Chapter 25- Antihypertensive Drugs Flashcards
A1-Blockers
Drugs that primarily cause arterial and venous dilation through their action on peripheral sympathetic neurons.
Antihypertensive Drugs
Drugs used to treat hypertension
Cardiac output
The amount of blood ejected from the left ventricle, measured in litres per minute
Centrally acting adrenergic drugs
Drugs that modify the function of the sympathetic nervous system in the brain by stimulating a2-receptors, which has a reverse sympathetic effect causing a decrease in blood pressure.
Essential hypertension
An elevated systemic arterial pressure for which no cause can be found an which is often the only significant clinical finding; AKA primary or idiopathic hypertension
Ganglionic blocking drugs
Drugs that prevent nerves from responding to the action of acetylcholine by occupying the receptor sites for acetylcholine on sympathetic and parasympathetic nerve endings.
Hypertension/Risk factor for
A common, often asymptomatic disorder in which blood pressure persistently exceeds 140/90mmHG
Risk Factor for: Stroke, Heart failure, coronary artery disease, cardiovascular disease, kidney failure. “Silent Killer”
Idiopathic hypertension
Hypertension with no known primary cause
Nicotinic receptor
The receptor and site of action for acetylcholine in both the parasympathetic and sympathetic nervous system.
Orthostatic hypotension
A common adverse effect of adrenergic drugs involving a sudden drop in blood pressure when patients change position, especially when rising from a seated or horizontal position.
Prodrug
A drug that is inactive in its administered for and must be biotransformed in the liver to its active form.
Secondary hypertension
High blood pressure known to be associated with with a primary disease, such as kidney, pulmonary, endocrine, or vascular disease.
Ethnocultural considerations
White people: B-blockers and ACE inhibitors more effective.
Black people: Calcium channel blockers and diuretics more effective
Canadian Hypertension Education Program (CHEP)
Endorses: Home BP monitoring, ongoing routine assessment. Lifestyle modifications: Healthy diet, regular physical activity, reduction in dietary sodium, stress reduction.
Target to treat: Less than 140/90. Less than 130/80 in PTs with diabetes or chronic kidney disease
Normal BP
120/80-129/89
Prehypertension
130/85-139/89
Stage 1 hypertension
140/90-159/99
Stage 2 hypertension
160+/100+
Unknown cause
Essential/idiopathic/primary hypertension. Accounts for 90% of cases
Known cause
Secondary hypertension. Accounts for 10% of cases
Masked hypertension
BP less than 140/90 in a medical setting but hypertensive at home
White-coat hypertension
BP less than 140/90 at home but hypertensive in a medical setting
PNS
Vasodilation of smooth muscle, cardiac muscle, glands
SNS
Constriction of heart, blood vessels, skeletal muscle
Adrenergic drugs
Prevent vasoconstriction.
Centrally and peripherally acting adrenergic neutron blockers
Centrally acting a2 receptor agonists
Peripherally acting a1 receptor blockers
Peripherally acting B receptor blockers (b1 blockers) both cardioselective(B1 receptors) and nonselective (both B1 and B2 receptors).
Peripherally acting dual a1 and B receptor blockers
Adrenergic drugs Mech of Action
Centrally acting a2 receptor agonists: Stimulate a2 adrenergic receptors in the brain.
Decrease sympathetic outflow from the central nervous system.
Decrease norepinephrine production
Peripheral a1 blockers/antagonists: Block a1-adrenergic receptors ex) prazosin (Minipress)-Prevent vasoconstriction.
B-Blockers: Reduce BP by reducing HR. cause reduced secretion of renin. Cause reduced peripheral vascular resistance. Result in decreased BP
Dual-action a1 and B receptor blockers: ex) Labetalol and carvedilol. Decrease BP.
Adrenergic Indications
Centrally acting a2 receptor agonists (brain): Usually used after other drugs have failed due to adverse effects.
Peripherally acting a1 receptor agonists: Treatment of hypertension. Relief symptoms of BPH, management of severe heart failure.
Adrenergic Contraindicatoins
Drug Allergy, Acute heart failure, concurrent use of MAOIs, Severe depression, peptic ulcer, asthma, severe live or kidney disease
Adrenergic Adverse effects
Dry mouth, sedation, drowsiness, constipation, headaches, palpitations. HIGH INCIDENCE OF ORTHOSTATIC HYPOTENSION
ACE inhibitors
First line drugs for heart failure and hypertension. May be combined with thiazide diuretic or calcium channel blocker
Ex) enalapril (Vasotec)- prodrug. captopril and lisinopril- NOT prodrugs. Used if a PT has liver dysfunction.
ACE inhibitor Mech of Action
Renin-angiotension-aldosterone system: Inhibits angiotension-converting enzyme so in the end prevents vasoconstriction. Aldosterone stimulates water and sodium resorption so there is an increase blood volume, increase preload, and increase BP- Do NOT want this!!!
ACE inhibitors block the angiotensin-converting enzyme, prevent the breakdown of vasodilating substance bradykinin. This decreases BP!
ACE Inhibitor Indications
Hypertension, heart failure, to slow progression of left ventricular hypertrophy after a MI, renal protective effects in PTs with diabetes. DRUG OF CHOICE FOR DIABETIC PATIENTS!!
ACE Inhibitor Contraindications
Drug allergy, lactating women, children, bilateral renal artery stenosis or hyperkalemia
ACE Inhibitor Adverse Effects
Fatigue, headache, impaired taste, dizziness, Dry, Nonproductive cough-#1 reason why people don’t tolerate this drug. People with Asthma not given this drug
ACE Inhibitor Interactions
NSAIDS, Lithium, Potassium supplements
Angiotension II Receptor Blockers (ARBs) Mech of Action
People with asthma use this! Allow angiotensin 1 to be converted to angiotensin II but block the receptors that receive angiotensin II,
Block vasoconstriction and release of aldosterone.
ex) losartan potassium (Cozaar), irbesartan (Avapro)
ARBs Indications
Treat hypertension, heart failure, may be used alone or with other drugs like diuretics, primarily used in PTs who cannot tolerate ACE inhibitors.
ARBs Contraindications
Drug allergy, pregnancy, lactation
ARBs Adverse Effects
Upper respiratory infections, headache, back pain, fatigue
ARBs Interactions
cimetidine, phenobarbital, rifampin
Calcium Channel Blockers Mech of Action
Cause smooth muscle relaxation by blocking the binding of calcium to its receptors, preventing muscle contraction. Decrease smooth muscle constriction
Calcium Channel Blockers Indications
Angina, Migraine headaches, hypertension, dysrhythmias, Raynaud’s diease
Diuretics
Decrease the plasma and extracellular fluid volumes which results in decreased preload, cardiac output, total peripheral resistance, for an overall effect of decreased workload of the heart and decreased BP
Thiazide Diuretics
First line antihypertensives in CHEP guidelines
Vasodilators Mech of Action
Directly relax arteriolar and venous smooth muscle
Ex) sodium nitroprusside (Nipride) IV pump. HYPERTENSIVE EMERGENCIES
Vasodilators Indications
Treat hypertension
Vasodilators Contraindications
Drug allergy, Hypotension, Cerebral edema, Head injury, MI, coronary artery disease
Vasodilators Adverse Effects
hydralazine: dizziness
sodium nitroprusside: Bradycardia, hypotension, possible cyanide toxicity (rare)
Nursing Implications
Before beginning a therapy: Obtain thorough head to toe assessment/health history.
Discuss importance of not missing a dose, should never never double up on doses, monitor BP, should not stop taking meds abruptly.
Oral forms should be given with meals so absorption is more gradual and effective.
Administer IV forms with extreme caution and use a pump.
Watch their diet, stress level, weight, alcohol intake, avoid smoking, and eating foods high in sodium
CHANGE POSITIONS SLOWLY!!!
Report unusual SOB, difficulty breathing, swelling of legs and feet.
Men can experience impotence
Hot tubs, showers, prolonged standing/sitting, may aggravate low BP and lead to fainting and injury.
PTs need to consult doctor before taking any OTC drugs.
Monitor for Adverse effects
Monitor for Therapeutic effects: BP less than 130/90 or 130/80 for diabetics and renal PTs
