1. Antihypertensive Agents
Unit six

2. Lecture objectives
At the end of this lecture the student well be able to:
Describe how blood pressure control normally.
List causes of hypertension.
Give an example of drug that drugs which lower Bp through different mechanism.
Discuss nursing implication.

3. Antihypertensive Agents
Medications used to treat hypertension

4. Classification of Blood Pressure
1. Primary Hypertension
Specific cause unknown, 90% of the cases, Also known as essential or idiopathic hypertension
2. Secondary Hypertension
Cause is known (such as eclampsia of pregnancy, renal artery disease, pheochromocytoma) 10% of the cases

5. Blood Pressure = CO x SVR
CO = Cardiac output
SVR = Systemic vascular resistance

6. The blood pressure depend on
Systemic vascular resistance (sympathetic)
The output of blood from the heart (sympathetic pulse rate increase)
The volume and viscosity of the blood.( ACE, diuretics

7. How drug can lowered blood pressure
Lower the systematic vesicular resistance
Lower COP.
Reduce blood volume
Act centrally (CNS)

8. Antihypertensive Agents: Categories
Adrenergic agents (Sympathetic blocking agent)
Angiotensin-converting enzyme inhibitors
Calcium channel blockers
Diuretics
Vasodilators

9. Sympathetic blocking agent
Drugs Lower the systematic vesicular resistance:
Adrenergic Agents
Alpha1 Blockers
doxazosin (Cardura)
prazosin (Minipress)
terazosin (Hytrin)

10. Antihypertensive Agents: Mechanism of Action
Adrenergic Agents
Alpha1 Blockers (peripherally acting)
Block the alpha1-adrenergic receptors
Result: vasodilation , improve the flow of urine.
Stimulation of alpha1-adrenergic receptors causes hypertension

11. Antihypertensive Agents: Adrenergic Agents
Therapeutic Uses
Alpha1 blockers (peripherally acting)
Treatment of hypertension
Relief of symptoms of BPH
Management of of severe CHF when used with cardiac glycosides and diuretics

12. Side Effects Most common: dry mouth drowsiness sedation constipation
Other: headaches sleep disturbances nausea rash cardiac disturbances (palpitations)
HIGH INCIDENCE OF postural HYPOTENSION

13. Angiotensin-Converting Enzyme Inhibitors
(ACE Inhibitors)
Large group of safe and effective drugs
Often used as first-line agents for CHF and hypertension
May be combined with a thiazide diuretic or calcium channel blocker

14. Antihypertensive Agents: Mechanism of Action
ACE Inhibitors
RAAS: Renin Angiotensin-Aldosterone System
When the enzyme angiotensin I is converted to angiotensin II, the result is potent vasoconstriction and stimulation of aldosterone
Result of vasoconstriction: increased systemic vascular resistance and increased afterload
Therefore, increased BP

15. Antihypertensive Agents: Mechanism of Action
ACE Inhibitors
ACE Inhibitors block the angiotensin-converting enzyme, thus preventing the formation of angiotensin II.
Also prevent the breakdown of the vasodilating substance, bradykinin
Result: decreased systemic vascular resistance (afterload), vasodilation, and therefore, decreased blood pressure

18. Examples 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
lisinopril (Prinivil and Zestril) and quinapril (Accupril)
Newer agents, long half-lives, once-a-day dosing

19. Therapeutic Uses: ACE Inhibitors
Hypertension
CHF
Slows progression of left ventricular hypertrophy after an MI
Renal protective effects in patients with diabetes
Drugs of choice in hypertensive patients with CHF

20. Side Effects: ACE Inhibitors
Fatigue
Dizziness
Headache
Mood changes
Impaired taste
Dry, nonproductive cough, reverses when therapy is stopped
NOTE: first-dose hypotensive effect may occur!!

21. Calcium Channel Blockers
Cause smooth muscle relaxation by blocking the binding of calcium to its receptors, preventing muscle contraction
This causes decreased peripheral smooth muscle tone, decreased systemic vascular resistance
Result: decreased blood pressure

22. Calcium Channel Blockers
Benzothiazepines:
diltiazem (Cardizem, Dilacor)
Phenylalkamines:
verapamil (Calan, Isoptin)
Dihydropyridines:
amlodipine (Norvasc), bepridil (Vascor), nicardipine (Cardene)
nifedipine (Procardia), nimodipine (Nimotop)

23. Therapeutic Uses Calcium Channel Blockers Angina Hypertension
Dysrhythmias

24. Side Effects Calcium Channel Blockers Cardiovascular
hypotension, palpitations, tachycardia
Gastrointestinal
constipation, nausea
Other
rash, flushing, peripheral edema, dermatitis

25. Diuretics Decrease the plasma and extracellular fluid volumes
Results: decreased preload decreased cardiac output decreased total peripheral resistance
Overall effect: decreased workload of the heart, and decreased blood pressure

26. B blockers
By interfering SNS they certainly prevent the rise in COP, the ultimate goal of fall in blood pressure.
Decrease renin relase kidney.
Uses:
Lowering BP.

27. Examples B blockers Selective B blockers: Atenolol Esmolol
Non selective:
Propranolol
Oxprenolol
Combind alpha, B blockers
Labetalol

28. Side effect
Asthma
Heart failure
Diabetes
Hallucination

29. Antihypertensive Agents: Mechanism of Action
Vasodilators
Directly relaxes arteriolar smooth muscle
Result: decreased systemic vascular response, decreased afterload, and PERIPHERAL VASODILATION

30. Antihypertensive Agents
Vasodilators
diazoxide (Hyperstat)
hydralazine HCl (Apresoline)
minoxidil (Loniten, Rogaine)
sodium nitroprusside (Nipride, Nitropress)

31. Antihypertensive Agents: Therapeutic Uses
Vasodilators
Treatment of hypertension
May be used in combination with other agents
Sodium nitroprusside and diazoxide IV are reserved for the management of hypertensive emergencies

32. Antihypertensive Agents: Side Effects
Vasodilators
Hydralazine:
dizziness, headache, anxiety, tachycardia, nausea and vomiting, diarrhea, anemia, dyspnea, edema, nasal congestion
Sodium nitroprusside:
bradycardia, hypotension, possible cyanide toxicity

33. Antihypertensive Agents: Nursing Implications
Before beginning therapy, obtain a thorough health history and head-to-toe physical examination.
Assess for contraindications to specific antihypertensive agents.
Assess for conditions that require cautious use of these agents.

34. Antihypertensive Agents: Nursing Implications
Educate patients about the importance of not missing a dose and taking the medications exactly as prescribed.
Patients should never double up on doses if a dose is missed; check with physician for instructions on what to do if a dose is missed.
Monitor BP during therapy. Instruct patients to keep a journal of regular BP checks.

35. Antihypertensive Agents: Nursing 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.

36. Antihypertensive Agents: Nursing Implications
Remind patients that medications is only part of therapy. Encourage patients to watch their diet, stress level, weight, and alcohol intake.
Patients should avoid smoking and eating foods high in sodium.
Encourage supervised exercise.

37. Antihypertensive Agents: Nursing Implications
Instruct patients to change positions slowly to avoid syncope from postural hypotension.
Patients should report unusual shortness of breath; difficulty breathing; swelling of the feet, ankles, face, or around the eyes; weight gain or loss; chest pain; palpitations; or excessive fatigue.

38. Antihypertensive Agents: Nursing Implications
Men taking these agents may not be aware that impotence is an expected effect. This may influence compliance with drug therapy.
If patients are experiencing serious side effects, or believe that the dose or medication needs to be changed, they should contact their physician immediately.

39. Antihypertensive Agents: Nursing Implications
Hot tubs, showers, or baths; hot weather; prolonged sitting or standing; physical exercise; and alcohol ingestion may aggravate low blood pressure, leading to fainting and injury. Patients should sit or lie down until symptoms subside.
Patients should not take any other medications, including OTC drugs, without first getting the approval of their physician.

40. Antihypertensive Agents: Nursing Implications
Monitor for side/adverse effects (dizziness, orthostatic hypotension, fatigue) and for toxic effects.
Monitor for therapeutic effects
Blood pressure should be maintained at less than 140/90 mm Hg