LEC - 7.3 - Vasodilators Flashcards
Reduce systolic and diastolic blood pressure by direct relaxation of vascular smooth muscle, thus lowering peripheral vascular resistance.
Vasodilators
Uses of vasodilators:
Moderate hypertension when 1st line fails – with beta blockers and diuretics
Reserved for severe hypertension or hypertensive emergencies
Examples of Vasodilators:
Nitroprusside
Hydralazine
Indications for Nitroprusside:
Severe hypertension, maintenance of controlled hypotension during anesthesia, acute heart failure
Actions of Nitroprusside:
Administrations:
Adverse effects:
Onset of action:
Acts directly on vascular smooth muscle to cause vasodilation and drop of blood pressure. It does not inhibit cardiovascular reflexes and tachycardia; renin release will occur
Used intravenously
Apprehension, headache, palpitations, cyanide toxicity, diaphoresis, nausea, vomiting, abdominal pain, irritation at the injection site
for IV route is 1-2 minutes
Nursing Implementation for Nitroprusside
Encourage the patient to implement lifestyle changes, including weight loss, smoking cessation, decreased alcohol and salt in the diet, and increased exercise, to increase the effectiveness of antihypertensive therapy.
Monitor blood pressure closely during administration to evaluate for effectiveness and to ensure quick response if blood pressure falls rapidly or too much.
Monitor blood glucose and serum electrolytes to avoid potentially serious adverse effects.
Monitor the patient carefully in any situation that might lead to a drop in fluid volume (e.g., excessive sweating, vomiting, diarrhea, dehydration) to detect and treat excessive hypotension that may occur.
Provide comfort measures to help the patient tolerate drug effects, including small, frequent meals; access to bathroom facilities; safety precautions if CNS effects occur; environmental controls; appropriate skin care as needed; and analgesics as needed.
Hydralazine is used in:
Fall in BP is caused by stimulation of adrenergic system leading to:
Cardiac stimulation producing palpitation and rise in CO preventing– anginal attack
Tachycardia
Increased Renin secretion – Na+ retention
The effects of Hydralazine are countered by administration of ___ and ___
beta blockers and diuretics
A powerful vasodilator and has 2 major uses – antihypertensive and alopecia
Rarely indicated in hypertension especially in life threatening ones
More often in alopecia to promote hair growth
Minoxidil
2 major uses of Minoxidil
antihypertensive and alopecia
Mechanism of action of hair growth:
Enhanced microcirculation around hair follicles and also by direct stimulation of follicles
Orally not used any more
Topically as 2-5% lotion/gel and takes months to get effects
are medicines that lower heart rate and reduce blood pressure. They block the signals from the brain to the nervous system that increase the heart rate and narrow blood vessels. As a result, the heart does not pump as hard. Blood flows more easily through the body’s veins and arteries.
Centrally Acting Drugs
Examples of Centrally-acting Drugs:
Alpha-Methyldopa
Clonidine
a pro drug
Alpha-Methyldopa
Mechanism of Action of Alpha-Methyldopa:
Converted to alpha methyl noradrenaline which acts on alpha-2 receptors in brain and causes inhibition of adrenergic discharge in medulla causing a fall in BP
Adverse effects of Alpha-Methyldopa
cognitive impairment, postural hypotension, positive Coomb`s test
Alpha-Methyldopa is not used therapeutically except in hypertension during pregnancy
NA
Imidazoline derivative, partial agonist of central alpha-2 receptor
Not frequently used because of tolerance and withdrawal hypertension
Clonidine
Indicated for the treatment of edema associated with congestive heart failure, acute pulmonary edema, liver disease (including cirrhosis), renal disease, and for the treatment of hypertension.
Diuretic Drugs
Diuretics are popular because they work quite well, are quite safe, well tolerated, and are not very expensive.
NA
Examples of Diuretics:
Thiazide and Thiazide- Like Diuretics
Loop Diuretics or “Potassium Wasting Diuretics”
Potassium Sparing Diuretics
Carbonic Anhydrase
___ are considered to be mild diuretics
Thiazide
___ are sulfa-based medications and a client with a sulfa allergy is at risk for allergic reactions.
Hydrochlorothiazide
___ act directly to dilate the smooth muscles in the arterioles. Because the arterioles are made larger, the heart does not have to pump so hard to get blood into them. This helps keep the blood pressure down.
Thiazides
Examples of Loop Diuretics or “Potassium Wasting Diuretics”
bumetamide (Burinex)
furosemide (Lasix)
Act by blocking active transport of chloride, sodium, and potassium in the thick ascending loop of Henle
Loop Diuretics or “Potassium Wasting Diuretics”
Often used in patients with kidney disease, CHF, and cirrhosis of the liver.
Loop Diuretics or “Potassium Wasting Diuretics”
Potassium Wasting Diuretics Side Effects:
Fatigue
Anorexia
Vomiting
Nausea
Muscle weakness
Leg cramps
Paresthesias
Decreased bowel motility
Examples of Potassium Sparing Diuretics
spironolactone (Aldactone)
triamterene (Dyrenium)
amiloride (Midamor)
Used for patients in whom a high risk of hypokalemia associated with diuretic use exists
Potassium Sparing Diuretics
Adverse effects of Potassium Sparing Diuretics:
hyperkalemia which can cause lethargy, confusion, ataxia, muscle cramps, and cardiac arrhythmias
Potassium sparing diuretics increase the excretion of water and sodium but save potassium.
NA
Examples of Carbonic Anhydrase
acetazolamide (Diamox)
Methazolamide
Relatively mild diuretics used to treat glaucoma because the inhibition of carbonic anhydrase results in ___
decreased secretion of aqueous humor of the eye
Adverse effects of Carbonic Anhydrase:
acid-base disturbances and electrolyte balance
The most common and potentially dangerous adverse effect related to an osmotic diuretic is the sudden drop in fluid levels
Osmotic Diuretic
Nausea, vomiting, hypotension, lightheadedness, confusion, and headache can be accompanied by cardiac decompensation and even shock
NA
Patients receiving mannitol should be closely monitored
NA
Examples of Osmotic Diuretics:
Mannitol (Osmitrol)
Route of administration for osmotic diuretics
Available only for intravenous use
Used in the prevention and treatment of acute renal failure
Reduction of intracranial pressure
Treatment of cerebral edema
Osmotic Diuretics
Nursing Implementation for Diuretic Drugs
Administer oral drug with food or milk
Administer IV diuretics slowly
Continuously monitor urinary output, cardiac response, and heart rhythm of patients receiving IV diuretics
Administer oral from early in the day
Monitor the dose carefully and reduce the dose of one or both drugs if given with antihypertensive
Monitor the patient response to the drug
Assess weight daily
Check skin turgor
Provide comfort measures, including skin care and nutrition consultation
