NUR 106 (UNIT 5) Cardiovascular Therapy: Diuretic Drugs

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NUR 106 Pharmacology CCTC Fall 2011 Cheryl L DeGraw

First Line Drug Classes for Hypertension:

Angiotensin converting enzyme (ACE) inhibitors
Angiotensin II receptor blockers (ARBs)
Calcium Channel blockers
Beta-adrenergic antagonists
Diuretics

Tx generally starts c Diuretics

Second line (alternate) treatments for Hypertension:

Alpha1-adrenergic antagonists
Alpha2-adrenergic antagonists
Direct-acting vasodilators
Ganglionic Blocker
Renin Inhibitor

Diuretics are used to treat:

hypertension
heart failure
pulmonary edema
renal disease
liver cirrhosis/failure
glaucoma
hyperkalemia

when you get rid of fluid, you also get rid of electrolytes

Classes of Diuretics

Thiazide and Thiazide-like Diuretics (fairly weak)
Loop Diuretics (Lasix) (strong)
Carbonic Anhydrase Inhibitors (moderate)
Osmotic Diuretics (inter-cranial)
Potassium-Sparing Diuretics

Site of Action of Diuretics

Thiazide & Thiazide-like Diuretics examples

hydrochlorothiazide (HydroDIURIL)
bendroflumethiazide (Naturetin)
chlorothiazide (Diuril)
hydroflumethiazide (Diucardin, Saluron)
methyclothiazide (Aquatensen, Enduron)
chlorthalidone (Hygroton)
indapamide (Lozol)
metolazone (Mykrox, Zaroxolyn)

Thiazide Diuretics actions:

Keeps chloride and the sodium in the tubule to be excreted in the urine (wastes Na and Cl), thus preventing the reabsorption of both in the vascular system

Blocks reabsorption of bicarbonate (urine will be more base)

Thiazide Diuretics Drug-Drug

cholestyramine or colestipol
digoxin toxicity increases
Decreases effectiveness antidiabetic agents (may need to adjust the dose)
Increases quinine(malaria tx) toxicity & lithium(antipsychotic) toxicity

Thiazide Diuretics Contras

Allergy to thiazides or sulfonamides
Fluid and electrolyte imbalances, and renal and liver disease
Bipolar disorders

Thiazide Diuretics cautions

Gout
Systemic lupus erythematosus
Diabetes
Hyperparathyroidism
Pregnancy (B, C) and lactation

Thiazide and Thiazide-Like Diuretics Prototype: Hydrochlorothiazide: Indications

Adjunctive therapy for edema associated with CHF, cirrhosis, corticosteroid or estrogen therapy, and renal dysfunction; treatment of hypertension as monotherapy or in combination with other antihypertensives

Thiazide and Thiazide-Like Diuretics Prototype: Hydrochlorothiazide: Actions

Inhibits reabsorption of sodium and chloride in distal renal tubules, increasing the excretion of sodium, chloride, and water by the kidneys

Thiazide and Thiazide-Like Diuretics Prototype: Hydrochlorothiazide: PK:

Oral, 2 h, 4-6 h, 6-12 h
HL: 5.6-14 hours, liver, urine

Thiazide and Thiazide-Like Diuretics Prototype: Hydrochlorothiazide: AE/SE

Dizziness, vertigo, orthostatic hypotension, nausea, anorexia, vomiting, dry mouth, diarrhea, polyuria, nocturia, muscle cramps or spasms (build up of Ca leads to muscle spasms), headaches, decreased calcium excretion, hypokalemia, increased blood glucose levels, urine slightly alkalinized (HCO3 loss), dysrhythmias
(urine more alkaline -- increase risk of infection)

Theo is for REAL but don't give it to a BEAR

Theo = Thiazide

Renal (physical) dysfunction
Edema
Adjunct to hypertension
Liver Disease

Bi-polar
Electrolyte imbalance
Allergy to sulfonimides/Thiazide
Renal (chemical) Disease/Liver Disease

Loop Diuretics: furosemide (Lasix)

Most commonly used; less powerful than new drugs; larger margin of safety for home use

Loop Diuretics: bumetanide (Bumex) and torsemide (Demadex)

New drugs; more powerful than Lasix

Loop Diuretics: ethacrynic acid (Edecrin)

First loop diuretic introduced, used less frequently in the clinical setting

Loop Diuretics Actions

Block the chloride pump in the ascending loop of Henle
Decreases reabsorption of sodium and chloride - rapid diuresis (causes quick urination)

Loop Diuretics Interactions

Aminoglycosides or cisplatine
Anticoagulation
Indomethacin, ibuprofen, salicylates, or NSAIDs

Pregnancy Category C

Loop Diuretics Contras

Allergy
Electrolyte depletion
Anuria, Severe renal failure
Hepatic coma (the liver needs to be functional to metabolize the diuretic to avoid toxicity)
Pregnancy and lactation

Loop Diuretics Cautions

SLE, gout, and diabetes mellitus
Safety < 18 years of age not established

Loop Diuretics Prototype: Furosemide: Indicaitons

Treatment of edema associated with CHF, acute pulmonary edema, hypertension

Loop Diuretics Prototype: Furosemide: Actions

Inhibits the reabsorption of sodium and chloride from the proximal and distal renal tubules and the loop of Henle, leading to a sodium-rich diuresis

increase risk of hyponatremia

Loop Diuretics Prototype: Furosemide: PK:

Oral, 60 min, 60-120 min, 6-8 h
IV/IM, 5 min, 30 min, 2 h
HL: 120 min; liver, urine

Loop Diuretics Prototype: Furosemide: AE/SE

Dizziness, vertigo, paresthesias, blurred vision, orthostatic hypotension, thrombophlebitis, photosensitivity, rash, urticaria, nausea, anorexia, vomiting, constipation, glycosuria, urinary bladder spasm, leukopenia, anemia, thrombocytopenia, muscle cramps, and spasms, *hypokalemia, hypocalcemia, tachycardia, metabolic alkalosis, ototoxicity (8th cranial nerve damage -> tinnitus --> deafness)*

Bumetanide (Bumex) (memory)

used to help alleviate fluid in the lungs from congestive heart failure

T/F? The loop diuretics cause the body to excrete a copious amount of potassium-rich urine.

False

Rationale: The loop diuretics have a similar effect in the descending loop of Henle and in the distal convoluted tubule, resulting in the production of a copious amount of sodium-rich urine.

Carbonic Anhydrase Inhibitors: Actions

Block the effects of carbonic anhydrase; slow down the movement of hydrogen ions
More sodium and bicarbonate are lost in the urine (increases alkalinity of the urine)

Carbonic Anhydrase Inhibitors: Indications

Adjuncts to other diuretics
Glaucoma - decreases fluid

Carbonic Anhydrase Inhibitors Drug-Drug

Salicylates, corticosteroids, tricyclic antidepressants

Carbonic Anhydrase Inhibitors Contras

Allergy
Angle closure glaucoma (blocks fluid from draining out of the eye properly)

Carbonic Anhydrase Inhibitors Cautions

Lactation
Fluid or electrolyte imbalances
Renal or hepatic disease
Adrenocortical insufficiency
Respiratory acidosis
COPD

Pregnancy Category C

Carbonic Anhydrase Inhibitors Prototype: Acetazolamide: Indications

Adjunctive treatment of open-angle glaucoma, secondary glaucoma; preoperative use in acute angle-closure glaucoma when delay of surgery is indicated; edema caused by CHF, drug-induced edema; centrencephalic epilepsy; prophylaxis and treatment of acute altitude sickness

Carbonic Anhydrase Inhibitors Prototype: Acetazolamide: Actions

Inhibits carbonic anhydrase, which decreases aqueous humor formation in the eye, intraocular pressure, and hydrogen secretion by the renal tubules

Carbonic Anhydrase Inhibitors Prototype: Acetazolamide: PK:

Oral, 1 h, 2-4 h, 6-12 h
Sustained-release oral, 2 h, 8-12 h, 18-24 h
IV, 1-2 min, 15-18 min, 4-5 h
HL: 5-6 hours; excreted unchanged in urine

Carbonic Anhydrase Inhibitors Prototype: Acetazolamide: AE/SE

Weakness, fatigue, rash, anorexia, nausea, urinary frequency, renal calculi, bone marrow suppression, weight loss
*diarrhea, metabolic acidosis, hypokalemia, paresthesia, confusion, drowsiness*

Osmotic Diuretics Actions

Pull water into the renal tubule without sodium loss

Osmotic Diuretics Contras

Renal disease and anuria
Pulmonary congestion, HF
Intracranial bleeding, dehydration, shock
Pregnancy Category C

Osmotic Diuretics Drug-Drug

Increases excretion of many drugs:
salicylates, barbiturates, lithium, imipramine, & potassium supplements

Osmotic Diuretics Prototype: Mannitol: Indications

Prevention and treatment of oliguric phase of renal failure; reduction of intracranial pressure and treatment of cerebral edema; reduction of elevated intraocular pressure; promotion of urinary excretion of toxic substances; diagnostic use for measurement of glomerular filtration rate; irrigant in transurethral prostatic resection and other transurethral procedures. (irrigate prostate to prevent blood clot from forming)

Osmotic Diuretics Prototype: Mannitol:

Elevates the osmolarity of the glomerular filtrate, leading to a loss of water, sodium, and chloride; creates an osmotic gradient in the eye, reducing intraocular pressure; creates an osmotic effect that decreases swelling after transurethral surgery

Osmotic Diuretics Prototype: Mannitol:

IV, 30-60 min, 1 h, 6-8 h
Irrigant, Rapid, Rapid, Short
HL: 15-100 min; excreted unchanged in urine

Osmotic Diuretics Prototype: Mannitol:

Dizziness, headache, hypotension, rash, nausea, anorexia, dry mouth, thirst, diuresis, fluid and electrolyte imbalances
*tachycardia, confusion, convulsions, shock*
(risk of removing inter-cranial fluid too quickly)

Osmitrol (Mannitol) (memory)

Nursing Considerations - Potassium Wasting Diuretics

Measure BP, P before taking & regularly
Monitor: daily weight (report 3 lb increase)(same scale, same time, same clothing),
I & O, skin turgor, lung sounds, heart sounds
Rise slowly
Administer early in day, bathroom access
Provide K+ diet
Take with meals, milk to decrease GI upset
Monitor electrolytes - K+, Ca +, glucose
Adequate fluid intake - fluid rebound - page 816
Avoid extravasation if given IV

Potassium Rich Foods:

Avocados, Bananas, Broccoli, Cantaloupe, Dried fruits Grapefruit, Lima beans, Nuts, Navy beans , Oranges, Peaches, Potatoes, Prunes, Rhubarb, Sanka coffee, Sunflower seeds, Spinach, Tomatoes, Watermelon

Potassium-Sparing Diuretics Actions

Cause a loss of sodium while retaining potassium
Block the actions of aldosterone in the distal tubule
Highly protein bound (reduces effects of other protein bound drugs. can lead to lower protein bound drug toxicity die to increase in quantity in blood caused by displacement)

Potassium-Sparing Diuretics Indications

Adjuncts with thiazide or loop diuretics
Patients who are at risk for hypokalemia

Potassium-Sparing Diuretics Contras

Allergy
Hyperkalemia (can cause heart issues: cardiac arrest), renal disease, or anuria

Potassium-Sparing Diuretics Cautions

Pregnancy (Category B, C) and lactation

Potassium-Sparing Diuretics Drug-Drug

Salicylates
digoxin
Potassium supplements
Ammonium chloride

Potassium-Sparing Diuretics Prototype: Spironolactone: Indications

Primary hyperaldosteronism, adjunctive therapy in the treatment of edema associated with CHF, nephritic syndrome, hepatic cirrhosis; treatment of hypokalemia or prevention of hypokalemia in patients at high risk if hypokalemia occurs; essential hypertension

Potassium-Sparing Diuretics Prototype: Spironolactone:

Competitively blocks the effects of aldosterone in the renal tubule, causing loss of sodium and water and retention of potassium

Potassium-Sparing Diuretics Prototype: Spironolactone:

Oral, 24-48 h, 48-72 h, 48-72 h
HL: 20 hours; liver, urine

Potassium-Sparing Diuretics Prototype: Spironolactone:

Dizziness, headache, drowsiness, rash, cramping, diarrhea, hyperkalemia, hirsutism, gynecomastia, deepening of the voice, irregular menses, muscle weakness, paresthesis, bradycardia, decreased fertility, cardiac dysrhythmias

Nursing Considerations - Potassium-Sparing Diuretics

Measure BP, P before & at intervals
Administer in AM with food or milk
Daily weight (same clothes, time, scales)
Assess for signs of fluid retention
Teach to avoid salt substitutes or foods high in potassium and salt
Monitor I&O
Baseline & periodic electrolytes
Discontinue 3 days before glucose tolerance test due to risk of severe hyperkalemia

Spironolactone (memory)

normal potassium levels:

3.5 - 5 mg/dL

What is the most effective way for the nurse to evaluate effectiveness of diuretics?

pt's weight

John presents at the clinic with headaches due to stress. His blood pressure is 146/96 on two exams. The health care provider orders hydrochlorothiazide 25 mg daily.

What instructions does the nurse give John regarding this medication?

weight daily (report more than 3lb gain to HCP)
eat K rich foods
bathroom accessible
rise slowly (ortho-hypo)
GI upset (take c food or milk)
dry mouth
headache

Fluid Rebound Explained:

Care must be taken when using diuretics to avoid
fluid rebound, which is associated with fluid loss. If a patient stops taking inwater and takes the diuretic, the result will be a concentratedplasma of smaller volume. The decreased volume is sensed by the nephrons, which activate the renin-angiotensin cycle.When the concentrated blood is sensed by the osmotic center in the brain, antidiuretic hormone (ADH) is released to hold water and dilute the blood. The result can be a "rebound" edema as fluid is retained. Many patients who are taking a diuretic markedly decrease their fluid intake so as to decrease the number of trips to the bathroom. The result is a rebound of water retention after the diuretic effect. This effect can also be seen in many diets that promise "immediate results"; they frequently contain a key provision to increase fluid intake to 8 to 10 full glasses of water daily. The reflex result of diluting the system with so much water is a drop in ADH release and fluid loss. Some people can lose 5 lb in a few days by doing this.However, the body's reflexes soon kick in, causing rebound retention of fluid to re-establish fluid and electrolyte balance.Most people get frustrated at this point and give up the fad diet.It is important to be able to explain this effect. Teaching patients about balancing the desired diuretic effect with the actions of the normal reflexes is a clinical skill.

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