Pharmacokinetics and pharmacodynamics of single dose of inhaled nebulized sodium nitrite in healthy and hemoglobin E/β-thalassemia subjects

Abstract

© 2019 Elsevier Inc. Inhaled sodium nitrite has been reported to decrease pulmonary artery pressure in hemoglobin E/β-thalassemia (HbE/β-thal) patients with pulmonary hypertension. This study investigated the pharmacokinetics and pharmacodynamics of inhaled nebulized sodium nitrite in 10 healthy subjects and 8 HbE/β-thal patients with high estimated pulmonary artery pressure. Nitrite pharmacokinetics, fraction exhaled nitric oxide (FENO), estimated right ventricular systolic pressure (eRVSP) measured by echocardiography, and platelet activation were determined. Nebulized sodium nitrite at doses used in this study (37.5 and 75 mg for healthy subjects and 15 mg for HbE/β-thal patients) was well tolerated and did not cause changes in methemoglobin levels and systemic blood pressure. Absorption of inhaled nitrite was rapid with the absolute bioavailability of 18%. In whole blood, nitrite exhibited the dose-independent pharmacokinetics with clearance (CL) of 1.5 l/h/kg, volume of distribution (Vd) of 1.3 l/kg and half-life (t1/2) of 0.6 h. CL and Vd of nitrite was higher in red blood cells (RBC) than whole blood and plasma. HbE/β-thal patients had lower nitrite CL and longer t1/2 in RBC than healthy subjects. FENO increased immediately after inhalation. Following nitrite inhalation, eRVSP remained unchanged but platelet activation was suppressed as evidenced by inhibition of adenosine diphosphate (ADP)-induced P-selectin expression and increase in phosphorylated vasodilator-stimulated phosphoprotein (P-VASPSer239) in platelets. There were no changes in markers of oxidative and nitrosative stress after inhalation. Our results support further development of inhaled nebulized sodium nitrite for treatment of pulmonary hypertension in β-thalassemia.