The Effect of Tolvaptan on Metabolism and Electrolyte Homeostasis in Patients with Heart Failure: A Systematic Review and Meta-Analysis.

Background: This study aimed to investigate the effect of tolvaptan on metabolism and electrolyte homeostasis in patients with heart failure (HF). Methods: Literature databases, such as PubMed, EMBASE, the Cochrane Library, China National Knowledge Infrastructure, VIP, and WanFang Data, were systematically searched for relevant trials from inception to November 4, 2023. We used the fixed effect model to combine the effect sizes and used I2 to test heterogeneity. Funnel plots were plotted to assess publication bias. Results: 16 studies were eligible for further analysis. No significant differences were identified in the incidence of hyperuricemia between the tolvaptan group and the placebo group (odds ratio (OR) = 1.23, 95% confidence interval (CI) = 0.97 to 1.55, p = 0.09). Tolvaptan decreased the levels of blood uric acid compared to traditional diuretics (mean difference (MD) = -82.8, 95% CI = -96.48 to -69.13, p < 0.00001). There was no significant difference in hypernatremia (OR = 1.62, 95% CI = 0.66 to 3.96, p = 0.29) and hyperkalemia (OR = 1.17, 95% CI = 0.93 to 1.48, p = 0.18) between the tolvaptan and control groups. Conclusions: Tolvaptan reduced the level of blood uric acid compared to conventional diuretics, and could be used as a substitute for traditional diuretics for HF patients with a high risk of gout.

Evaluating the Safety and effectivenesS in adult KorEaN patients treated with Tolvaptan for management of autosomal domInAnt poLycystic kidney disease (ESSENTIAL): final report.

Background: Tolvaptan, a selective vasopressin V2 receptor antagonist, was first approved by the Korean Ministry of Food and Drug Safety in 2015 as a treatment option for autosomal dominant polycystic kidney disease (ADPKD). To prescribe tolvaptan safely and effectively, we designed the phase 4 clinical trial among Korean ADPKD patients with chronic kidney disease stages 1 to 3. Methods: A total of 117 Korean patients aged 19 to 50 years with rapidly progressing ADPKD were enrolled in the study. Tolvaptan was prescribed for 24 months with the maximum tolerable dose up to 120 mg/day. The primary outcome was the incidence of treatment-emergent adverse events (TEAEs) including hepatic adverse events. The secondary outcomes were the annual mean percent change of total kidney volume (TKV) and the annual mean change of estimated glomerular filtration rate (eGFR). Results: A total of 489 TEAEs occurred in 106 patients (90.6%). A total of 17 cases of hepatic adverse events (14.5%) occurred during the study period and mostly within the first 18-month period. However, liver enzymes were normalized after drug discontinuation. Although it was not statistically significant, patients with a previous history of liver disease as well as those with mild elevation of liver enzyme showed a higher frequency of hepatic adverse events. Compared with the predicted value from the calculation, tolvaptan attenuated both TKV growth and eGFR decline rate. Conclusion: Although the incidence of hepatic adverse events was higher in Korean ADPKD patients compared to the previous studies, tolvaptan can be prescribed safely and effectively using meticulous titration and 1-month interval monitoring.

A case report: pitfalls in antibacterial therapy with rifampicin for mechanical valve endocarditis-the king of drug interactions.

Background: Rifampicin is a strong inducer of the hepatic cytochrome P450 (CYP) family and is known to interact with many clinical drugs. However, to our knowledge, no case of worsening heart failure (HF) due to the interaction between rifampicin and HF drugs has been reported. Case summary: A 32-year-old female, who had undergone intracardiac repair for an incomplete atrioventricular septal defect with dextrocardia and prosthetic valve replacements for right and left atrioventricular valve regurgitation, presented as an outpatient. Her medications included tolvaptan 15 mg and warfarin 1.25 mg. She had a slight fever and Osler nodes at her fingers. Blood culture bottles grew methicillin-resistant Staphylococcus epidermidis, and several vegetations were observed on the right atrioventricular mechanical valve with a transoesophageal echocardiogram. She was diagnosed with prosthetic valve endocarditis and treated with antibiotic agents including rifampicin. After a week, she developed systemic oedema and had a marked decrease in prothrombin time-international normalized ratio (PT-INR). Rifampicin was promptly discontinued due to a strong suspicion of a drug-drug interaction. Consequently, both her congestion and the PT-INR stabilized, and she was discharged after 8 weeks of antibiotic treatment. Discussion: The introduction of rifampicin induces CYP family members such as CYP3A4 and CYP2C9. Warfarin is metabolized by CYP2C9 and tolvaptan is also metabolized by CYP3A4, resulting in a notable reduction of their blood levels when co-administered with rifampicin. The clinical challenges arising from interactions between HF drugs and rifampicin can be categorized into two main groups: worsening HF and thrombotic complications. Clinicians should remain vigilant and informed about these potential issues.

Effectiveness of tolvaptan on renal replacement therapy in patients with autosomal dominant polycystic kidney disease: a retrospective cohort study from the TriNetX global collaborative network.

BACKGROUND AND HYPOTHESIS: Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a major genetic contributor to end-stage kidney disease (ESKD). Current evidence on tolvaptan primarily focuses on slowing estimated glomerular filtration rate (eGFR) decline and kidney volume growth. However, direct confirmation of its effectiveness in reducing the need for hemodialysis in ESKD remains limited. METHODS: We included ADPKD patients aged ≥18 years using TriNetx data from Sep 2, 2018, to Sep 3, 2023. Propensity score matching (PSM) ensured baseline comparability (standardized mean difference (SMD) <0.1). Hazard ratios (HRs) with 95% confidence intervals (CIs) evaluated outcomes, and subgroup analyses were performed. RESULTS: After 1:1 PSM, both groups comprised 673 patients. The average age was 45, with generally good health (3-5% diabetes, 2-3% ischemic heart disease). Baseline eGFR averaged ∼55 ml/min/1.732m2. Post-matching, all SMDs were <0.1, indicating successful matching. Tolvaptan users exhibited lower eGFR (51.45 ± 30.09 vs. 57.37 ± 33.65, p < 0.001) and higher risk of stage 4-CKD (HR: 2.436, 95% CI:1.649, 3.599) compared to non-users. However, tolvaptan users showed significantly reduced chances of initiating hemodialysis (HR:0.362, 95%CI:0.176, 0.745), experiencing urinary tract infections (HR:0.581, 95%CI:0.354, 0.956), and all-cause mortality (HR:0.355, 95% CI:0.180, 0.700). Kaplan-Meier curves for hemodialysis initiation indicated higher survival rates among tolvaptan users across age and number of medication refill subgroups. CONCLUSIONS: This real-world study, employing precise matching, reveals tolvaptan's role in reducing hemodialysis initiation risk in ADPKD, despite initial hemodynamic-induced lower eGFR.

Tolvaptan and the role of kidney aquaporin-2 abundance in managing volume overload in patients with CKD.

Objective: This retrospective study evaluated tolvaptan's efficacy, safety, and predictive indicators in managing volume overload in chronic kidney disease (CKD) patients. Methods: CKD patients with volume overload, treated with loop diuretics alone or with tolvaptan at Zhongda Hospital, Southeast University, from 1 March 2022 to 31 December 2023, were included. Patients were divided into loop diuretic (Group C) and loop diuretic combined with tolvaptan (Group T) cohorts. Primary outcomes included volume control, changes in weight, urine output, and laboratory parameters within 1 week post-medication. Adverse events such as hypernatremia and hyperkalemia, etc., were recorded. We further conducted immunohistochemical staining of renal biopsy tissues to investigate the roles of aquaporin-2 (AQP2) in the collecting duct and plasma albumin in predicting the efficacy of tolvaptan. Results: Of 174 CKD patients with volume overload, 108 (67.07%) were male. Group C and Group T each comprised 87 patients. At baseline, no significant differences in urine output and weight were noted. By day 3, Group T exhibited a greater increase in urine output (P < .001) and weight reduction (P < .001). At day 7, Group T maintained more significant diuretic effects (P < .001). More Group C patients required ultrafiltration therapy (P = .040). Adverse event rates did not significantly differ. Notably, AQP2 expression in the collecting duct may predict tolvaptan responsiveness, while plasma albumin did not affect efficacy. Conclusion: Tolvaptan showed efficacy and safety in managing volume overload in CKD patients. The expression of AQP2 in the collecting duct could predict tolvaptan's efficacy.This study protocol was approved by the Ethics Committee of Zhongda Hospital Affiliated to Southeast University (Approval No. 2023ZDSYLL180-P01, Clinical Trial Registration No. ChiCTR2300075274, Trial Registration Link: https://www.chictr.org.cn/guide.html).

Therapeutic approach to acute crises of hepatic porphyrias.

Acute hepatic porphyria is a genetic disorder affecting enzymes involved in heme biosynthesis. The most common subtype is acute intermittent porphyria, accounting for 80% of cases. Other types include hereditary coproporphyria, variegate porphyria, and delta-aminolevulinic acid dehydratase deficiency. Attacks in acute hepatic porphyria are triggered by the induction of hepatic ALA synthase 1, leading to the accumulation of neurotoxic heme intermediates, delta-aminolevulinic acid, and porphobilinogen. Women experience attacks more frequently than men. Acute porphyria attacks are characterized by severe, diffuse abdominal pain, muscle weakness, autonomic neuropathy (including hypertension, tachycardia, nausea, vomiting, and constipation), and changes in mental status. Early recognition of the disease is crucial as it requires urgent medical attention and treatment. Management includes intravenous opioids, glucose, hemin, and the removal of triggering factors. Preventive treatment options include hormone suppression therapy, off-label prophylactic hemin, Givosiran, and exceptionally liver transplantation.

The Vasopressin Receptor Antagonist Tolvaptan Counteracts Tumor Growth in a Murine Xenograft Model of Small Cell Lung Cancer.

We have previously demonstrated that the vasopressin type 2 receptor (AVPR2) antagonist tolvaptan reduces cell proliferation and invasion and triggers apoptosis in different human cancer cell lines. To study this effect in vivo, a xenograft model of small cell lung cancer was developed in Fox1nu/nu nude mice through the subcutaneous inoculation of H69 cells, which express AVPR2. One group of mice (n = 5) was treated with tolvaptan for 60 days, whereas one group (n = 5) served as the control. A reduced growth was observed in the tolvaptan group in which the mean tumor volume was significantly smaller on day 60 compared to the control group. In the latter group, a significantly lower survival was observed. The analysis of excised tumors revealed that tolvaptan effectively inhibited the cAMP/PKA and PI3K/AKT signaling pathways. The expression of the proliferative marker proliferating cell nuclear antigen (PCNA) was significantly lower in tumors excised from tolvaptan-treated mice, whereas the expression levels of the apoptotic marker caspase-3 were higher than those in control animals. Furthermore, tumor vascularization was significantly lower in the tolvaptan group. Overall, these findings suggest that tolvaptan counteracts tumor progression in vivo and, if confirmed, might indicate a possible role of this molecule as an adjuvant in anticancer strategies.

Prognostic effect of a vasopressin V2 receptor antagonist in acute congestive heart failure patients with hypoperfusion, the wet-cold pattern.

PURPOSE: This study investigated whether the oral vasopressin V2 receptor antagonist tolvaptan has beneficial effects on mortality in real-world congestive heart failure (CHF) patients with hypoperfusion (i.e. the wet-cold pattern), from the viewpoint of cardiorenal syndrome. METHODS: Data on 5511 consecutive CHF patients were extracted from the Tokyo CCU Network data registry. Congestion and hypoperfusion were defined by Nohria-Stevenson clinical profiles at the time of hospitalization. Propensity scores for tolvaptan use were calculated for each patient and used to assemble two matched cohorts of patients receiving tolvaptan or not in the CHF with and without hypoperfusion groups. RESULTS: Of the entire study cohort, 1073 patients (19%) had CHF with hypoperfusion (i.e. the wet-cold pattern). In-hospital mortality was significantly higher for CHF patients with than without hypoperfusion (log-rank, P < 0.001). The rate of tolvaptan use did not differ significantly between CHF patients with and without hypoperfusion (15% vs. 14%, respectively; P = 0.7848). In the propensity-matched CHF with hypoperfusion cohort, there was a significant association between the use of tolvaptan and a reduction in in-hospital mortality (log-rank, P = 0.0052). Conversely, in the matched CHF without hypoperfusion cohort, tolvaptan use was not associated with in-hospital mortality (log-rank, P = 0.4417). CONCLUSION: There was a significant association between the use of tolvaptan and a reduction in in-hospital mortality in CHF patients with, but not without, hypoperfusion. These findings hint at possible individualized therapies for patients with CHF.

Duloxetine-Induced Antidiuresis in Rats with Lithium-Induced Nephrogenic Diabetes Insipidus.

Antidepressants, including duloxetine, are a significant cause of drug-induced hyponatremia, which can disrupt the continuation of medication. Tolvaptan is beneficial for correcting hyponatremia caused by the syndrome of inappropriate antidiuresis, but its impact on duloxetine-induced hyponatremia remains unknown. We used male Sprague-Dawley rats to examine the impact of duloxetine treatment on lithium-induced nephrogenic diabetes insipidus (Li-NDI) and to evaluate whether the results were reversed by co-treatment with tolvaptan. To induce Li-NDI, lithium chloride (40 mmol lithium/kg dry food) was administered for 2 weeks. Duloxetine (50 mg/kg/day) and tolvaptan (10 mg/kg/day) were also administered in food to assess their individual effects over the same period. At the end of each animal experiment, kidneys were harvested to measure levels of cAMP, vasopressin-2 receptor (V2R), cAMP-responsive element binding protein 1 (CREB-1), aquaporin-2 (AQP2), and prostaglandin E2 (PGE2). Water diuresis was induced in the Li-NDI rats, and duloxetine treatment reduced polyuria while increasing urine osmolality. Duloxetine treatment prevented the decrease in total AQP2, AQP2 phosphorylation at serine 256, and CREB-1 phosphorylation in Li-NDI rats. The V2R mRNA level was also reduced in Li-NDI rats and restored by duloxetine treatment. In the subsequent experiment, the decreased water diuresis in Li-NDI rats treated with duloxetine was reversed by co-treatment with tolvaptan. Tolvaptan co-treatment also reversed the changes in AQP2 protein and CREB-1 phosphorylation in the renal cortex and medulla. The decreased cAMP levels in Li-NDI rat kidneys were elevated by duloxetine treatment, and this elevation was reversed by co-treatment with tolvaptan. However, the elevated PGE2 levels in Li-NDI rat kidneys were not affected by either duloxetine alone or tolvaptan co-treatment. In conclusion, antidiuresis was induced by duloxetine in Li-NDI and reversed by tolvaptan co-treatment through alterations in the V2R-cAMP-AQP2 pathway. These findings could underlie the mechanism of duloxetine-induced hyponatremia and suggest the potential usefulness of tolvaptan in treating drug-induced hyponatremia.

Acute Kidney Injury Due to Nephrolithiasis in Autosomal Dominant Polycystic Kidney Disease Treated With Tolvaptan: A Case Report.

A 61-year-old asymptomatic female with autosomal dominant polycystic kidney disease (ADPKD) on tolvaptan therapy was hospitalized for acute kidney injury (AKI). Nephrolithiasis had already been diagnosed; however, the patient had not undergone any interventions. She also presented with hyponatremia possibly caused by overhydration. Because the estimated glomerular filtration rate (eGFR) decline was significantly higher than the predicted rate, we considered a possible case of postrenal AKI and examined computed tomography (CT), which revealed left hydronephrosis with a 9.4-mm ureteric stone at the level of L3/L4. We restricted fluid intake, which resulted in an increase in sodium levels. She was treated with transurethral lithotripsy (TUL) twice, which successfully improved her kidney function. Although the serum sodium levels increase because of aquaresis in almost all patients treated with tolvaptan, our case was unique in that the patient presented with hyponatremia. We should pay more attention to the periodical follow-up of nephrolithiasis in addition to the increase in total kidney volume and decide the appropriate time to treat nephrolithiasis depending on the case. We should also keep in mind that ADPKD patients have a high frequency of nephrolithiasis and, even if asymptomatic, investigate urinary tract obstruction and hydronephrosis in case of AKI.

Development, validation and application of a UPLC-MS/MS method for simultaneous quantification of OPC-61815 and its metabolites tolvaptan, DM-4103 and DM-4107 in human plasma.

OPC-61815 is an intravenous formulation vasopressin antagonist designed to treat heart failure patients, especially who have difficulty in oral intake. Tolvaptan together with DM-4103 and DM-4107 are considered as the major metabolites of OPC-61815 biotransformed in the liver via cytochrome P450 (CYP) 3A. An efficient and robust ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for quantification of OPC-61815 and its three metabolites in human plasma was developed and fully validated. To our best knowledge, it was the first published method that simultaneously quantified all of these four analytes in only one run. Simple and rapid sample preparation procedure and very short UPLC-MS/MS run time (3.5 min) offered OPC-61815 and its metabolites relatively high throughput detection, which was greatly beneficial to further clinical bio-sample analysis. The method showed good linearity and sufficient sensitivity in the range of 2.00-1000 ng/mL with a low limit of quantitation (2.00 ng/mL) for each analyte. For samples with concentrations above 1000 ng/mL, 100-fold dilution with blank plasma before sample preparation was accepted. High precision and accuracy, high selectivity and satisfactory recovery of this method were demonstrated. For all of the four analytes, no significant matrix effect or carry-over was observed. The stability of analytes and internal standards under different conditions were evaluated to ensure they were stable during the whole period of storage, preparation and detection. Also, re-injection reproducibility was investigated. In addition, the conversion test showed that almost no OPC-61815 converted into DM-4103 and DM-4107 during sample processing, while attention should be paid to the concentration difference between OPC-61815 and tolvaptan in bioanalysis. The developed UPLC-MS/MS method was successfully applied to an open, single and multiple dose administration phase I trial for monitoring the pharmacokinetics of OPC-61815. This work provided a promising way for further pharmacokinetic study of OPC-61815.

The role of tolvaptan add-on therapy in patients with acute heart failure: a systematic review and network meta-analysis.

Background: Several conflicting reviews have concluded that the use of loop diuretics is associated with poorer clinical and safety outcomes. Therefore, this study aimed to investigate the efficacy and safety of tolvaptan as an adjunct to conventional diuretic therapy in patients with acute heart failure (AHF). Methods: A comprehensive search was conducted on PubMed, Embase, ProQuest, EBSCO, and Cochrane Library until 24 May 2023 to identify randomized controlled trials that compared the effects of tolvaptan with conventional therapy and placebo in patients with AHF. The quality assessment of the included trials was conducted using the Cochrane risk of bias. A network meta-analysis (NMA) was conducted to examine the dosage effect of tolvaptan. Result: A total of 17 studies with 18 reports, involving 10,039 patients, were selected. The tolvaptan add-on therapy significantly alleviated dyspnea [24 h: RR 1.16 (1.04, 1.29), 48 h: RR 1.18 (1.04, 1.33)], reduced body weight within 48 h [Asian group, MD -0.93 (-1.48, -0.38); non-Asian group, MD -2.76 (-2.88, -2.65)], reduced edema [RR 1.08 (1.02, 1.15)], increased serum sodium [non-Asian group, MD 3.40 (3.02, 3.78)], and resulted in a change in serum creatinine [MD -0.10 (-0.18, -0.01)]. No significant differences were observed in mortality and rehospitalization. The NMA suggested that an intermediate dosage (15 mg/day) might offer the best efficacy in reducing dyspnea within 24 h, reducing edema, increasing serum sodium, and lowering the incidence of worsening renal function (WRF). Conclusion: In conclusion, the meta-analysis showed that tolvaptan contributed to the short-term alleviation of congestive symptoms, elevated sodium levels, and a lower incidence of WRF. However, no significant benefits were observed in long-term symptoms, rehospitalization rates, and mortality. An intermediate dosage of tolvaptan might be considered the optimal choice for various clinical outcomes. Systematic Review Registration: https://www.crd.york.ac.uk/, PROSPERO (CRD42023420288).

QbD green analytical procedure for the quantification of tolvaptan by utilizing stability indicating UHPLC method.

For the first time a new QbD-assisted green stability indicating ultra-high-performance liquid chromatography (UHPLC) method was developed and validated for quantifying Tolvaptan. The method is simple, quick, cost-effective, and stable, and it was used to formulate a quality target product profile (QTPP) with strategically defined critical analytical attributes (CAAs) to meet specific criteria. Chromatographic separation was undertaken using a 10 cm long column of ACE excel super C18 with an interior diameter of 2.1 mm and particle size of 1.7 µm. The analysis was performed under controlled conditions at 25 ℃ with the mobile phase flowing at a rate of 0.2 mL/min and detection occurring at 220 nm. Injected 3 µL of standard by using an isocratic mobile phase system consisting of acetonitrile and water in a 95:5 v/v ratio. The diluents, prepared by mixing acetonitrile with water at a 90:10 volumetric ratio, were utilized. The analyte's retention time was determined to be 1.63 min. The developed method provided reliable results with accuracy exceeding 99% and a correlation coefficient exceeding 0.999 ranged between 10 and 150 µg/mL across the range for LOQ-150% levels. Notably, during forced degradation testing, Tolvaptan exhibited susceptibility to acidic hydrolysis. The method effectively separated degradation products during stress testing, demonstrating its stability-indicating status. Environmental sustainability assessment of the developed method was conducted through the investigation of various indicators of Complex GAPI, Analytical Eco scale and Analytical GREEness and it was concluded the optimized method aligns with environmentally friendly practices.

Structural basis of tolvaptan binding to the vasopressin V2 receptor.

The vasopressin V2 receptor (V2R) is a validated therapeutic target for autosomal dominant polycystic kidney disease (ADPKD), with tolvaptan being the first FDA-approved antagonist. Herein, we used Gaussian accelerated molecular dynamics simulations to investigate the spontaneous binding of tolvaptan to both active and inactive V2R conformations at the atomic-level. Overall, the binding process consists of two stages. Tolvaptan binds initially to extracellular loops 2 and 3 (ECL2/3) before overcoming an energy barrier to enter the pocket. Our simulations result highlighted key residues (e.g., R181, Y205, F287, F178) involved in this process, which were experimentally confirmed by site-directed mutagenesis. This work provides structural insights into tolvaptan-V2R interactions, potentially aiding the design of novel antagonists for V2R and other G protein-coupled receptors.

Clinical efficacy of tolvaptan in acute decompensated heart failure patients with severe aortic stenosis and atrial fibrillation: a sub-analysis from the LOHAS registry.

BACKGROUND: Severe aortic valve stenosis (AS) and atrial fibrillation (AF) are risk factors of hemodynamic instability in heart failure (HF) management due to low cardiac output, respectively. Therefore, the treatment of HF due to severe AS complicated with AF is anticipated to be difficult. Tolvaptan, a vasopressin V2 receptor inhibitor, is effective in controlling acute decompensated heart failure (ADHF) with hemodynamic stability. However, its clinical efficacy against ADHF caused by AS with AF remains to be determined. METHODS: Clinical information (from September 2014 to December 2017) of 59 patients diagnosed with ADHF due to severe AS (20 patients with AF; 39 patients with sinus rhythm [SR]) was obtained from the LOHAS registry. The registry collected data from seven hospitals and assessed the short-term effects of tolvaptan in patients hospitalized for ADHF with severe AS. We attempted to identify clinical differences from baseline up to 4 days, comparing patients with AF (AF group) versus those with SR (SR group). RESULTS: There were no significant differences between the groups in age (83.7 ± 4.5 vs. 85.8 ± 6.9 years, respectively; p = 0.11) and aortic valve area (0.60 [0.46-0.73] vs. 0.56 [0.37-0.70] cm2, respectively; p = 0.50). However, left atrial volume was larger (104 [85-126] vs. 87 [64-103] mL, respectively; p < 0.01), whereas stroke volume was lower (51.6 ± 14.8 vs. 59.0 ± 18.7 mL, respectively; p = 0.08) in the AF group versus the SR group. Body weight decreased daily from baseline up to day 4 in both groups (from 55.4 to 53.2 kg [p < 0.01] and from 53.5 to 51.0 kg [p < 0.01], respectively) without change in heart rate. Notably, the systolic blood pressure decreased slightly in the AF group after 2 days of treatment with tolvaptan. CONCLUSIONS: Short-term treatment with tolvaptan improved HF in patients hospitalized for severe AS, regardless of the presence of AF or SR. After achieving sufficient diuresis, a slight decrease in blood pressure was observed in the AF group, suggesting an appropriate timeframe for safe and effective use of tolvaptan.

Case report: Secondary failure to tolvaptan in a patient with SCLC and paraneoplastic SIADH.

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is frequent in lung cancer patients. Here, we report a case with persistent hyponatremia, which suggested malignant SIADH and facilitated an early diagnosis of small cell lung cancer (SCLC). A combined radio-chemotherapy led to a partial remission and resolution of SIADH. An early relapse was indicated by reoccurring severe hyponatremia and increased copeptin levels, which were used as surrogate markers for the antidiuretic hormone (ADH). As palliative immunochemotherapy, together with fluid restriction and solute substitution, were unable to control hyponatremia, treatment with the ADH V2-receptor antagonist tolvaptan was initiated. Over time, the dose of tolvaptan needed to be increased, paralleled by a well-documented exponential increase of copeptin levels. In summary and conclusion, this is a rare case of a secondary failure to tolvaptan with unique documentary evidence of increasing copeptin levels. This observation supports the hypothesis that exceedingly high ADH levels may lead to competitive displacement of tolvaptan from the V2 receptor.

Prospective Study on Individualized Dose Adjustment of Tolvaptan Based on Urinary Osmolality in Patients With ADPKD.

Introduction: Tolvaptan has been shown to reduce renal volume and delay disease progression in autosomal-dominant polycystic kidney disease (ADPKD). However, no biomarkers are currently available to guide dose adjustment. We aimed to explore the possibility of individualized tolvaptan dose adjustments based on cut-off values for urinary osmolality (OsmU). Methods: This prospective cohort study included patients with ADPKD, with rapid disease progression. Tolvaptan treatment was initiated at a dose of 45/15 mg and increased based on OsmU, with a limit set at 200 mOsm/kg. Primary renal events (25% decrease in estimated glomerular filtration rate [eGFR] during treatment), within-patient eGFR slope, and side effects were monitored during the 3-year follow-up. Results: Forty patients participated in the study. OsmU remained below 200 mOsm/kg throughout the study period, and most patients required the minimum tolvaptan dose (mean dose, 64 [±10] mg), with a low discontinuation rate (5%). The mean annual decline in eGFR was -3.05 (±2.41) ml/min per 1.73 m2 during tolvaptan treatment, compared to the period preceding treatment, corresponding to a reduction in eGFR decline of more than 50%. Primary renal events occurred in 20% of patients (mean time to onset, 31 months; 95% confidence interval [CI] = 28-34). Conclusion: Individualized tolvaptan dose adjustment based on OsmU in patients with ADPKD and rapid disease progression provided benefits in terms of reducing eGFR decline, compared with reference studies, and displayed lower dropout rates and fewer side effects. Further studies are required to confirm optimal strategies for the use of OsmU for tolvaptan dose adjustment in patients with ADPKD.

Measured and Estimated Glomerular Filtration Rate to Evaluate Rapid Progression and Changes over Time in Autosomal Polycystic Kidney Disease: Potential Impact on Therapeutic Decision-Making.

Autosomal polycystic kidney disease (ADPKD) is the most common genetic form of kidney failure, reflecting unmet needs in management. Prescription of the only approved treatment (tolvaptan) is limited to persons with rapidly progressing ADPKD. Rapid progression may be diagnosed by assessing glomerular filtration rate (GFR) decline, usually estimated (eGFR) from equations based on serum creatinine (eGFRcr) or cystatin-C (eGFRcys). We have assessed the concordance between eGFR decline and identification of rapid progression (rapid eGFR loss), and measured GFR (mGFR) declines (rapid mGFR loss) using iohexol clearance in 140 adults with ADPKD with ≥3 mGFR and eGFRcr assessments, of which 97 also had eGFRcys assessments. The agreement between mGFR and eGFR decline was poor: mean concordance correlation coefficients (CCCs) between the method declines were low (0.661, range 0.628 to 0.713), and Bland and Altman limits of agreement between eGFR and mGFR declines were wide. CCC was lower for eGFRcys. From a practical point of view, creatinine-based formulas failed to detect rapid mGFR loss (-3 mL/min/y or faster) in around 37% of the cases. Moreover, formulas falsely indicated around 40% of the cases with moderate or stable decline as rapid progressors. The reliability of formulas in detecting real mGFR decline was lower in the non-rapid-progressors group with respect to that in rapid-progressor patients. The performance of eGFRcys and eGFRcr-cys equations was even worse. In conclusion, eGFR decline may misrepresent mGFR decline in ADPKD in a significant percentage of patients, potentially misclassifying them as progressors or non-progressors and impacting decisions of initiation of tolvaptan therapy.

An Electronic Health Record-Integrated Application for Standardizing Care and Monitoring Patients With Autosomal Dominant Polycystic Kidney Disease Enrolled in a Tolvaptan Clinic: Design and Implementation Study.

Background: Tolvaptan is the only US Food and Drug Administration-approved drug to slow the progression of autosomal dominant polycystic kidney disease (ADPKD), but it requires strict clinical monitoring due to potential serious adverse events. Objective: We aimed to share our experience in developing and implementing an electronic health record (EHR)-based application to monitor patients with ADPKD who were initiated on tolvaptan. Methods: The application was developed in collaboration with clinical informatics professionals based on our clinical protocol with frequent laboratory test monitoring to detect early drug-related toxicity. The application streamlined the clinical workflow and enabled our nursing team to take appropriate actions in real time to prevent drug-related serious adverse events. We retrospectively analyzed the characteristics of the enrolled patients. Results: As of September 2022, a total of 214 patients were enrolled in the tolvaptan program across all Mayo Clinic sites. Of these, 126 were enrolled in the Tolvaptan Monitoring Registry application and 88 in the Past Tolvaptan Patients application. The mean age at enrollment was 43.1 (SD 9.9) years. A total of 20 (9.3%) patients developed liver toxicity, but only 5 (2.3%) had to discontinue the drug. The 2 EHR-based applications allowed consolidation of all necessary patient information and real-time data management at the individual or population level. This approach facilitated efficient staff workflow, monitoring of drug-related adverse events, and timely prescription renewal. Conclusions: Our study highlights the feasibility of integrating digital applications into the EHR workflow to facilitate efficient and safe care delivery for patients enrolled in a tolvaptan program. This workflow needs further validation but could be extended to other health care systems managing chronic diseases requiring drug monitoring.

Juxtaglomerular apparatus-mediated homeostatic mechanisms: therapeutic implication for chronic kidney disease.

INTRODUCTION: Juxtaglomerular apparatus (JGA)-mediated homeostatic mechanism links to how sodium-glucose cotransporter 2 inhibitors (SGLT2is) slow progression of chronic kidney disease (CKD) and may link to how tolvaptan slows renal function decline in autosomal dominant polycystic kidney disease (ADPKD). AREA COVERED: JGA-mediated homeostatic mechanism has been hypothesized based on investigations of tubuloglomerular feedback and renin-angiotensin system. We reviewed clinical trials of SGLT2is and tolvaptan to assess the relationship between this mechanism and these drugs. EXPERT OPINION: When sodium load to macula densa (MD) increases, MD increases adenosine production, constricting afferent arteriole (Af-art) and protecting glomeruli. Concurrently, MD signaling suppresses renin secretion, increases urinary sodium excretion, and counterbalances reduced sodium filtration. However, when there is marked increase in sodium load per-nephron, as in advanced CKD, MD adenosine production increases, relaxing Af-art and maintaining sodium homeostasis at the expense of glomeruli. The beneficial effects of tolvaptan on renal function in ADPKD may also depend on the JGA-mediated homeostatic mechanisms since tolvaptan inhibits sodium reabsorption in the thick ascending limb.The JGA-mediated homeostatic mechanism regulates Af-arts, constricting to relaxing according to homeostatic needs. Understanding this mechanism may contribute to the development of pharmacotherapeutic compounds and better care for patients with CKD.