Transcript PowerPoint Presentation - Lecture 9

Lecture 9
Chapter 39
Antihypertensive Drugs
Antihypertensive
Agents
• Hypertension (HTN) - An inc. in BP such that systolic is
> 140 mm/hg & diastolic > 90 mm/hg on 2 or more
occasions after initial screening
• Essential HTN = most common. About 90% of clients.
* Exact Origin - unknown. Contributing Factors - family
hx, hyperlipidemia, African American background,
diabetes, obesity, aging, stress, excessive ETOH &
smoking.
• Secondary HTN is about 10% of HTN, related to
endocrine or renal disorders
Renin-angiotensin system
Kidneys and blood vessels strive to
regulate and maintain a “normal” BP.
The kidneys regulate blood pressure via
the renin-angiotensin system.
Renin (from the renal cells) stimulates
production of angiotensin I & then AT- II
(a potent vasoconstrictor), causes the
release of aldosterone (adrenal hormone
that promotes sodium retention and then
water retention). Retention of sodium and
water causes fluid volume to increase, thus
elevating blood pressure.
N.E. , an adrenal hormone of the
sympathetic nervous system, increases
blood pressure.
Hypertension
• Non-Pharmacological - Should be first line of
treatment. If successful, no meds. may be needed.
* Stress reduction techniques, exercise, salt
restriction, dec. in ETOH intake, no smoking, wt.
reduction
• Systolic pressure >140 mm/hg = antihypertensive
meds started
• Pt. education & compliance very important as in a
good history
Hypertension
• Pharmacological therapy - Individualized
* Want to start at lowest possible doses of meds.
* Reduce risk factors, even while on meds. - lifestyle
changes may allow the client to decrease medications.
* suggested after 1 yr. of therapy to dec. dose to determine
if less drug dose possible
• Step care hypertensive approach to treatment developed
several years ago - Classified by 4 stages based on BP
range. Pg. 695 table 39-1
• Individualized approach is also used - more modified to
each client. Pg. 696 - Table 39-3
STEPPED – CARE APPROACH
Step 1
Diuretic, Beta Blocker, Calcium blocker,
Angiotensin-converting enzyme
Step 2
Diuretic with beta blocker
Sympatholytics
Step 3
Direct-acting vasodilator
Sympatholytic with diuretic
Step 4
Adrenergic neuron blocker
Combinations from steps I, II & III
Antihypertensive
Agents
• Drugs used to treat Hypertension:
• Diuretics * Promote Na depletion  dec. in extra cellular
fluid (ECF)
* First line drug for Rx of mild HTN
* Hydrochlorothiazide (HydroDIURIL) most
frequently prescribed for first line Rx of mild HTN
* Can be used alone or w/ other antiHTN agents
ANTIHYPERTENSIVE
AGENTS
SYMPATHOLYTICS (SYMPATHETIC DEPRESSANTS)
1. BETA-ADRENERGIC
2. CENTRAL ACTING SYMPATHOLYTICS
3. ALPHA-ADRENERGICS
4. ADRENERGIC NEURON BLOCKERS
5. ALPHA & BETA ADRENERGIC BLOCKERS
Antihypertensive Agents
• 1) Beta-Adrenergic Blockers (Beta Blockers)
Atenolol (Tenormin), Metoprolol (Lopressor) Beta-1 cardio selective
Nadolol (Corgard), Propranolol (Inderal) Nonselective Beta-1, Beta-2
- Step 1 or 2 Rx - may be combined w/ a diuretic
- Reduces cardiac output (CO) by diminishing
sympathetic nervous system response
Antihypertensive Agents
Beta Blockers
- With continued use the vascular resistance diminished &
BP lowered
- Reduces HR & contractility
- Reduces renin release from kidneys
Nonselective = inhibits Beta-1 (heart) & Beta-2 (bronchial)
receptors
- HR slows & BP decreases
- Bronchoconstriction occurs
Cardio selective - Preferred - acts mainly on Beta-1
receptors
& bronchospasms less likely - not absolute protection
*Use cautiously in clients w/ pulmonary history*
Antihypertensive
Agents
• 2) Centrally Acting Sympatholytics (Adrenergic Blockers)
Clonidine HCL (Catapres), Methyldopa (Aldomet)
- Stimulate Alpha-2 receptors  dec. sympathetic activity
dec. epi., norepi. & dec.renin release  dec. peripheral
vascular resistance
- Can be used w/ other agents
- Clonidine = a new transdermal preparation - provides a 7
day duration of action
- Used w/ diuretics – to prevent NA+ and fluid retention
- Do not D/C drug abruptly - HTN crisis possible
Antihypertensive
Agents
• 3) Alpha - Adrenergic Blockers
Prazosin HCL (Minipress)
- Blocks alpha adrenergic receptors vasodilatation & a
dec. in BP
- Helps maintain renal blood flow
- Useful in clients with lipid abnormalities - decs. VLDL
& LDL - responsible for build-up of fatty plaques in
arteries & incs. HDL (friendly)
- Can cause Na & H2O retention - diuretics may be added
ANTIHYPERTENSIVE
AGENTS
• Safe for diabetics, do not affect respiratory function.
• Used in HTN, refractory CHF, Benign prostatic hypertrophy
(BPH)
• Side effects – dizziness, drowsiness, HA, N, V, &D.,
impotence, vertigo, urinary frequency, tinnitus, dry mouth
• Adverse - Orthostatic hypotension, palpitations, tachycardia
• When taken with ETOH or other antihyper.  severe
hypotension
Antihypertensive Agents
• 4) Adrenergic Neuron Blockers (Peripherally acting
sympatholytics)
* Potent drugs that block norepi. form sympathetic nerve
endings  a dec. in norepi.  dec. in BP
* Decrease in both cardiac output & peripheral vascular
resistance
Reserpine (Serpasil) & guanethidine (Ismelin) - Potent used for severe HTN
* Step IV drugs - alone or with diuretics to dec. peri. edema
* Common SE = Orthostatic Hypotension*
Antihypertensive Agents
• 5) Alpha-1 & Beta-1 Adrenergic blockers
Carteolol (Cartrol), Labetalol (Trandate)
- Blocks both alpha-1 & beta-1 receptors
- Block alpha-1 = dilation of arterioles & veins
-Effect on alpha receptors stronger than on beta receptors
so have a dec. BP & pulse rate
- Block beta-1 lead to decreased HR & AV contractility
- Large doses could block beta-2 receptors  inc. in air way
resistance - Do not give to severe asthmatics. AV block
SE = Orthostatic Hypotension, GI, nervousness, dry
mouth&fatigue
Antihypertensive
Agents
• Direct - Acting Arteriolar Vasodilators - potent
Hydralazine (Apresoline) - Mod. to severe HTN
Sodium Nitroprusside (Nipride) - Very potent - for
hypertensive Emergencies
- Act by relaxing smooth muscles of bld. vessels - mainly
arteries  vasodilation 
- Inc. blood flow to brain & kidneys
- With vasodilation the BP dec., Na & H2O retained
 peripheral edema. Diuretics used to counter this SE
- SE = numerous - tachycardia, palpitations, edema, dizzy,
GI bleeding
Antihypertensive Agents
• Angiotensin Antagonists - Angiotensin-Converting
Enzyme Inhibitors (ACE inhibitors)
Captopril (Capoten), Enalapril (Vasotec), Lisinopril (Zestril)
- Prevents conversion of Angiotensin I to angiotensin II
(vasoconstrictor) & blocks release of aldosterone.
Aldosterone promotes Na retention & K excretion. Block
aldosterone & Na excreted, but H2O & K retained
- Used to treat HTN primarily, - but not a 1st line drug.
Also used in heart failure.
- SE = hyperkalemia & 1st dose hypotension (more
common with comb. Diuretic & ACE inhibitor.
Antihypertensive Agents
• Angiotensin II receptor Antagonists (Blockers) - A - II
Blockers
Losartan (Cozaar)
- Newer drugs similar to ACE inhibitors + prevent release of
aldosterone (Na+ retaining hormone)
- Act on renin - angiotensin system
- Diff between ACE &AII is A-II blockers block
angiotensin from angiotensin I receptors found in many
tissues - blocks at receptor site.
- A-II blockers cause vasodilation & dec. peripheral
resistance
ACE inhibitors inhibit the
enzyme necessary for the
conversion of A-I to A-II
A-II blockers - block
angiotensin II from receptors
in blood vessels, adrenals, and
all other tissues.
Antihypertensive
Agents
• Calcium Channel Blockers
Verapamil (Calan), Nifedipine (Procardia),
Diltiazem (Cardizem)
- Free calcium muscle contractility, peripheral
resistance &
BP .
So, Calcium blockers
- Dec. calcium levels & promote vasodilation
- Drugs can be used w/ clients prone to asthma
- SE. Flushing, HA, dizzyness, ankle edema,
bradycardia, AV node block,
Math
A dosage of 200 mg must be prepared from a solution strength of 80 mg. per
ml. How many mls. should be given?
80 mg
1 ml
= 200mg
X ml
80 X = 200 mg
Cross multiply
Immediately divide by the number
on front of X
200 = Reduce the fraction.
80
2.5 ml
5
2