Diuretics

Blood Pressure Review

Definition Per Davis’s Drug Guide for Nurses: – “Enhance the selective excretion of various electrolytes and water Different classes of diuretics work on different parts of the nephron: the proximal tubule, the loop of Henle, and the distal tubule.

Diuretics – A nephron is the functioning unit in the kidney that filters the blood. There are at least 1 million nephrons in each kidney. – One of the nephron’s primary jobs is to excrete and reabsorb sodium. – Sodium reabsorption in the distal tubule of the nephron is dependant on the action of aldosterone

Aldosterone Aldosterone, is a steroid hormone produced by the adrenal gland, and acts on the kidney nephron to conserve sodium, increase water retention, secrete (get rid of) potassium, and increase blood pressure.

Nephron

Diuretics General Information/Nursing Responsibilities: – Monitor clients taking Digoxin closely, as diuretics may contribute to Digoxin toxicity – Client Teaching- Best to take diuretics in the morning or at least not at night Daily weights should be recorded at home Notify physician for s/s of Dig toxicity – Visual disturbance, bradycardia, nausea, vomiting, and anorexia

MEDICATIONS

Antihypertensive Medications Onset of action- begins when drug enters the plasma Peak of action- highest serum concentration Half-life – time required for drug concentration in the body to be reduced by one half

Safe Medication Administration OSBN Nurse Practice Act – LPN Scope of Practice “The licensed practical nurse has the authority and responsibility to question any order which is not clear, perceived as unsafe, contraindicated for the client, or not within the [nurse’s] scope of practice.” [ paraphrase]

Diuretics THIAZIDE DIURETICS – Increase sodium and water excretion by inhibiting Na+ reabsorption in the distal tubule of kidneys – Not effective for immediate diuresis – Contraindicated in clients with renal failure  Use with caution in clients taking lithium  lithium toxicity Also use with caution in clients taking digoxin, corticosteroids, and hypoglycemic medications

Diuretics Examples: – Chlorthiazide (Diuril) – Hydochlorothiazide (HCTZ)(Hydrazide, HydroDiuril) – Metolazone (Zaroxolyn) Nursing: – Monitor labs (electrolytes, glucose, calcium, BUN, Cr, uric acid levels) – Monitor VS, checks for edema – Pt. teaching: diet, meds, BP self-checks, change positions slowly

Diuretics LOOP DIURETICS – Inhibit Na+ and Cl⁻ reabsorption from loop of Henle and distal tubule in kidneys – More potent than Thiazide diuretics  rapid diuresing  decreased vascular fluid volume, cardiac output, and BP  Use with caution in pt. taking lithium, digoxin, aminoglycosides, anticoagulants

Diuretics Loop (cont.) – Examples: Bumex, Lasix (furosemide) Nursing: – Observe for s/sx hypokalemia, hyponatremia, hypocalcemia, hypomagnesemia – Observe for orthostatic hypotension – Monitor labs, s/sx digoxin or lithium toxicity – Pt. teaching

Diuretics OSMOTIC DIURETICS – Increase osmotic pressure of the glomerular filtrate  inhibiting reabsorption of water and electrolytes – Used for oliguria and to prevent renal failure Example: Mannitol (Osmitrol) Nursing: – Monitor: I&O, wt., VS, labs, s/sx dehydration, pulmonary edema

Diuretics CARBONIC ANHYDRASE INHIBITOR – Inhibition of this enzyme (carbonic anhydrase)  increased Na+, K+, and bicarbonate excretion – Used to decrease intraocular pressure in open- angle glaucoma, and – Produce Diuresis, manage epilepsy, and treat high- altitude sickness Examples: Diamox, Naptazane

Diuretics POTASSIUM-SPARING DIURETICS – Act on the distal tubule of the kidneys to promote Na+ and H20 excretion and retention of K+ – Used for edema and HTN; increase urine output – Contraindicated in severe kidney or liver disease or severe hyperkalemia Examples: Aldactone (spironolactone); Aldactazide (spironolactone and hydochlorothiazide)

Diuretics POTASSIUM-SPARING DIURETICS (cont.) Nursing: – Monitor potassium levels that are > 5.1 mEq/L Adult Nml Range = 3.5 – 5.5 Critical values: 6.5 cardiac electrical activity can be seriously altered with development of arrhythmia – Monitor, teach/instruct s/sx hyperkalemia – Monitor VS and urine output – Take med with or after meals to ↓ GI irritation

ACE Inhibitors Angiotensin Converting Enzyme Inhibitor – Antagonist to the renin angiotensin-aldosterone system Angiotensin II produces vasoconstriction and stimulation of aldosterone – Prevent Angiotensin I conversion to Angiotensin II  vasodilation, ↓ BP, decreased systemic vascular resistance

Factors Influencing Blood Pressure

Remember... Aldosterone is a steroid hormone produced by the adrenal gland, and acts on the kidney to conserve sodium, secrete potassium, increase water retention, and increase blood pressure.

ACE Inhibitors Angiotensin Converting Enzyme Inhibitors – Examples (not a comprehensive list) Lisinopril (Prinivil, Zestril) Ramipril (Altace) Captopril (Capoten) Benzapril (Lotensin) – Side effects Dry cough Hypotension, hyperkalemia

ACE Inhibitors Client Teaching – Notify physician if: *Cough develops S/S of renal insufficiency or failure – Decreased urine output – Sediment in urine – Blood in urine

ACE Inhibitors Nursing: Pt. teaching: – Notify MD if: Cough develops s/sx renal insufficiency or failure – ↓ urine output – Sediment in the urine – Blood in the urine

Angiotensin II Antagonists Examples – Candesartan (Atacand) – Irbesartan (Avapro) – Losartan (Cozaar) – Valsartan (Diovan) Action – Allow angiotensin I to be converted to angiotensin II, but block the receptors that receive angiotensin II – Block vasoconstriction and release of aldosterone – Lower blood pressure

Angiotensin II Receptor Blockers Side Effects – Hypotension (orthostatic, dizziness) – Upper Respiratory Infection (URI) – Cough is much less prevalent than in ACE inhibitors Nursing: Client Teaching – Notify physician if s/s of infection dizziness

Calcium Channel Blockers Mechanism of action – Interrupts the flow of calcium into cells of cardiac muscle and vascular smooth muscle  relaxation of smooth muscle, decreasing cardiac muscle contraction and slowing electrical conduction (decreases heart rate) – Dilate peripheral arterioles and reduce peripheral resistance (systemic vascular resistance)

Calcium Channel Blockers Examples (not a comprehensive list!) – Amlodipine (Norvasc) – Diltiazem (Cardizem, Tiazac) – Felodipine (Plendil) – Nicardipine (Cardene) – Nifedipine (Procardia) – Verapamil (Calan)

Calcium Channel Blockers Side effects – Hypotension, bradycardia, worsening heart failure (edema), headaches Nursing: Client teaching – Check heart rate before taking medication – Notify physician of increased SOB, edema, bradycardia *Watch out for “extended release”* * Do not crush or chew!

Beta-Adrenergic Blocking Agents (Beta Blockers) Action – Block the release of the catecholamines epinephrine and norepinephrine  ↓ heart rate and BP – Decrease the workload of the heart and oxygen demand – Used for angina, dysrhytmias, HTN, migrain headaches, prevention MI, and glaucoma

Beta-adrenergic Blocking Agents Examples (not comprehensive) – Metoprolol (Lopressor) – Atenolol (Tenormin) – Carvedilol (Coreg) – Labetolol (Normodyne) – Toprol XL – Sotolol (Betapace) Adverse Effects – Bradycardia, hypotension, bronchoconstriction, fatigue, worsening heart failure (edema) – May also mask the symptoms of hypoglycemia

Beta-adrenergic Blocking Agents Nursing: Client teaching – Notify physician: If you are an asthmatic before taking this medication Increased SOB and/or edema – Check heart rate before taking medication and notify physician of bradycardia *Watch out for extended release* *Do not crush or chew!

Peripherally Acting Alpha-Adrenergic Blockers (Alpha Blockers) Examples – Doxasosin (Cardura) – Prazosin (Minipress) – Terasosin (Hytrin) Action – Decrease sympathetic vasoconstriction by reducing the effect of norepinephrine  vasodilation and ↓ BP – Used to treat HTN

Peripherally Acting Alpha- Adrenergic Blockers Adverse effects: – hypotension (orthostatic, dizziness), drowsiness, Na+ and H20 retention  edema Nursing: – Client teaching: Change positions from lying to standing slowly First dose after any change should be taken at night and then avoid hazardous activities for 12 hours Avoid OTC meds – Monitor VS, s/sx edema, orthostatic hypotension

Centrally Acting Sympatholytics (Adrenergic blockers) Examples – Clonidine (Catapres) – Methyldopa (Aldomet) – Guanfacine (Tenex) Action: – Stimulate alpha-receptors in the CNS to inhibit vasoconstriction  reduced peripheral resistance – Contraindicated in impaired liver function

Centrally Acting Adrenergic Blockers Adverse effects – Hypotension (orthostatic, dizziness), dry mouth, sedation/drowsiness Client Teaching – Change positions slowly – Take at bedtime if drowsiness occurs – Do not stop taking suddenly (Risk of rebound hypertension) – Take with food to slow absorption

Peripheral Vasodilators Examples – Hydralazine (Apresoline) – Minoxidil (Loniten) Action – Directly dilates peripheral arterioles  ↓ peripheral resistance  ↑ blood flow – Used in peripheral vascular disorders of arteries and veins – Sodium retention (minoxidil)

Peripheral Vasodilators Side Effects – Orthostatic Hypotension, tachycardia, lightheadedness, dizziness, paplitations Nursing: – Client Teaching Notify physician if: Dizziness, Preexisting CAD or Renal insufficiency Monitor blood flow to LE Instruct to not smoke Change positions slowly Avoid aspirin an aspirin-like products

Nursing Diagnosis Fluid Volume, risk for deficient – Check Orthostatic Blood Pressures!! – Teach client about appropriate fluid intake Normally there are not restrictions for HTN, but follow restrictions if ordered – Teach s/s of dehydration and advise client to have more intake if having these s/s