Drug NOT used in pulmonary hypeension aEUR'
alpha blockers Pulmonary hypeension General management Diuretic therapy may be useful as it relieves pulmonary edema. Anticoagulant therapy is advocated for all patients. Specific management Calcium channel blockers Patients who have substantial reductions in pulmonary aerial pressure in response to sho acting vasodilators at the time of cardiac catheterization should he initially treated with calcium channel blockers. Endothelin receptor antagonist Bostenan is a non-selective endothelium receptor antagonist, is an approved t/t ,for patients who are NYHA .functional classes III and IV. Phosphodiesterase-5 inhibitors Slidenafil is used for patients who are NYHA functional classes II and Prostacyclins Iloprost is a prostacyclin analogue used in PAH patients who are NYHA functional classes III and IV. Pulmonary circulation is unique in that it accommodates a blood flow that is almost equal to that of all the other organs of body but still maintains low pressure. The factors responsible for low pressure in pulmonary circulation (even with large volume of blood) are:- - Larger diameter of pulmonary vessels due to thin wall of pulmonary aery and aerioles. - Greater compliance (distensibility) of pulmonary vessels. numoral factors responsible for maintaining pulmonary circulation:? Normally NO causes vosodilation and proliferation of smooth muscles by r in the conc. of cGMP --) this increases the diameter of pulmonary vessels. causes vosodilation and decreased proliferation of smooth muscles by increasing the conc. of cAMPincrease in the diameter of pulmonary vessels. Prostaglandin also decreases coagulation. Endothelin causes vasoconstriction and increase smooth muscle proliferation si lumen of pulmonary vessels. - Normally the vasodilators and antiprolifeave effects of NO and PGI7 dominate In Pulmonary hypeension There is l production of NO (and cGMP) and PGI2 (and cAMP), t vasoconstriction and proliferation of smooth muscles, st lumen of pulmonary vessel. Decreased production of PGI2 also causes increased coagulation. There is T production of endothelin, /vasoconstriction and smooth muscle proliferation, .1 lumen. Drug therapy in puhnonan, hypeension is targetted at these growth factor pathways which are involved in the pathogenesis of pulmonary hypeension: Endothelium receptor antagonist Bostenan is an endothelin receptor antagonist. It prevents endothelin mediated contraction of vessels. Phosphodiesterase-5 inhibitors Nitric oxide mediates its action through increasing cGMP concentration. Increased cGMP relaxes the vessels. cGMP is degraded by an enzyme phosphodiesterase-5 (PDE-5). - Slidenafanil is a phosphodiesterase 5 inhibitor. It reduces the degradation of cGMP, thus causing vascular relaxation and reducing pulmonary hypeension. Prostacyclins In pulmonary hypeension, the level of prostacycline is reduced. This causes pulmonary constriction as prostacyclin causes dilatation of pulmonary vessels.
Calcium channel blocker
Endothelin receptor antagonist
Alpha blocker
Prostacyclin