Antihypertensive Drugs
Hypertension (HTN) - An increase 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.
Secondary HTN is about 10% of HTN, related to endocrine or renal disorders
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
* Promote Na depletion decrease in extra cellular fluid (ECF)
* First line category in treatment of mild HTN
* Hydrochlorothiazide most frequently prescribed for first line Rx of mild HTN
* Can be used alone or with other anti HTN agents
1. BETA-ADRENERGICS
2. CENTRAL ACTING SYMPATHOLYTICS
3. ALPHA-ADRENERGICS
4. ADRENERGIC NEURON BLOCKERS
5. ALPHA & BETA ADRENERGIC BLOCKERS
e.g.: Atenolol (Tenormin), Metoprolol (Lopressor) - Beta-1 cardio selective
Propranolol (Inderal) -Nonselective Beta-1, Beta-2 blocker
- may be combined with a diuretic - Reduces cardiac output (CO) by
diminishing sympathetic nervous system response
- With continued use the vascular resistance diminished & BP lowered
- Reduces HR & contractility - Reduces renin release from kidneysNonselective = inhibits Beta-1 (heart) & Beta-2
(bronchial) receptors - HR slows & BP decreases - Bronchoconstriction occursCardio selective - Preferred - acts mainly on
Beta-1 receptors & bronchospasms less likely - not absolute
protection *Use cautiously in clients w/ pulmonary
history*
Clonidine HCL , Methyldopa - Stimulate Alpha-2 receptors decrease
sympathetic activity decrease epinephrine , nor epinephrine & decreases renin release decrease peripheral vascular resistance
- Can be used with other agents - Clonidine = a new transdermal preparation -
provides a 7 day duration of action- Used with diuretics – to prevent Na+ and fluid
retention- Do not D/C drug abruptly - HTN crisis possible
Prazosin HCl - Blocks alpha adrenergic receptors
vasodilatation & a decrease in BP - Helps maintain renal blood flow - Useful in clients with lipid abnormalities
- decrease VLDL & LDL - responsible for build-up of fatty plaques in arteries & increases HDL
- Can cause Na & H2O retention - diuretics may be added
• 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 other antihypertensive agent severe hypotension
* Potent drugs that block nor epinephrine form sympathetic nerve endings a decrease in nor epinephrine -> decrease in BP
* Decrease in both cardiac output & peripheral vascular resistance
Reserpine ,Guanethidine - Potent - used for severe HTN
These drugs used alone or with diuretics to decrease peripheral edema
* Common SE = Orthostatic Hypotension
Carvideolol , Labetalol - 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 decrease 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
Hydralazine - moderate. to severe HTN Sodium Nitroprusside - Very potent -
for hypertensive Emergencies - Act by relaxing smooth muscles of bld.
vessels - mainly arteries vasodilation - Increase blood flow to brain & kidneys - With vasodilation the BP decrease Na &
H2O retained peripheral edema. Diuretics used to
counter this SE- SE = numerous - tachycardia, palpitations,
edema, dizzyness, GI bleeding
Captopril, Enalapril , Lisinopril - 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 combination of Diuretic & ACE inhibitor.
Losartan , Telmesartan , Candesartan- 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 & decrease 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.
Verapamil , Nifedipine , Diltiazem - Free calcium muscle contractility,
peripheral resistance & BP . So, Calcium blockers decrease calcium
levels & promote vasodilation - Drugs can be used with patients prone to
asthma - SE. Flushing, headache, dizzyness, ankle
edema, bradycardia, AV node block,
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