This document focuses on drugs affecting circulation with an emphasis on high blood pressure (hypertension). It outlines the different types of hypertension, including primary and secondary hypertension, and describes various stages of the disease. The document then explores several drug classes used to treat hypertension, including ACE inhibitors, angiotensin II receptor blockers (ARBs), calcium channel blockers, beta blockers, diuretics, and others. Finally, it touches on drugs used in treating shock and clotting mechanisms. The document also provides specific drug examples within each class.