Antihypertensive Agents Guide: Types, Mechanisms & Uses

Antihypertensive Agents

INDIAN DENTAL ACADEMY
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Hypertension
High blood pressure
 Normal:

Systolic < 130 mm
Diastolic < 85 mm Hg


Hg

Classification of Blood Pressure
Category

Systemic BP (mm Hg)

Diastolic BP (mm Hg)

Normal

<130

<85

High normal

130-139

85-89

Hypertension
Stage 1
Stage 2
Stage 3
Stage 4

140-159
160-169
180-209
≥ 210

90-99
100-109
110-119
≥ 120


Classification of Blood Pressure
Primary Hypertension
 Specific cause unknown
 90% of the cases
 Also known as essential or idiopathic hypertension

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


Instructors may want to insert
EIC Image #69:
Blood Pressure: Normal Regulation


Medications used to treat hypertension


Antihypertensive Agents: Categories
Adrenergic agents
Angiotensin-converting enzyme inhibitors
Angiotensin II receptor blockers
Calcium channel blockers
Diuretics
Vasodilators



Adrenergic Agents






Alpha1 blockers
Beta blockers (cardioselective and nonselective)
Centrally acting alpha blockers
Combined alpha-beta blockers
Peripheral-acting adrenergic agents


Antihypertensive Agents: Mechanism of Action
Adrenergic Agents
Alpha1 Blockers (peripherally acting)
 Block the alpha1-adrenergic receptors
 The SNS is not stimulated
Result: DECREASED blood pressure

 Stimulation of alpha1-adrenergic receptors

causes HYPERtension
 Blocking alpha1-adrenergic receptors causes
decreased blood pressure

Antihypertensive Agents:
Adrenergic Agents
Alpha1 Blockers
 doxazosin (Cardura)
 prazosin (Minipress)
 terazosin (Hytrin)


Adrenergic Agents
Central-Acting Adrenergics
 Stimulate alpha2-adrenergic receptors
 Sympathetic outflow from the CNS is decreased

Result: decreased blood pressure


Adrenergic Agents
Central-Acting Adrenergics
 clonidine (Catapres)
 methyldopa (Aldomet)

(drug of choice for hypertension in pregnancy)


Adrenergic Agents
Adrenergic Neuronal Blockers
(peripherally acting)
 Inhibit release of norepinephrine
 Also deplete norepinephrine stores
 SNS (peripheral adrenergic nerves) is not stimulated

Result: decreased blood pressure

Adrenergic Agents
Adrenergic Neuronal Blockers
 reserpine
 guanadrel (Hylorel)
 guanethidine (Ismelin)


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


Adrenergic Agents

Therapeutic Uses
 Central-Acting Adrenergics


Treatment of hypertension, either alone or
with other agents



Usually used after other agents have failed
due to side effects



Also may be used for treatment of severe
dysmenorrhea, menopausal flushing, glaucoma



Clonidine is useful in the management of withdrawal
symptoms in opioid- or nicotine-dependent persons


Adrenergic Agents
Therapeutic Uses
 Adrenergic neuronal blockers




Treatment of hypertension, either alone or with other agents
Seldom used because of frequent side effects


Adrenergic Agents
Side Effects
Most common:
dry mouth
sedation
constipation
Other:
headaches
nausea
rash
disturbances (palpitations)

drowsiness
sleep disturbances
cardiac

HIGH INCIDENCE OF ORTHOSTATIC 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



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

ACE Inhibitors
 Aldosterone stimulates water and sodium resorption.
 Result: increased blood volume, increased preload, and

increased B


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


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
 Several other agents available

Antihypertensive Agents: Therapeutic Uses
ACE Inhibitors
 Hypertension
 CHF (either alone or in combination with diuretics

or other agents)
 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
 Fatigue

Dizziness

 Headache

Mood changes

 Impaired taste
Dry, nonproductive cough, reverses when therapy is stopped
NOTE: first-dose hypotensive effect may occur!!


Angiotensin II Receptor Blockers
Blockers or ARBs)
 Newer class
 Well-tolerated
 Do not cause coughing


(A II

 Allow angiotensin I to be converted to angiotensin II, but

block the receptors that receive angiotensin II
 Block vasoconstriction and release of aldosterone


 losartan (Cozaar)
 eposartan (Teveten)
 valsartan (Diovan)
 irbesartan (Avapro)
 candesartan (Atacand)
 telmisartan (Micardis)


 Hypertension
 Adjunctive agents for the treatment of CHF
 May be used alone or with other agents such

as diuretics


Side Effects
 Upper respiratory infections
 Headache
 May cause occasional dizziness, inability to sleep, diarrhea,

dyspnea, heartburn, nasal congestion, back pain, fatigue


Calcium Channel Blockers
 Benzothiazepines
 Dihydropyridines
 Phenylalkylamines


 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)


 Angina
 Hypertension
 Dysrhythmias
 Migraine headaches


Side Effects
 Cardiovascular


hypotension, palpitations, tachycardia

 Gastrointestinal


constipation, nausea

 Other


rash, flushing, peripheral edema, dermatitis


Antihypertensive Agents: 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



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)


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


Antihypertensive Agents: 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


Thank you
Leader in continuing dental education


Antihypertensive Agents Guide: Types, Mechanisms & Uses

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Antihypertensive Agents Guide: Types, Mechanisms & Uses