Hyponatremia, Heart Failure, and the Role of Tolvaptan

Clinically approved representative small-molecule drugs for cardiopathy therapy

The application of therapeutic agents for cardiopathy has brought about significant advancements in the treatment of cardiovascular diseases. The intervention of small-molecule drugs has led to substantial reductions in morbidity and mortality rates, along with decreased utilization of healthcare resources. However, current treatment modalities do not exhibit uniform efficacy across all patients, and the emergence of drug resistance poses a significant challenge to further therapeutic efforts. Additionally, chronic administration of these drugs can result in toxicities, adding complexity to long-term management. This review focuses on the application of clinically approved small-molecule drugs for the treatment of cardiopathy, covering major classes such as angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, calcium channel blockers, β-blockers, and sodium-glucose co-transporter 2 inhibitors. The review provides an in-depth analysis of their synthetic routes, mechanisms of action, and roles in cardiopathy treatment. It also offers perspectives on future directions in the development of next-generation cardioprotective agents, aiming to optimize therapeutic strategies for cardiovascular disease management.

Development of highly selective and sensitive molecularly imprinted polymer-based electrochemical sensors for tolvaptan assay in tablets and serum

In this research, two different molecularly imprinted polymer (MIP)-based electrochemical sensors were proposed for the determination of tolvaptan (TOL). Photopolymerization (PP) and thermal polymerization (TP) techniques were developed for the determination of TOL. The advantages of MIP were used to design an electrochemical sensor for selective and sensitive determination of TOL. TOL was determined on a glassy carbon electrode (GCE) using differential pulse voltammetry (DPV) for both techniques. Some important parameters affecting the sensor efficiency, such as template/monomer ratio, PP and TP time, drop volume, removal solutions, removal and rebinding time, etc., were optimized. The surface characterization of the proposed MIP-based electrochemical sensors was carried out with electrochemical characterization by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) methods. It was extended with the scanning electron microscopy (SEM) technique. Under optimal conditions, the developed sensors showed good linearity between 1.0 × 10-11 M and 1.0 × 10-10 M, and 2.5 × 10-11 M and 2.5 × 10-10 M for PP and TP, respectively. Low detection limits (2.89 × 10-12 M (PP) and 1.88 × 10-13 M (TP)) were also obtained for TOL determination. The applicability of the proposed sensor was evaluated using tablet and commercial human serum samples. Interference and imprinting factor studies verified the selectivity and specificity of the proposed sensors, and the efficiency of the sensors was verified using an unprinted polymer for comparison at each step.

Effects of tolvaptan on congestive heart failure complicated with chylothorax in a neonate

Tolvaptan is an oral vasopressin type 2 receptor antagonist that can be used for heart failure patients with hyponatremia or symptomatic congestion. Although the effects of tolvaptan in adults have been well documented, only limited information is available in children. The case of a neonate with congestive heart failure complicated with chylothorax after palliative surgery for transposition of the great arteries treated with tolvaptan is reported. Slow up-titration to 0.1 mg/kg successfully increased urine output and improved refractory congestive heart failure without hypernatremia. Subsequently, bodyweight and chylothorax decreased gradually. Moreover, the use of tolvaptan reduced the dosage of furosemide. Tolvaptan could be an alternative drug for neonates with congestive heart failure. Further large studies are needed to confirm the efficacy and identify the appropriate dose of tolvaptan in neonates.

Short term efficacy and safety of low dose tolvaptan in patients with acute decompensated heart failure with hyponatremia: a prospective observational pilot study from a single center in South India

Background:

In acute decompensated heart failure (ADHF), diuretic use, the mainstay therapy for congestion, is associated with electrolyte abnormalities and worsening renal function. Vasopressin mediates fluid retention in heart failure. In contrast to diuretics, the vasopressin antagonist tolvaptan may increase net volume loss in heart failure without adversely affecting electrolytes and renal function. Hyponatremia (serum sodium concentration, <135 mEq/L) is a predictor of death among patients with heart failure.

Objective:

We prospectively observed the short term efficacy and safety of low dose (15 mg) tolvaptan in admitted patients with hyponatremia and ADHF in Indian population.

Methodology:

A total of 40 patients with ADHF along with hyponatremia (<125 mEq/L) on standard therapy were treated with 15 mg of tolvaptan at a single oral dose for 7 days.

Results:

Serum sodium concentrations increased significantly after treatment with tolvaptan from baseline (P < 0.02). There was a significant improvement in symptoms and New York Heart Association (NYHA) class after starting tolvaptan (P ≤ 0.05). Total diuretic dose and mean body weight was reduced non-significantly at 7^th day from the baseline. Side-effects associated with tolvaptan included increased thirst, dry mouth and increased urination. Few patients had worsening renal function. However, several patients developed hypernatremia.

Conclusion:

In this small observational study, tolvaptan initiation in patients with ADHF with hyponatremia in addition to standard therapy may hold promise in improvement in NYHA class and serum sodium. At the same time, we observed that serious adverse events such as renal function deterioration and hypernatremia developed after tolvaptan treatment, which needs to be addressed in future by randomized study with larger sample size.