Efficacy and safety of inhaled nitrite in addition to sildenafil in thalassemia patients with pulmonary hypertension: A 12-week randomized, double-blind placebo-controlled clinical trial

Effectiveness and safety of the use of sodium nitrite in patients with hypertension and pulmonary hypertension: a scoping review

Evidence suggests that sodium nitrite may be effective in the treatment of hypertension and pulmonary hypertension. However, its use remains debated due to safety concerns. In response, a scoping review was conducted to map current knowledge on the efficacy and safety of sodium nitrite in patients with hypertension or pulmonary hypertension, addressing the question: What evidence supports the effectiveness and safety of using sodium nitrite in these patients? The databases MEDLINE (PubMed), EMBASE, Scopus, Web of Science, and LILACS were searched for clinical studies on hypertensive patients at any disease stage without restrictions on age, sex, ethnicity, publication date, or status. The primary outcomes analyzed were the efficacy and safety of sodium nitrite. A total of nine articles were included, eight from databases and one from gray literature. Sample sizes ranged from 5 to 36 patients, with sodium nitrite doses between 240 µg/kg/h and 325 mg. Five studies showed positive results for treating essential hypertension. Regarding safety, only one study raised concerns about adverse effects, probably due to the high dose that was used. In pulmonary hypertension patients classified as groups 2, 3, and 5, four studies suggested sodium nitrite was effective and safe, but it was ineffective in group 1. The studies included several significant limitations that should be considered. As such, the current evidence is insufficient to definitively confirm the efficacy and safety of sodium nitrite in hypertensive patients. Further research with larger sample sizes is necessary to obtain more conclusive results.

Extracellular vesicles modulate endothelial nitric oxide production in patients with β‑thalassaemia/HbE

Thrombosis is a significant complication in patients with β-thalassaemia/haemoglobin E (HbE), particularly in splenectomised patients. The endothelium is a key regulator of vascular haemostasis and homeostasis, through the secretion of various regulatory molecules. Nitric oxide (NO), produced by endothelial cells (ECs), regulates vascular functions by acting as a potent vasodilator and an inhibitor of platelet activation. Decreased NO bioavailability, a marker of vascular dysfunction, could be a contributing factor leading to thrombosis. Microparticles or medium extracellular vesicles (mEVs) are associated with thrombosis and vasculopathy in various diseases. Furthermore, elevated levels of mEVs have been observed in splenectomised patients with β-thalassaemia/HbE and could induce the expression of coagulation proteins, inflammatory cytokines and adhesion molecules in ECs. However, the effects of mEVs on NO regulation by ECs is currently unclear. In the present study, mEVs obtained from splenectomised patients with β-thalassaemia/HbE had significantly decreased NO production in human pulmonary artery ECs without affecting endothelial nitric oxide synthase expression or phosphorylation. Decreased NO production was attributed to increased haemoglobin levels in mEVs from splenectomised patients, leading to enhanced NO scavenging. These findings highlight a mechanism whereby haemoglobin-carrying mEVs directly scavenge NO, contributing to vascular dysfunction in β-thalassaemia/HbE disease.

Randomized Clinical and Biochemical Study Comparing the Effect of L-arginine and Sildenafil in Beta Thalassemia Major Children With High Tricuspid Regurgitant Jet Velocity

Background:

Pulmonary hypertension (PHT) is common in β-thalassemia patients due to hemolysis, iron overload and diminished nitric oxide (NO) levels. Biochemical markers can help to understand the pathophysiology and to introduce new therapies for this condition.

Aim:

This study aimed to evaluate the effectiveness of L-arginine and sildenafil in thalassemia children with PHT at both clinical and biochemical levels.

Methods and Results:

In a randomized controlled study, 60 β-thalassemia major children with PHT were divided into 3 equal groups; Control group (Conventional thalassemia and PHT management), L-arginine group (Conventional + Oral L-arginine 0.1 mg.kg−1 daily), and sildenafil group (Conventional + Oral sildenafil 0.25 mg.kg−1 two times a day) for 60 days. Tricuspid Regurgitant Jet Velocity (TRJV) with Doppler echocardiography along with serum levels of NO, asymmetric dimethylarginine (ADMA), interleukin 1-beta (IL-1β), E-selectin, and visfatin were followed-up at baseline, 30, and 60 days after treatment. Both drugs reduced the TRJV significantly. NO was significantly higher in both L-arginine and sildenafil groups after 60 days compared to baseline, while visfatin levels were lower. Only L-arginine reduced ADMA levels compared to baseline, while sildenafil did not. E-selectin and IL-1β levels did not change remarkably by both drugs. NO and TRJV showed significant negative correlations in both treatment groups.

Conclusion:

L-arginine and sildenafil could clinically ameliorate chronic PHT whereas, L-arginine showed superiority to sildenafil on some biochemical markers.