Hypertension – Mechanisms & Medications

The 5 meds we learned for antihypertension

What are antihypertensives?

Medications whose purpose is to lower blood pressure

What happens when calcium enters vascular smooth muscle?

• calcium enters smooth muscle

• muscle contracts

• vasoconstriction

• increased SVR (afterload)

• increased BP

(Ca channel open → vessel tightens → ↑ SVR → ↑ BP)

How do calcium channel blockers (nifedipine) lower blood pressure?

• block calcium entry into vascular smooth muscle

• prevent contraction

• cause vasodilation

• decrease SVR (afterload)

• decrease BP

acts mainly on arterioles

What are the adverse effects of calcium channel blockers (nifedipine)?

adverse effects: tachycardia, dizziness

What are the effects of angiotensin II?

• vasoconstriction = ↑ SVR , ↑ BP

• stimulates aldosterone release (from the adrenal cortex)

• aldosterone → Na⁺ & water reabsorption

• increased BV = ↑ preload , ↑ BP

How to ACE inhibitors (enalapril) lower blood pressure?

• block conversion of angiotensin I → angiotensin II

• ↓ vasoconstriction → ↓ SVR (afterload)

• ↓ aldosterone = ↑ diuresis

• ↓ blood volume = ↓ preload

• ↓ BP

What are the adverse effects of ACE inhibitors (enalapril)?

adverse effects: dry cough, dizziness, hyperkalemia(increased potassium in the blood)

What happens when beta-1 receptors are stimulated?

• Located in the heart

• ↑ heart rate

• ↑ force of contraction

• ↑ cardiac output

• ↑ blood pressure

How do beta blockers (metoprolol) lower blood pressure?

• Block beta-1 receptors in the heart

• ↓ heart rate

• ↓ contractility

• ↓ cardiac output

• ↓ BP

• suppress activity of renin

What are the adverse effects of beta blockers (metoprolol)?

adverse effects: bradycardia, orthostatic hypotension, dizziness, rebound of hypertension if stops taking meds abruptly

What happens when alpha-1 receptors are stimulated?

• Located on blood vessels

• Causes vasoconstriction

• ↑ SVR (afterload)

• ↑ blood pressure

How do alpha-1 blockers (doxazosin) lower blood pressure?

• Block alpha-1 receptors

• Prevent vasoconstriction

• Cause arterial & venous dilation

• ↓ SVR (afterload)

• ↓ venous return (preload)

• ↓ BP

What are the adverse effects of alpha-1 blockers (doxazosin)?

adverse effects: orthostatic hypotension (common), dizziness

How does ASA (antiplatelet medication) (aspirin) help prevent heart attack, stroke, cardiovascular disease and blood clots?

• Antiplatelet medication

• Inhibits platelet aggregation

• Prevents clot formation

• Reduces risk of MI and stroke

Why is ASA (antiplatelet medication) used in patients with hypertension or heart disease?

• Hypertension damages blood vessels

• Damaged vessels increase clot risk

• ASA prevents platelet clumping

• Reduces risk of cardiovascular events

• Inhibits COx-1in platelets (preventing platelet

What is the adverse effect of ASA (antiplatelet medication)?