Monday, August 31, 2009


DRUGS AFFECTING THE CARDIOVASCULAR SYSTEM

Anticoagulants
Prototype :
- Heparin (SQ and IV)
Warfarin (Orally)
Mechanism of actions :
a. Heparin
- prevents thrombin from converting fibrinogen to fibrin.
b. Warfarin
- suppress coagulation by acting as an
antagonist of vitamin K after 4-5 days.

Hemostasis :

Bleeding/injury
I
Vasoconstriction Plasminogen
I I
Platelet aggregation Plasmin
( temporary plug) I
I I
Clotting factor activation -------------- I
I I I
Intrinsic pathway (8,9,10,11,12) Extrinsic pathway (3,7,10) I
(PTT ) (PT) Vit K dep. I
I I I
I Prothrombin activation I I
I I
Thrombin I
I I
Fibrinogen ------------Fibrin threads ------------- Fibrin split products
(coagulation) ( Removed by liver & spleen )

Indications :
- thrombosis, pulmonary embolism, myocardial infarction
Adverse effect :
- bleeding
Nursing considerations :
1. HEPARIN sodium
- if given SQ don’t aspirate or rub the injection site (above the scapula - best site).
- therapeutic level 1.5-2.5 times normal PTT;
normal PTT is 20-35 sec. = 50-85 sec.
- antidote : (protamine sulfate)

2. WARFARIN sodium (coumadin)
- warfarin is used for long-term .
- onset of action is 4-5 days.
- therapeutic level is 1.5-2.5 times normal PT;
normal PT = 9.6 -11.8 sec. = 25 - 30 sec.
INR = 2 - 3
- should be taken at the same time of the day to maintain at therapeutic level.
- reduce intake of green leafy vegetables.
- antidote : Vitamin K ( Aquamephyton)

Thrombolytics
Prototype :
Streptokinase, Urokinase
Mechanism of actions :
- activates plasminogen to generates plasmin (enzyme that dissolve clots).
Indications :
- use early in the course of MI (within 4-6 hours of the onset)
Nursing considerations :
- monitor bleeding
- antidote : Aminocarpic acid

Antiplatelet Medications
Prototype: aspirin, Dipyridamole (Persantin)
Clopidoigrel (Plavix), Ticlopidine
Mechanism of action :
- inhibit the aggregation of platelet thereby prolonging bleeding time.
Indications :
- used in the prophylaxis of long-term complication following M.I, coronary
revascularization, and thrombotic CVA.
Nursing considerations :
- Monitor bleeding time ( NV = 1-9 mins)
- Take the medication with food.

Cardiac Glycosides
Prototype:
- digoxin (Lanoxin) and digitoxin (Crystodigin)
Mechanism of actions :
- increase intracellular calcium, which causes the heart muscle fibers to contract more
efficiently, producing positive inotropic & negative chronotropic action.
Indications :
- use for CHF, atrial tachycardia and fibrillation
Nursing considerations :
- Monitor for toxicity as evidence by :
nausea, vomiting, anorexia, halo vision, confusion, bradycardia and heart blocks .
- Do not administer if pulse is less than 60 bpm.
- Should be caution in patient with hypothyroidism and hypokalemia.
- Antidote : Digi-bind
- Phenytoin is the drug of choice to manage
digitalis-induced arrhythmia.


Nitrates
Prototype :
- isosorbide dinitrate (Isordil)
- nitroglycerine (Deponit, Nitrostat)
Mechanism of action :
- produce vasodilatation including coronary artery.
Indications :
- angina pectoris, MI, peripheral arterial occlusive disease.
Adverse effects:
- headache, orthostatic hypotension .

Nursing Considerations :
1. Transdermal patch
- apply the patch to a hairless area using a new patch and different site each day.
- remove the patch after 12-24 hours, allowing 10-12 hours “patch free” each day to
prevent tolerance.
2. Sublingual medications :
- note the BP before giving the medication.
- offer sips of water before giving because dryness may inhibit absorption.
- one tablet for pain and repeat every 5 mins. for a total of three doses; if not relieved
after 15 mins., seek medical help.
- stinging or burning sensation indicates that the tablet is fresh.
- instruct patient not to swallow the pill
- sustained release medications should be swallowed and not to be crush.
- protect the pills from light.




Anti-arrhythmic Drugs
Class I (block Na channels)
IA - quinidine, procainamide
IB - lidocaine
IC - flecainamide
Class II (Beta-blockers)
propanolol, esmolol
Class III (block K channels)
amiodarone, bretylium
Class IV (block Ca channels)
verapramil, diltiazem
Nursing considerations :
1. Watch out for signs of CHF.
2. Have client weigh themselves and report
weight gain.
3. Watch out for signs of lidocaine toxicity :
- confusion and restlessness

Antilipemics
Prototype :
a. cholesterol-lowering agents
- cholestyramine, colestipol, lovastatin
b. triglyceride-lowering agents
- gemfibrozil, clofibrate
Mechanism of actions :
- interfere with cholesterol synthesis as well as
decreasing lipoprotein & triglyceride synthesis.
Nursing considerations :
- monitor liver functions while using statins.
- prevent constipation, flatulence, cholelithiasis
- encourage increase fluid and fiber intake.

ANTI – HYPERTENSIVE

Angiotensin-Converting Enzyme (ACE) Inhibitors
Prototype :
captopril (Capoten), enalapril (Vasotec), quinapril, lisinopril
Mechanism of actions :
- prevent peripheral vasoconstriction by blocking conversion of angiotensin I to
angiotensin II decreasing peripheral resistance.
Adverse effect :
- it cause hyperkalemia
- induce chronic cough
Nursing considerations :
- not to discontinue medications because it can cause rebound hypertension.
- avoid using K+ sparing diuretics.

Calcium-Channel Blockers
Prototype :
- Nifedipine (calcibloc, adalat), Amlodipine (norvasc), Felodipine (Plendil)
Verapramil (Isoptin)
Mechanism of action :
- decrease cardiac contractility and the workload of the heart, thus decreasing the
need for O2.
- it also promote vasodilatation of the coronary and peripheral vessels.
Indications :
- hypertension, angina, arrhythmia
Adverse effects :
- bradycardia, hypotension, headache
- reflex tachycardia, constipation
Nursing considerations :
- Administer between meals to enhance absorption.
- Take client’s pulse rate before each dose, withhold if pulse is below 60 bpm.
- Refer for signs of congestive heart failure.

Diuretics
- usually given at morning
CARBONIC ANHYDRASE INHIBITORS
- Acetazolimide (Diamox)
- increase Na+, K+, & HCO3 secretion, along with it is H2O
- metabolic acidosis
OSMOTIC DIURETIC
- Mannitol
- Increase osmotic pressure of the glomerular filtrate.
- hypotension
THIAZIDE DIURETICS
- hydrochlorothiazide
- blocks Na and K reabsorption; reabsorb Ca
- hypercalcemia
LOOP DIURETICS
- Furosemide (Lasix)
- blocks Na, K, and Ca reabsorption
- hypocalcemia
POTASSIUM SPARING DIURETICS
- Spironolactone (Aldactone)
- excrete Na and water but it reabsorb K
- hyperkalemia

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