Antihypertensive Pharmacologic Agents

1. Antihypertensive Pharmacologic Agents NUR133 Lecture #11 K Burger, MSEd, MSN, RN, CNE Referenced from: Lilley et al (2005) Pharmacology and the nursing process (4th ed). Elsevier

2. Categories • Adrenergic agents -Alpha blockers -Beta blockers -Alpha/Beta blockers • Angiotensin-converting enzyme inhibitors • Angiotensin II receptor blockers • Calcium channel blockers • Vasodilators • Diuretics

3. Alpha Blockers (peripherally acting) Prazosin (Minipress) Blocks norepinephrine at receptor sites Sympathetic Nervous System not stimulated Blood vessel dilation results in decreased BP Alpha Blockers (centrally acting) Clonidine (Catapres) Reduces norepinephrine production Sympathetic Nervous System not stimulated Blood vessel dilation results in decreased BP Adrenergic Agents

4. Adrenergic Agents • Beta Blockers • atenolol (Tenormin) • metoprolol (Lopressor) • propranolol (Inderal) • Block SNS stimulation of heart; reduces SA node activity • Reduces ventricular contraction rate • Reduction in cardiac output results in lower BP • Also used as: Antidysrhythmic, Antianginal

5. Adrenergic Agents • Alpha / Beta Blocker Combination • Carvedilol ( Coreg ) • Dual antihypertensive effect on both CO and SVR • Alpha blocker promotes vasodilation; decreased SVR • Beta blocker reduces heart rate; decreased CO • Overall effect = decreased BP

6. Adrenergic AgentsNursing Implications • Orthostatic hypotension common;take alphas @ bedtime • Other side effects: fatigue, dizziness, sedation, constipation • Potentiates CNS depressants (Alcohol/Opiods) • Abrupt withdrawal of central alpha blocker causes rebound hypertension • Less side effects with peripheral acting and/or combination adrenergics • Monitor HR =>60 for beta blockers

7. Angiotensin-Converting Enzyme InhibitorsACE Inhibitors • Inhibit the conversion of Angiotensin I to Angiotensin II resulting in:Vasodilation,decreased SVR, decreased BP Decreased aldosterone,diuresis,decreased SVR&BP • May be combined with a thiazide diuretic or calcium channel blocker • Safe and effective; often used as first line Rx • Used also for: CHF, post MI to stop LVH progress • Renal protective effects in patients with diabetes

8. ACE Inhibitors • captopril (Capoten)Short half-life, must be dosed more frequently than others • enalapril (Vasotec)The only ACE inhibitor available in oral and parenteral forms • Newer agents, long half-lives, once-a-day dosing

9. ACE InhibitorsNursing Implications • Dry, nonproductive cough common • Other side effects: fatigue,dizziness,headache, mood changes • First-dose hypotensive effect may occur • Additive effects when given with diuretics or other antihypertensives • Antagonistic effects when given with NSAIDs • If given with K supplement may cause hyperK

10. Angiotensin II Receptor BlockersARBs • Losartan ( Cozaar ) • Valsartan ( Diovan ) • Block the binding of Angiotensin II to AT1 receptors on vessels & adrenal gland thereby:- promoting vasodilation / lower aldosterone- decreased SVR and decreased BP • Newer class and well-tolerated

11. ARBNursing Implications • Common side effects:Upper respiratory infectionHeadache • Less likely to cause hyperkalemia (unlike ACE) • Can be used in pts who cannot tolerate ACE Rx • Do not cause coughing • Used cautiously in geriatric pts and impaired renal function

12. Calcium Channel BlockersCCBs • Diltiazem (Cardizem) • Verapamil ( Calan ) • Nifedipine ( Procardia ) • Cause smooth muscle relaxation by blocking the binding of calcium to its receptors, preventing muscle contraction • This causes decreased peripheral smooth muscle tone, decreased SVR and BP • Slows cardiac conduction; decreases HR&CO&BP • Also used as : antidysrythmic, antianginal

13. Calcium Channel BlockersNursing Implications • Considered safe with limited side-effects • First line drug choice • More effective in geriatric and African-American patients • Possible side effects:hypotension, dysrythmias, constipation, nausea,rash,peripheral edema, dermatitis

14. Vasodilators • hydralazine HCl (Apresoline) • sodium nitroprusside (Nipride, Nitropress) • Directly relaxes arteriolar smooth muscle vasodilation; decreased SVR; decreased BP • May be used in combination with other agents • Sodium nitroprusside is reserved for the management of hypertensive emergencies

15. VasodilatorsNursing Implications • HydralazineSide Effects: dizziness, headache, anxiety, tachycardia • Sodium Nitroprusside Side Effects: bradycardia, hypotensionControlled administration/IV infusion pump

16. Antihypertensive Agents General Nursing Implications • Educate patients about the importance of not missing a dose, taking the medications exactly as prescribed, never doubling up on doses, and not stopping abruptly • Patients should not take any OTC drugs without first checking with MD • PO meds should be taken with meals • Educate patient on concurrent lifestyle modifications:Diet, Exercise, Stress Reduction • Instruct patients on how to monitor their own BP

17. Antihypertensive AgentsNursing Implications • Instruct patients that these drugs should not be stopped abruptly, as this may cause a rebound hypertensive crisis, and perhaps lead to CVA. • Oral forms should be given with meals so that absorption is more gradual and effective. • Administer IV forms with extreme caution and use an IV pump.

18. Antihypertensive Agents General Nursing Implications • Instruct patients to change positions slowly • Hot showers, tubs, weather, exercise, alcohol, prolonged sitting/standing may cause hypotension, dizziness, fainting • Patients should report: SOB, dyspnea, peripheral and/or angioedema, excessive weight gain, chest pain, palpitations • Men may experience impotence as expected SE

19. Diuretics Main classifications: • Thiazide and thiazide-like • Loop • Potassium-sparing Others: • Osmotic • Carbonic Anhydrase Inhibitors

20. Thiazide Diuretics • Hydrochlorothiazide ( HydroDIURIL ) • Inhibits Na reabsorption at distal tubule resulting in diuresis; decreased SVR & BP • Also acts to relax arterioles;decrease SVR • First line medication regimen for HTN • Safe for most patients; inexpensive • Often used in combination w/ other drugs

21. Loop Diuretics • Furosemide (Lasix) • Blocks Cl and Na reabsorption at Loop of Henle resulting in diuresis; decreased SVR and decreased BP • Stimulate prostaglandins; vasodilation ofrenal, lung, system vessels • Rapid onset and most potent diuretic • Can be given once daily • Effective even in renal impaired patients

22. Thiazide and Loop DiureticsNursing Implications • Monitor K levels closely for hypokalemia • Teach patient to eat high K foods • Cross allergies may exist to sulfonamides • Concurrent digoxin Rx may lead to digoxin toxicity • NSAIDS may decrease diuretic effect • Concurrent antiglycemic Rx may lead to hyperglycemia

23. Potassium-sparing Diuretics • Spironlactone ( Aldactone ) • Works in the collecting duct • Binds and blocks aldactone receptors resulting in blocked Na water reabsorption;decreased SVR and BP • Considered a weak diuretic • Often used in conjunction with more potent K depleting diuretics

24. Potassium-sparing DiureticNursing Implications • Monitor K levels closely for hyperkalemiaEspecially with renal impairment, use of potassium supplements, or ACE drugs • May cause gynecomastia, amenorrhea, and post-menopausal bleeding • Other side effects: dizziness, ha, cramps, nausea,diarrhea.

25. DiureticsGeneral Nursing Implications • Instruct patient to take early in the day to avoid sleep disturbances • Geriatric patients more sensitive to fluid balance changes; caution for postural hypotension • Monitor weights, potassium levels as well as Na and Cl • Instruct patients to notify MD if ill with vomiting and/or diarrhea