Reply to the Letter to the Editor: "Risk Trajectory and Right Ventricular Adaptation in Selexipag- Based Triple...

Endothelins (ETs) are potent vasoactive peptides critical in the human body's various physiological and pathological processes. One of the most promising therapeutic strategies for treating pulmonary arterial hypertension (PAH) involves counteracting the effects of these endothelins using a class of drugs known as endothelin receptor antagonists.
ETs are synthesized through a complex sequence of enzymatic steps, primarily involving an enzyme referred to as endothelin-converting enzyme...

Receptor tyrosine kinase inhibitors (TKIs) and calcium channel blockers (CCBs) are two critical categories of drugs employed in the treatment of pulmonary artery hypertension (PAH). PAH is a disease that causes high blood pressure in the pulmonary arteries, resulting in chest pain, fatigue, and shortness of breath.
TKIs, such as imatinib (Gleevec), are particularly effective in tackling the growth and mitogenic factors that become upregulated in PAH patients. These factors contribute to the...

Prostacyclin receptor agonists are a class of therapeutic agents integral to managing pulmonary arterial hypertension (PAH). These drugs operate by mimicking the action of prostaglandin I2, or PGI2, a naturally occurring compound in the body.
These agonists bind to the IPR receptor situated on the plasma membrane of the pulmonary artery smooth muscle cells. This binding triggers a cascade of reactions known as the GS-AC-cAMP-PKA pathway. This pathway results in the relaxation of smooth muscle...

Phosphodiesterase 5 (PDE5) inhibitors are potent enzymes that function to hydrolyze cyclic nucleotides to their corresponding 5' monophosphates. Their unique biochemical properties have been applied in treating Pulmonary Arterial Hypertension (PAH).
Among the PDE5 inhibitors, sildenafil (Revatio) stands out as a competitive and selective inhibitor. It operates by elevating cellular levels of cGMP and augmenting signaling through the cGMP-PKG pathway, promoting vasodilation. Upon oral...

PK–PD modeling has significantly influenced FDA regulatory decisions, particularly drug approval, dosage optimization, and labeling. These models integrate pharmacokinetics (PK) and pharmacodynamics (PD) to predict drug behavior and effects, aiding in optimizing dosing regimens and enhancing the probability of clinical trial success.One notable example is Nesiritide (Natrecor®), a recombinant human brain natriuretic peptide for treating acute decompensated congestive heart failure...

Aortic regurgitation (AR) is when the aortic valve does not close or seal properly, leading to backward blood circulation from the aorta into the left ventricle during diastole. Common causes of AR include rheumatic heart disease, congenital valve defects, and aortic root dilation. Managing AR requires a multifaceted approach to alleviate symptoms, preserve left ventricular function, and address the underlying cause of the regurgitation. Patients with symptomatic AR or significant left...