Question

Which of the following prostaglandin is used in the treatment of pulmonary arterial hypertension?

• A. Thromboxane A2
• B. Prostacyclin
• C. Misoprostol
• D. Fasudil

Hint:

Prostacyclin (\(\text{PGI}_2\)) cycle: Endothelial-derived \(\rightarrow\) Vasodilation \(\rightarrow\) Inhibits platelet aggregation. Think of it as the body's natural protectant against high blood pressure and clotting.

Answer 1

The Correct Option is B

Concept: Pulmonary arterial hypertension (PAH) is characterized by chronic, pathological vasoconstriction and remodeling of the pulmonary vasculature, leading to high vascular resistance. Eicosanoids play a critical role in controlling vascular tone. Vasodilatory prostaglandins are utilized therapeutically to lower pulmonary arterial pressure.

Step 1: Analyze the pharmacological role of Prostacyclin (PGI2) Prostacyclin (\(\text{PGI}_2\)) is naturally produced by vascular endothelial cells. It binds specifically to IP receptors on vascular smooth muscle cells, triggering an increase in intracellular cyclic adenosine monophosphate (cAMP). This cascade leads to profound vasodilation of the pulmonary vascular bed and exerts anti-proliferative effects on smooth muscle tissue, preventing vascular remodeling. Synthetic analogues of prostacyclin (such as Epoprostenol, Treprostinil, and Iloprost) are fundamental line treatments for managing severe PAH.

Step 2: Evaluate the alternatives
• Thromboxane A2 (\(\text{TXA}_2\)): Produced primarily by platelets, it is a powerful vasoconstrictor and platelet aggregator. It would worsen pulmonary hypertension rather than treat it.
• Misoprostol: A synthetic prostaglandin \(\text{E}_1\) (\(\text{PGE}_1\)) analogue. It is predominantly used for prevention of NSAID-induced gastric ulcers and for obstetric indications, not for target pulmonary vasodilation.
• Fasudil: Although it is used to treat vascular conditions, it functions as a Rho-kinase inhibitor, not a prostaglandin compound. Therefore, Prostacyclin is the correct prostaglandin molecule utilized for this indication.