Drugs used to treat Hypertension

HTN = BP > 140/90

Assos. With: premature death vascular disease of brain,

heart,kidneys

Goal of treatment

Prolong useful life by preventing cardiovascular problems by reducing

BP < 140/90

Blood Pressure

Review of physiology BP caused by: _________ Systolic pressure: __________ Diastolic pressure: __________

Blood Pressure Primary Factors

1. Cardiac output2. Peripheral resistance3. Blood Volume

Initial tx. of hypertension Lifestyle modification first No smoking Weight control Reduce alcohol intake Decrease stress Sodium control

Treatment of hypertension Lifestyle modification first Initial tx. drug- diuretic or B-blocker Low dose first, increase dose if

necessary 2nd med. if needed Most respond with diuretic and one

other medication (stepped care) Tx pump, fluid volume, or PVR

Drugs to treat hypertension

5 primary classes1. Diuretics2. Calcium channel blockers3. Angiotesin converting enzyme

(ACE) inhibitors4. Autonomic nervous system agents5. Direct acting vasodilators

Diuretics Tx: mild to moderate HTN First drug of tx. Also tx. heart failure or kidney

disease Few adverse side effects Used with other antihypertensives

to enhance effectiveness

DiureticsAction

Reduce blood volume through urinary excretion of water and electrolytes

1. Electrolyte imbalances can occur (mainly hypokalemia)

2. Depends on type of diuretic

Diuretics

Most efficient: Loop or High-ceiling Reduce edema assos. with CHF Increase UO even if blood flow to kidney

is diminished Hypokalemia KCL supplement given Lasix, Demadex, Bumex

Diuretics

Most widely prescribed: Thiazides Mild to moderate HTN-primarily Hydrodiuril – hydrochlorothiazide

(HCTZ) Hypokalemia Potassium supplement- KCL

Diuretics Potassium-sparing:prevent

hypokalemia Mild HTN Used in combination with other

diuretics No supplement taken Watch for hyperkalemia

Side effects Orthostatic hypotension Dry mouth,irritation Report: Electrolyte imbalance-

hypokalemia (potasium<3.5) Disorientation dehydration

Implications for use

Optimal time to admin.= AM Check VS Accurate intake and output Daily weights Monitor electrolyte imbalances

Calcium Channel Blockers

Emerged as major drug to tx. HTN Used for arrythmias also Alternative to B-blocker (hx.

Asthma)

Calcium Channel Blockers

Action:blocks ca+ access to muscle cells

contractility + conductivity of the ______________________ demand for oxygen PVR (relaxing arterioles)

Calcium Channel Blockers Examples Verapamil Very

Procardia (nifedipine)-HTN Nice

Cardizem (diltiazem)-arrythmias Drugs

Calcium Channel Blockers SIDE EFFECTS

BP Bradycardia May precipitate A-V block Headache Abdominal discomfort Peripheral edema

Angiotensin-Converting Enzyme Inhibitors “ACE” inhibitors Mainstay of oral vasodilator

therapy Major breakthrough in tx. of HTN More effective when used with

diuretics

ACE INHIBITORS

Angiotensin Converting Enzyme (ends in PRIL)

captopril enalapril benzapril(Capoten) (Vasotec) (Lotensin)

RENIN-ANGIOTENSIN-ALDOSTERONE AXN. BP

excrete renin

formation of angiotensin I angiotensin II = potent vasodilator Aldosterone release Na and H2O

ACE INHIBITORS ACTION

peripheral vascular resistanse without

Ø cardiac outputØ cardiac rate Ø cardiac contractility

Advantages Infrequent orthostatic hypotension Lack of aggravation of pulmonary

dx. Lack of aggravation with DM Increase renal blood flow

Side effects

Headache Orthostatic hypotension-infrequent Cough GI distress

Drug interactions Diuretics Alcohol Beta-blockers

All the above enhance the effects

Adrenergic ReceptorsReview of ANS

Sympathetic Nervous System Alpha 1 = vasoconstriction Alpha 2 = feedback/vasodilation Beta 1 = increases heart rate Beta 2 = bronchodilation

Beta Adrenergic Blocking Agents Known as Beta-blockers Axn: Inhibit cardiac response to

sympathetic nerve stimulation by blocking Beta receptors

Decreases heart rate and C.O. Decreases blood pressure

Beta Adrenergic Blocking Agents

Examples – “olol” names

Beta 1: Atenolol Beta 1 and 2: Propranolol

Nursing Implications

Can not be abruptly discontinued

Check baseline b.p. Check hx. of resp. condition-

aggravates bronchoconstriction

Side effects

Bradycardia Bronchospasm, wheezing Diabetic: hypoglycemia Heart failure:

edema,dyspnea,rhales

Interactions Antihypertensives- additive effect B-adrenergic agents- inhibit axn. Enzyme inducing agents-enhance

metabolism Indomethacin and salicylates:<

controll

Alpha-1 adrenergic blockers

Alternative if B-blockers and diuretics do not work

Also used to tx. mild to mod. urinary obstructive dx. (BPH)

Alpha-1 Adrenergic Blocking Agents

Action: Block postsynaptic alpha-1

adrenergic receptors to produce arteriolar and venous vasodilation

Reduces peripheral-vascular resistance

Side effects Drowsiness Headache Dizziness,tachycardia,fainting Weakness,lethargy

Interactions: other antihypertensives (enhance effects)

Clinical Implications Side effects most prevalent with

first dose Warn pt. that this is nl. Instruct pt. to lie down if

dizzy,weak,etc.

Examples of Apha-1 blockers

Cardura (doxizosin) Minipress (prazosin) Hytrin (terazosin)

Centrally Acting Alpha-2 Agonists Stimulate Alpha-2 receptors in

brainstem Decreases HR, SBP and DBP More frequent side effects –

drowsiness, dry mouth, dizziness Never suddenly DC = rebound HTN Clonidine – Catapres ( available in

TTS) Methyldopa - Aldomet

Direct Acting Vasodilators Action: dirct arteriolar smooth

muscle relaxation, decreasing PVR Uses: HTN, renal dx., toxemia of

pregnancy Ex: Apresoline, Minoxidel SE: tachycardia, orthostatic

hypotension,dizziness, palpitations, nausea, nasal congestion

Client Teaching forAntihypertensive drugs Take medication as prescribed Never discontinue without approval of

healthcare provider Incorporate lifestyle changes, even if

medication brings BP within nl. Limits Check BP on regular basis and report

significant variations (and pulse) Get out of bed slowly

Client Teaching forAntihypertensive drugs Increase intake of potassium-rich

foods, unless taking potassium sparing diuretics

Weigh regularly and report abnormal weight gains or losses

Do not take OTC drugs without checking with healthcare provider