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,