Lecture 6 Anti Hypertension

Antihypertensive Agents
Unit six
Lecture objectives
At the end of this lecture the student well
be able to:
1. Describe how blood pressure control
normally.
2. List causes of hypertension.
3. Give an example of drug that drugs which
lower Bp through different mechanism.
4. Discuss nursing implication.
• Medications used to treat hypertension
Classification of Blood Pressure
1. Primary Hypertension
Specific cause unknown, 90% of the cases,
Also known as essential or idiopathic
hypertension
2. Secondary Hypertension
Cause is known (such as eclampsia of
pregnancy, renal artery disease,
pheochromocytoma) 10% of the cases
Blood Pressure = CO x SVR
• CO = Cardiac output
• SVR = Systemic vascular resistance
The blood pressure depend on
• Systemic vascular resistance
(sympathetic)
• The output of blood from the heart
(sympathetic pulse rate increase)
• The volume and viscosity of the blood.
( ACE, diuretics
How drug can lowered blood
pressure
• Lower the systematic vesicular resistance
• Lower COP.
• Reduce blood volume
• Act centrally (CNS)
Antihypertensive Agents:
Categories
• Adrenergic agents (Sympathetic blocking
agent)
• Angiotensin-converting enzyme inhibitors
• Calcium channel blockers
• Diuretics
• Vasodilators
Sympathetic blocking agent
• Drugs Lower the systematic vesicular
resistance:
Adrenergic Agents
Alpha1 Blockers
• doxazosin (Cardura)
• prazosin (Minipress)
• terazosin (Hytrin)
Mechanism of Action
• Adrenergic Agents
• Alpha1 Blockers (peripherally acting)
• Block the alpha1-adrenergic receptors
– Result: vasodilation , improve the flow of urine.
• Stimulation of alpha1-adrenergic receptors

causes hypertension
Adrenergic Agents
• Therapeutic Uses
• Alpha1 blockers (peripherally acting)
– Treatment of hypertension
– Relief of symptoms of BPH
– Management of of severe CHF when used
with cardiac glycosides and diuretics

Side Effects
Most common: dry mouth drowsiness
sedation constipation
Other: headaches sleep disturbances

nausea rash cardiac
disturbances (palpitations)
HIGH INCIDENCE OF postural HYPOTENSION

Angiotensin-Converting Enzyme Inhibitors
(ACE Inhibitors)
• Large group of safe and effective drugs
• Often used as first-line agents for CHF
and hypertension
• May be combined with a thiazide diuretic
or calcium channel blocker
Antihypertensive Agents: Mechanism of
Action
• ACE Inhibitors
• RAAS: Renin Angiotensin-Aldosterone System
When the enzyme angiotensin I is converted to
angiotensin II, the result is potent vasoconstriction
and stimulation of aldosterone
• Result of vasoconstriction: increased systemic
vascular resistance and increased afterload
• Therefore, increased BP
Antihypertensive Agents: Mechanism of
Action
• ACE Inhibitors
• ACE Inhibitors block the angiotensin-converting
enzyme, thus preventing the formation of
angiotensin II.
• Also prevent the breakdown of the vasodilating
substance, bradykinin
–Result: decreased systemic vascular resistance

(afterload), vasodilation, and therefore, decreased
blood pressure
Examples ACE Inhibitors
• captopril (Capoten)
Short half-life, must be dosed more frequently
than others
• enalapril (Vasotec)
The only ACE inhibitor available in oral and
parenteral forms
• lisinopril (Prinivil and Zestril) and quinapril
(Accupril)
Newer agents, long half-lives, once-a-day dosing
Therapeutic Uses: ACE Inhibitors
• Hypertension
• CHF
• Slows progression of left ventricular hypertrophy after
an MI
• Renal protective effects in patients with diabetes
– Drugs of choice in hypertensive patients with CHF
Side Effects: ACE Inhibitors
1. Fatigue
2. Dizziness
3. Headache
4. Mood changes
5. Impaired taste
– Dry, nonproductive cough, reverses when therapy is
stopped
– NOTE: first-dose hypotensive effect may occur!!
Calcium Channel Blockers

• Cause smooth muscle relaxation by blocking the
binding of calcium to its receptors, preventing
muscle contraction
• This causes decreased peripheral smooth
muscle tone, decreased systemic vascular
resistance
• Result: decreased blood pressure
• Benzothiazepines:
– diltiazem (Cardizem, Dilacor)
• Phenylalkamines:
– verapamil (Calan, Isoptin)
• Dihydropyridines:
– amlodipine (Norvasc), bepridil (Vascor),
nicardipine (Cardene)
– nifedipine (Procardia), nimodipine (Nimotop)
Therapeutic Uses
• Angina
• Hypertension
• Dysrhythmias
Side Effects
Cardiovascular
hypotension, palpitations, tachycardia
Gastrointestinal
constipation, nausea
Other
rash, flushing, peripheral edema, dermatitis
Diuretics
• Decrease the plasma and extracellular fluid
volumes
• Results: decreased preload decreased
cardiac output decreased total peripheral
resistance
• Overall effect: decreased workload of the

heart, and decreased blood pressure
B blockers
• By interfering SNS they certainly prevent
the rise in COP, the ultimate goal of fall in
blood pressure.
• Decrease renin relase kidney.
• Uses:
• Lowering BP.
Examples B blockers
• Selective B blockers:
1. Atenolol
2. Esmolol
• Non selective:
• Propranolol
• Oxprenolol
• Combind alpha, B blockers
• Labetalol
Side effect
• Asthma
• Heart failure
• Diabetes
• Hallucination
Mechanism of Action
Vasodilators
• Directly relaxes arteriolar smooth muscle
• Result: decreased systemic vascular
response, decreased afterload, and
PERIPHERAL VASODILATION
Vasodilators
• diazoxide (Hyperstat)
• hydralazine HCl (Apresoline)
• minoxidil (Loniten, Rogaine)
• sodium nitroprusside (Nipride, Nitropress)
Therapeutic Uses
Vasodilators
• Treatment of hypertension
• May be used in combination with other agents
• Sodium nitroprusside and diazoxide IV are
reserved for the management of hypertensive
emergencies
Side Effects
Vasodilators
• Hydralazine:
– dizziness, headache, anxiety, tachycardia, nausea and
vomiting, diarrhea, anemia,
dyspnea, edema, nasal congestion
• Sodium nitroprusside:
– bradycardia, hypotension, possible
cyanide toxicity
Nursing Implications
• Before beginning therapy, obtain a thorough
health history and head-to-toe physical
examination.
• Assess for contraindications to specific

antihypertensive agents.
• Assess for conditions that require cautious

use of these agents.
• Educate patients about the importance of not
missing a dose and taking the medications
exactly as prescribed.
• Patients should never double up on doses if a

dose is missed; check with physician for
instructions on what to do if a dose is missed.
• Monitor BP during therapy. Instruct patients to

keep a journal of regular BP checks.
• Instruct patients that these drugs should not be
stopped abruptly, as this may cause a rebound
hypertensive crisis, and perhaps lead to CVA.
• Oral forms should be given with meals so that

absorption is more gradual and effective.
• Administer IV forms with extreme caution and

use an IV pump.
• Remind patients that medications is only part of
therapy. Encourage patients to watch their diet,
stress level, weight, and alcohol intake.
• Patients should avoid smoking and eating foods

high in sodium.
• Encourage supervised exercise.

• Instruct patients to change positions slowly to
avoid syncope from postural hypotension.
• Patients should report unusual shortness of

breath; difficulty breathing; swelling of the feet,
ankles, face, or around the eyes; weight gain or
loss; chest pain; palpitations; or excessive
fatigue.
• Men taking these agents may not be aware that
impotence is an expected effect. This may
influence compliance with drug therapy.
• If patients are experiencing serious side effects,

or believe that the dose or medication needs to
be changed, they should contact their physician
immediately.
• Hot tubs, showers, or baths; hot weather;
prolonged sitting or standing; physical exercise;
and alcohol ingestion may aggravate low blood
pressure, leading to fainting and injury. Patients
should
sit or lie down until symptoms subside.
• Patients should not take any other medications,

including OTC drugs, without first getting the
approval of their physician.
• Monitor for side/adverse effects
(dizziness, orthostatic hypotension, fatigue)
and for toxic effects.
• Monitor for therapeutic effects
• Blood pressure should be maintained at less

than 140/90 mm Hg

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Antihypertensive Agents

– Result: vasodilation , improve the flow of urine.

• Stimulation of alpha1-adrenergic receptors

with cardiac glycosides and diuretics

Other: headaches sleep disturbances

HIGH INCIDENCE OF postural HYPOTENSION

–Result: decreased systemic vascular resistance

Calcium Channel Blockers

• Overall effect: decreased workload of the

• Assess for contraindications to specific

• Assess for conditions that require cautious

• Patients should never double up on doses if a

• Monitor BP during therapy. Instruct patients to

• Oral forms should be given with meals so that

• Administer IV forms with extreme caution and

• Patients should avoid smoking and eating foods

• Encourage supervised exercise.

• Patients should report unusual shortness of

• If patients are experiencing serious side effects,

• Patients should not take any other medications,

• Monitor for therapeutic effects

• Blood pressure should be maintained at less

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