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Antihypertensive Drugs

59-291 Section 3, Lecture 1. Antihypertensive Drugs. 50 million people in the United States suffer from high blood pressure (hypertension) Hypertension: Systolic BP >= 140 mmHg, Diastolic BP >= 90 mmHg Untreated hypertension: Damages blood vessels Accelerates atherosclerosis

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Antihypertensive Drugs

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  1. 59-291 Section 3, Lecture 1 Antihypertensive Drugs • 50 million people in the United States suffer from high blood pressure (hypertension) • Hypertension: Systolic BP >= 140 mmHg, Diastolic BP >= 90 mmHg • Untreated hypertension: • Damages blood vessels • Accelerates atherosclerosis • Left ventricular hypertrophy • Ischemic heart disease, stroke, heart failure and kidney failure

  2. Hypertension • Primary; 95%: No underlying disease • risk factors • Obesity, Lack of exercise, Metabolic syndrome; (abdominal obesity, hyperlipidemia, insulin resistance), excessive dietary salt intake, excessive alcohol intake • Secondary; 5% caused by consequence of other disease; chronic kidney disease, pheochromocytoma, hyperaldosteronism

  3. Classification of BP was presented in the Seventh Report of the Joint National Committee on the Prevention, Detection, and Treatment of High Blood Pressure; 2003 Table 10-1. Classification of Blood Pressure for Adults and Follow-up Recommendations

  4. Blood Pressure Regulation • BP is influenced by cardiac output and peripheral vascular resistance and regulated by sympathetic nervous system (short term regulation) and kidneys (long term control) • BP=CO x PVR • Cardiac output: • CO = Stroke volume x heart rate • Increased by activation of b1 receptors • Kidneys regulate blood volume and CO • PVR: resistance to blood flow through arteriols; • Cross sectional area depends on arteriolar smooth muscle tone • Activation of a1 receptors causes vasoconstriction

  5. Blood Pressure Regulation: BP= CO x PVR

  6. CO= Stroke Volume x Heart Rate  By sypm. Stimulation of 1 receptors in the heart ;kidneys also play a role in CO by their role in regulating blood volume which determine cardiac filling pressure and stroke volume

  7. PVR (Peripheral Vascular resistance)- resistance to blood flow through the arterioles Symp. Stimulation of -receptors- contraction of vascular smooth muscle leading to elevated BP. In addition, the release of angiotensin II and vasopressin also induce vasoconstriction Note: Symp. Regulation of BP Short term via baroreflex BP due to altered posture/physical activity Symp.  via CO  and PVR 

  8. The Long term regulation of BP by the kidneys. -via regulation of plasma V and renin-angiotensin-aldosterone system Normotensive-BP excretion of Na+  H2O > BP normal Hypertensive-BP regulation is defective PVR is but it is unknown whether this is the cause or effect of hypertension. Sites of pharmaceutical intervention 4- major categories of drugs: 1- diuretics 2-sympatholytics 3- ACE inhibitors 4- vasodialtors

  9. vasodilators a-antagonists b-antagonists Angiotensin II receptor antagonists b-antagonists CNS-directed sympatholytics b-antagonists ACE inhibitors Angiotensin II receptor antagonists diuretics

  10. Practice Questions • Explain how stimulation of b1 receptors increases BP. • Increase heart rate • increase CO • increase BP

  11. Explain “Prehypertension” condition and the follow up recommendation for this condition. • SBP 120-139 or • DBP 80-90 • Check again in 1 year

  12. What type of drugs decrease PVR? • Vasodilators • Angiotensin II receptor antagonists • a blockers

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