Lecture 9 Chapter 39

1
Lecture 9Chapter 39

• Antihypertensive Drugs

2
AntihypertensiveAgents

• Hypertension (HTN) - An inc. in BP such that
  systolic is gt 140 mm/hg diastolic gt 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

3
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.
4
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 gt140 mm/hg antihypertensive
  meds started
• Pt. education compliance very important as in a
  good history

5
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

6
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
7
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

8
ANTIHYPERTENSIVE AGENTS
SYMPATHOLYTICS (SYMPATHETIC DEPRESSANTS) 1.
BETA-ADRENERGIC 2. CENTRAL ACTING
SYMPATHOLYTICS 3. ALPHA-ADRENERGICS 4.
ADRENERGIC NEURON BLOCKERS 5. ALPHA BETA
ADRENERGIC BLOCKERS
9
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

10
Antihypertensive AgentsBeta 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

11
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

12
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

13
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

14
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

15
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 mouthfatigue

16
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

17
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.

18
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

19
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.
20
AntihypertensiveAgents

• 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,

21
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 200mg Cross multiply

1 ml X ml
80 X 200 mg Immediately
divide by the number
on front of X
200 Reduce the fraction. 5
80
2
2.5 ml