This document discusses drugs that inhibit the renin-angiotensin system for treating hypertension and other conditions. It describes how ACE inhibitors work by inhibiting the angiotensin converting enzyme and decreasing angiotensin II formation, while also increasing bradykinin levels. Angiotensin receptor blockers competitively block the angiotensin II receptor. Both classes lower blood pressure by vasodilation and reduced sodium retention. They are used to treat hypertension, heart failure, diabetic nephropathy, and myocardial infarction. Adverse effects include hypotension, hyperkalemia, and cough with ACE inhibitors.