Download Antihypertensive Agents

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
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
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
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
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
Antihypertensive Agents
•
Calcium Channel Blockers
Verapamil (Calan), Nifedipine (Procardia), Diltiazem (Cardizem)
- Free calcium muscle contractility,
peripheral resistance &
BP .
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,
So,