Antihypertensives Flashcards
Preload
Volume of blood in ventricles at the end of diastole
Afterload
Resistance left ventricle must overcome to circulate blood
Highest Contributor to Hypertension
Atherosclerosis
Normal Blood Pressure
S < 120
D < 80
Prehypertension
S 120-139
D 80-89
Stage 1 Hypertension
S 140-159
D 90-99
Stage 2 Hypertension
S > 160
D > 100
Primary Hypertension
No identifiable cause
Chronic, progressive disorder
Secondary Hypertension
Identifiable primary cause
Possible to treat the cause directly
Hypertension Medication Guidelines
Start medications in lowest available dose
Change medication groups instead of increasing dose if 1st medication is ineffective
Medication dosages are patient-specific
Clonidine and Methyldopa
Centrally acting adrenergic drugs
Stimulate alpha-2 adrenergic receptors in the brain
Decrease sympathetic outflow from CNS
Results in decreased BP
Methyldopa
Treats pregnancy-induced hypertension
Clonidine
Also used for opioid withdrawal
Metaprolol
Beta blocker
Reduces heart rate through beta-1 receptor blockade
Causes reduced secretion of renin
Long-term use causes reduced peripheral vascular resistance
Labetalol and Carvedilol
Dual-action alpha-1 and beta receptor blockers
Used for increased blood pressure
Dual antihypertensive effects of reduction in heart rate (beta-1 receptor blockade) and vasodilation (alpha-1 receptor blockade)
Carvedilol
Used for hypertension, mild to moderate heart failure in conjunction with digoxin, diuretics, and ACE inhibitors
Widely used drug that is well tolerated
Adrenergic Drugs
Used to treat hypertension, glaucoma, BPH, severe heart failure
Adrenergic Drugs Adverse Effects
HIGH INCIDENCE OF OTHROSTATIC HYPOTENSION
Bradycardia with reflex tachycardia
Drowsiness
Impotence
ACE Inhibitors
Large group of safe and effective drugs
Often used as first-line drugs for HF and HTN
May be combined with thiazide diuretic or CCB
Captopril and Lisinopril
ACE Inhibitors
NOT prodrugs (inactive in administered form and must be metabolized in the liver to an active form)
CAPTOPIL AND LISINOPRIL CAN BE USED IF A PATIENT HAS LIVER DYSFUNCTION, UNILKE OTHER ACE INHIBITORS THAT ARE PRODRUGS
ACE Inhibitors Mechanism of Action
Block ACE and prevent angiotensin II
Prevent breakdown of vasodilating substance bradykinin
Result in decreased afterload (SVR), vasodilation, and decreased BP
Prevent sodium and water reabsorption
Diuresis (decreases blood volume and return to the heart)
RENAL PROTECTIVE Effects of ACE Inhibitors
Reduce glomerular filtration pressure
Reduce proteinuria
Prevent progression of diabetic nephropathy
CARDIOPROTECTIVE Effects of ACE Inhibitors
Decrease SVR (a measure of afterload)
Used to prevent complications after MI
Ventricular remodeling after MI
Decrease morbidity and mortality in patients with HF
Drug of choice for hypertensive patients with HF
Adverse Effects of ACE Inhibitors
Dry, nonproductive cough (causes patients to stop medication)
Hyperkalemia
Captopril (Capoten)
Used for prevention of ventricular remodeling after MI
Shortest half-life
Must be administered PO multiple times throughout the day
Enalapril (Vasotec)
ONLY ACE INHIBITOR AVAILABLE IN BOTH ORAL AND PARENTERAL PREPERATIONS
Does not require cardiac monitoring
Oral enalapril is a PRODRUG
Reduces the incidence of HF
Angiotensin II Receptor Blockers
Well tolerated
Do not cause a dry cough
Allow angiotensin I to be converted to angiotensin II, but block receptors that receive angiotensin II
Block vasoconstriction and the release of aldosterone
Losartan (Cozaar)
Angiotensin II Receptor Blocker
Indications for ARBs
Hypertension
Adjunctive for the treatment of HF
May be used alone or with other drugs
ARB Adverse Effects
Chest pain, fatigue, hypoglycemia, diarrhea
Calcium Channel Blockers
PRIMARILY TREAT HYPERTENSION AND ANGINA
CAUSE SMOOTH MUSCLE RELAXATION BY BLOCKING BINDING OF CALCIUM TO ITS RECEPTORS, THEREBY PREVENTING CONTRACTION
Decrease SVR, BP, peripheral smooth muscle tone
Indications for CCBs
Angina, hypertension, dysrhythmias, migraines
Verapamil (Calan, Isoptin) and Diltiazem (Cardizem)
Calcium channel blockers
Can be given IV push followed by continuous infusion as well as PO
Used for atrial dysrhythmias
Amlodipine (Norvasc)
Calcium channel blocker, given in pills
Used for atrial dysrhythmias
Adverse Effects of Verapamil
Constipation is the most common complaint
Results from blockade of calcium channels in smooth muscle of intestine
Adverse Effects of Diltiazem
Less constipation, dizziness, flushing, headache, edema, exacerbates HF
Do not drink grapefruit juice
Diuretics
FIRST-LINE ANTIHYPERTENSIVES
DECREASE VOLUME AND PROTEINS
Decrease preload, CO, peripheral resistance, and overall workload and BP
Vasodilators
Typically used in emergency situations
Act directly on smooth muscle to cause muscle relaxation
Used for severe hypertension
Hypertensive Emergency
Blood pressure > 180/120 mmHg and must be lowered immediately to prevent damage to target organs
Hypertensive Urgency
Blood pressure is very high but no evidence of immediate or progressive target organ damage
Nursing Implications
African-Americans respond best to diuretics and CCBs as first line drugs
Instruct patients not to stop drugs abruptly
Administer IV forms with extreme caution and use IV pump for infusions
Remind patients that medication is only part of the therapy
Avoid salt substitutes due to high potassium
Instruct patients to report unusual SOB
