TRUNCATED AT 250 WORDS)

Elucidating the relationship between acetazolamide plasma protein binding and renal clearance using an albumin infusion

The effect of plasma protein binding changes on drug clearance is an important concept in clinical pharmacology. In a hypoalbuminemic patient receiving acetazolamide, albumin infusion (50 g) increased acetazolamide plasma protein binding towards normal as the serum albumin concentration rose (r = 0.91, P < .001). The ratio of acetazolamide renal plasma clearance to creatinine clearance decreased as serum albumin levels increased (r = 0.78, P < .05) and the unbound drug fraction fell (r = 0.88, P < .01), but clearance ratios based on unbound plasma acetazolamide levels did not change. Albumin infusion resulted in a nonparallel decline over time between plasma and unbound plasma acetazolamide concentrations. These data demonstrate that, over the range of observed serum albumin concentrations, acetazolamide renal plasma clearance is sensitive to changes in plasma protein binding. Furthermore, our findings emphasize the importance of measuring unbound drug levels when protein binding changes occur during the course of drug disposition studies. Finally, this methodology allows for the fascile assessment of the effects of plasma protein binding changes on renal drug clearance.

Response to furosemide during dehydration with and without naproxen pretreatment of kidney donors and renal transplant recipients

The response to 40 mg furosemide p.o. in 6 healthy kidney donors and 6 renal transplant recipients with and without naproxen pretreatment has been studied. No volume replacement was given in order to study the development of tolerance. The subjects showed an average dehydration of 1.5 kg.6 h-1. While mean creatinine clearance was equal in patients and donors (76 vs 80 ml/min), renal furosemide clearance was significantly lower in the patients (47 vs 81 ml min; P less than 0.05). The patients also excreted a smaller fraction of the dose in the urine (5.7 vs 7.8 mg/6 h; P less than 0.05). As the overall renal sensitivity was similar in the two groups, the natriuretic response was correspondingly smaller in transplant recipients as compared to donors. Within the observation period of 6 h after dosing, acute tolerance developed in the donors and in 4 of the 6 patients, as shown by clockwise hysteresis in the dose (urine furosemide excretion rate)-response (natriuresis) curves. Pretreatment with naproxen reduced renal sensitivity to furosemide (right shift of the dose response curve) in all the donors but in only 2 of the patients. In both groups acute tolerance was less pronounced after naproxen, which may indicate involvement of the prostaglandin system in the development of acute tolerance. The results may also indicate regeneration of sympathetic nerves with functional capacity in at least some renal transplants, or that other mechanisms of salt regulation compensate for loss of sympathetic nerve activity.