Antihypertensive Drugs

Mechanisms Regulating Blood Pressure

Neural

Hormonal

Vascular

Vascular Remodeling

Neural

Triggered by hypotension & inadequate tissue perfusion

Release of epinephrine & norepinephrine causing

Constriction of blood vessels in the skin, kidney, & GI

The heart rate and the force of the contraction

Hormonal
Renin-Angiotensin-Aldosterone System & Vasopressin

Renin is released in response to

________

________

________

Renin converts angiotensinogen to angiotensin I

Angiontensin-converting enzyme (ACE) produces angiontensin II

Renin-Angiotensin-Aldosterone

http://www.oucom.ohiou.edu/CVPhysiology/BP015.htm

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Angiontensin II

Strongly constricts arterioles

Increases/Decreases? peripheral vascular resistance

Increases BP by direct vasoconstriction, stimulation of the SNS, and stimulation of catecholamine release

Stimulates secretion of Aldosterone

Aldosterone

Kidneys retain sodium and H2O

Retention of sodium and water increases ()

______ _____

______ _____

______ _____

Vasopressin
Antidiuretic Hormone (ADH)

Regulates _______ reabsorption by the kidneys

Released in response to decreased blood volume and blood pressure

Causes

Retention of fluids

vasoconstrction

Vascular

Endothelium damage

Production of vasoconstrictor

Inability to respond to vasodialators

Vascular Remodeling

Endothelial damage

Stimulates growth of smooth muscle cells

Vessel is thickened

Lumen is narrowed

Less flexible

Primary Hypertension

Unknown etiology

One or more of the compensatory mechanisms has gone awry

Hypertension

Definition pg 353

Target Organs

Antihypertensive Drugs
Primary Hypertension

Angitensinconverting enzyme (ACE) Inhibitors (yes)

Angitensin II Receptor Antagonists (no)

Antiandrenergics (yes)

Calcium Channel Blockers (yes)

Diuretics (yes)

Angiotensin-Converting Enzyme Inhibitors (ACE Inhibitors)

Block the enzyme that converts angiotensin I to angiontensin II

Decrease vasoconstriction

Decrease aldosterone production

Prevent or reverse remodeling of heart and vessels

ACE Inhibitors

Caucasians-May be effective alone

African-Americans maybe used in combination with diuretic

ACE Inhibitor Prototype
Captopril (Capoten)

Choice for diabetic nephropathy

Renal protective

DOC for clients with CHF

23-4 p. 363

Side Effects

10-20 % experience persistent cough

Hypotension

Hyperkalemia

Renal failure

Sexual dysfunction

Contraindications

Pregnancy

Nursing Assessment

Check BP accurately and repeatedly

Monitor renal function

Hyperkalemia

Jaundice

Teaching

Give one hour ac

Continue to take even if feeling well

Antacids 2 hours before or after

Beta Blockers
269, Lilley

Decrease

Heart rate

Force of myocardial contraction

Cardiac output

O₂Demand by the heart

Renin release from the kidney

Stimulation from SNS

Beta Blocker

Drug of first choice

<50 with high renin hypertension

Tachycardia

Angina

MI

Left ventricular hypertrophy

Beta Blocker

Greater effect on Asians

African-American part of multi-drug regimen

Beta Blocker Prototype
Lopressor

Available PO & IV

Available in extended release

Cardio selective beta blocker

Side Effects

Fatigue

Bradycardia

CHF

Pulmonary Edema

Impotence

Nursing Assessment

Monitor BP, ECG, Pulse

I & O & daily weights

BUN

Liver function

Teaching

Pulse & BP at home

May cause drowsiness

Drug must be tapered

Impotence

Weight gain >2lb/wk

Use Carefully

Hepatic Impairment

Renal Impairment

Calcium Channel Blockers

Used for several CV disorders

In hypertension

Dilate peripheral arteries

Decrease vascular resistance

Choice for clients with angina

Can use for renal impairment

Use with caution with hepatic impairment

Calcium Channel Blockers Prototype: Diltiazem
(Cardizem SR)

Prevent movement of extracellular Ca into the cell

SR?

Slows the AV node

Decreases systemic vascular pressure

Contraindications

2^nd and 3^rd degree heart block

Cardiogenic shock

Congestive heart failure

Severe bradycardia

Hypotension

Side effects
Diltiazem (Cardizem SR)

Peripheral edema

Arrhythmias

CHF

Stevens Johnson Syndrome

Teaching

Do not crush, break, or chew

With or without meals

May cause drowsiness

Photosensitivity

Nursing Implications
All Antihypertensives

Therapeutic

Goal of tx is usually 140/90

Adverse Effects

Monitor postural hypotension

I & O

Bradycardia

Antiacids, andrenergics, & NSAIDS

Diuretics
Renal Physiology

Nephron processes (pg 378)

______ ______

______ ______

______ ______

Maintain fluid volume, electrolyte concentration, & pH

Cellular waste

400 ml/d

Glomerular Filtration

Pressure pushes H2O, electrolytes other solutes out

End product is approx 2L urine/d

Tubular Reabsorption

Most occurs in proximal tubule

Glucose, amino acids, and approx 80% of H2O, Sodium, Potassium, & Chloride

Loop of Henle

Descending limb H2O

Ascending Sodium

Distal Tubule

Exchange sodium & potassium

H2O

Antidiuretic Hormone (ADH) & Aldosterone

ADH promotes reabsorption of ____

Urine becomes more concentrated

Aldosterone promotes sodium-potassium exchange

Promotes sodium retention and potassium loss

Tubular Secretion

Proximal tubule

Uric acid, Cr, Hydrogen ions, & ammonia

Distal tubule

Potassium ions, hydrogen ions, & ammonia

Hydrogen balance maintains pH

Diuretics

Decrease blood pressure by sodium & water depletion

Initially, BV & CO are decreased

Eventually, CO normalizes but vascular resistance is decreased

May be used alone or in combination with anti-hypertensives

Thiazide Diuretics

Chemically related to sulfonamides

Decrease reabsorption of sodium, H2O, Chloride, & bicarb @ distal convoluted tubule

Not a strong diuretic

Ineffective for immediate diuresis

DOC for long term management

Thiazide Prototype
Hydrochorothiazide (Hydrodiuril)

Diuresis in about 2 hours

Promotes excretion of chloride, potassium, magnesium, & bicarb

Contraindications

Allergy to ____

Pregnancy

Loop Diuretics

Inhibit sodium & chloride reabsorption at the ascending limb of the loop of Henle

Significant diuresis, w/i 5 min (IV)

High ceiling

Postdiuretic phase may absorb more sodium

DOC in impaired renal function

Loop Diuretic Prototype
Furosimide (Lasix)

Most commonly used

Do not give if discolored

Ototoxicity

Side Effect
Hypokalemia

Serum potassium levels (what is normal?)

EKG

Hypotension

N&V, anorexia

Muscle weakness

Confusion

Teaching
Diuretics

Avoid excess table salt

Periodic serum potassium levels

Increase potassium rich foods

Diabetic?

Photosensitivity

Change positions slowly

Take with food

Potassium Sparing Diuretics

Distal tubule to decrease sodium reabsorption and potassium excretion

Weak diuretic

Usually in combination

Potassium Sparing Diuretics
Prototype: Spironolactone (Aldactone)

Aldosterone antagonist

Major side effect hyperkalemia

Do not use with renal insufficiency

Teaching

No salt substitutes

No potassium supplements

Contraindications

Renal failure

Nursing Implications
All Diuretics

Give in AM

I & O, daily weights, BP

Assess for edema

Monitor for coughing

Skin turgor

Hyperglycemia

Hyperuricemia

Pulmonary edema

Potassium Sparing

Hyperkalemia

Potassium over ?

ECG changes

Arrhythmias

Questions

The nurse is explaining HTN to a client. Which is the best explanation for why hypertension develops?

"Americans have a poor diet"

"Its is because of your sedentary lifestyle"

"we really don�t understand the reasons behind hypertension"

"one or more of the body�s compensatory systems has gone awry"

Questions

A client with an order for Furosimide (Lasix) is experiencing hypokalemia.

What should the nurse do?

A) Give the Furosimide with a K+ supplement

Give Spironolactone (Aldactone) STAT

Hold the Furosimide

Call the lab