Nursing 220: Pharmacology Module II: Renal System Drugs

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Nursing 220 PharmacologyModule II Renal
System Drugs

• Presented by
• Ronda M. Overdiek, MSN, CCRN, RNC

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Overview Renal System Drugs

• Chapter 39
• Anatomy
• Physiology
• Drugs Affecting Renal System
• Diuretics
• High ceiling (loop) diuretics
• Thiazide diuretics
• Osmotic diuretics
• Potassium sparing diuretics

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Review Nephron

• Nephron
• Functional unit of the kidney
• Function is to form a filtrate of protein-free
  plasma (process called Ultrafiltration)
• Approximately 1.2 million are present
• Tubular structure that contains
• Renal corpuscle (glomerulus, Bowman capsule)
• Proximal convoluted tubule
• Loop of Henle
• Distal convoluted tubule
• Collecting duct

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Review Nephron

• Renal Corpuscle
• Proximal Convoluted
• Tubule
• Loop of Henle
• Distal Convoluted
• Tubule
• Collecting Duct

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Process of Urine Formation

• Process of urine formation depends on
• 1. Glomerular Filtration formation of a
  filtrate of protein-free plasma
• 2. Tubular reabsorption Movement of fluids and
  solutes from the tubular lumen to the peritubular
  capillary plasma.
• 3. Tubular secretion Transfer of substances
  from the plasma of the peritubular capillary to
  the tubular lumen.

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Review Nephron
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Drugs of the Renal SystemDiuretics
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Drugs of the Renal SystemDiuretics

• Mechanism of Action
• Blockade of sodium and chloride reabsorption
• Create osmotic pressure within the nephron that
  prevents the passive reabsorption of water.
• Increase in urine flow that a diuretic produces
  is directly related to the amount of
  sodium/chloride reabsorption that it blocks.
• Diuretics that block reabsorption early in the
  nephron produce the greatest diuresis.
• 1 of solute reabsorption that is blocked, urine
  output will increase 1.8 L

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Drugs of the Renal SystemDiuretics

• Classifications of Diuretics
• High-Ceiling (loop) Diuretics
• Thiazide Diuretics
• Potassium-sparing Diuretics
• Osmotic Diuretics

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Diuretic ActionHigh Ceiling (Loop) Diuretics
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High-Ceiling (Loop) Diuretics

• Most effective diuretics available
• Produce more loss of fluid/electrolytes than any
  other diuretics
• Site of Action Loop of Henle
• Prototype Furosemide (Lasix)
• Acts of thick segment of the ascending limb of
  Henles loop to block reabsorption of sodium and
  chloride (normally 20 of filtered NaCl is
  reabsorbed)

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High-Ceiling (Loop) DiureticsFurosemide

• Pharmacokinetics
• Administered orally, IV, IM.
• Oral Begins 60 minutes-persists for 8 hours
• IV Begins 5 minutes persists for 2 hours
• Undergoes hepatic metabolism and renal excretion

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High-Ceiling (Loop) DiureticsFurosemide

• Why do we care when onset of action is?

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High-Ceiling (Loop) DiureticsFurosemide

• Therapeutic Uses
• Utilized by patients requiring rapid or massive
  mobilization of fluid
• Pulmonary edema
• Congestive heart failure (CHF)
• Edema of hepatic, cardiac, or renal origin that
  has been unresponsive to less efficacious
  diuretics
• Hypertension uncontrolled with other diuretics
• Severe renal impairment

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High-Ceiling (Loop) DiureticsFurosemide

• Adverse Effects
• Hyponatremia
• Hypochloremia
• Dehydration
• Hypotension
• Hypokalemia
• Ototoxicity
• Hyperglycemia (diabetic patients)
• Hyperuricemia (gout patients)

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Question 1

• Duncan McKeough is admitted to the
  medical-surgical unit with symptoms of shortness
  of breath and peripheral edema. Mr. McKeough is
  52 years old and has a history of recurrent
  congestive heart failure. An IV is started and
  he is to receive furosemide 40 mg IV. Furosemide
  is supplied in 10mg/ml. How much will you give
  Mr. McKeough?
• D/H X C DD

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Question 2

• The physician orders a maintenance dose of Lasix
  for Mr. McKeough. The nurse will check
  laboratory values and monitor for
• Hyperchloremia
• Hypermagnesemia
• Hypophosphatemia
• Hyponatremia

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Question 3

• Mr. McKeough is getting ready to go home. The
  physician writes for a discharge order to
  continue Furosemide 20 mg daily after discharge.
  The nurse will teach Mr. McKeough to
• Take the food on an empty stomach
• Eat foods high in calcium
• Weigh daily and report rapid changes
• Take medication in the evening

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Diuretic ActionThiazides
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Thiazides (Benzothiadiazides)

• Increase renal excretion of sodium, chloride,
  potassium, and water.
• Elevate plasma levels of uric acid and glucose
• Diuresis less than loop diuretics
• Loop diuretics effective in renal impairment,
  thiazides are not.

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Thiazides (Benzothiadiazides)

• Prototype Hydrochlorothiazide (HydroDIURIL)
• Mechanism of Action
• Blocks reabsorption of sodium/chloride in the
  early segment of the distal convoluted tubule.
  (10 of sodium and chloride reabsorbed at this
  site).
• Dependent on adequate kidney function
  ineffective when glomerular filtration rate (GFR)
  is low.
• Pharmacokinetics
• Onset 2 hours after oral administration-peaks
  4-6 hours, persist up to 12 hours.

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Thiazides (Benzothiadiazides)

• Therapeutic Uses
• Hypertension
• Edema (mild/moderate CHF)
• Adverse Effects
• Hyponatremia
• Hypochloremia
• Dehydration
• Hypokalemia
• Hyperglycemia (diabetics)
• Hyperuricemia (gout patients)

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Question 1

• Sam Weiss is being treated as an outpatient for
  mild hypertension. He is a 60 year old with a
  history of adult onset diabetes mellitus. Mr.
  Weiss is to begin treatment with chlorothiazide
  (Diuril) 500 mg PO daily. The nurse will note
  the following as important assessment data prior
  to administration
• Thyroid levels
• Gastric pH level
• Creatinine clearance
• Blood gas analysis

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Question 2

• Five days after starting diuretic therapy, Mr.
  Weiss calls to tell the nurse that he is having
  palpitations and skipped heart beats. The
  nurse informs the physician and is aware that
  these symptoms may relate to
• Hypermagnesemia
• Hyperglycemia
• Hyponatremia
• Hypokalemia

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Diuretic ActionPotassium Sparing Diuretics
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Potassium Sparing Diuretics

• Two useful responses
• Produce a modest increase in urine production
• Produce a substantial decrease in potassium
  excretion
• Used in conjunction with loop and thiazide
  diuretics
• Two Subcategories
• Aldosterone antagonists
• Nonaldosterone antagonists

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Aldosterone/ADH
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Aldosterone AntagonistSpironolactone (Aldactone)

• Spironolactone (Aldactone)
• Blocks the actions of Aldosterone in the distal
  nephron
• Opposite effect retention of potassium and
  excretion of sodium
• Onset 48 hours
• Therapeutic Uses
• Hypertension
• Edema
• Heart failure
• Hyperaldosteronism
• Used in combination w/loop or thiazide diuretics
• Counteract potassium wasting

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Aldosterone AntagonistSpironolactone (Aldactone)

• Adverse Effects
• Hyperkalemia
• Tumors
• Endocrine Effects

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Nonaldosterone AntagonistsTriamterene/Amiloride

• Mechanism of Action
• Inhibit potassium loss by direct blockade of
  sodium/potassium exchange in the distal nephron
• Produce only modest diuresis
• Used with other diuretics for potassium sparing
  effects (thiazides/loop)
• Adverse Effects
• Hyperkalemia

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Diuretic ActionOsmotic Diuretics
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Osmotic Diuretics

• Four Compounds
• Mannitol
• Urea
• Glycerin
• Isosorbide
• Most common Mannitol

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Osmotic Diuretics

• Mannitol (Osmitrol)
• Free filtered in the glomerulus
• Undergoes minimal reabsorption
• Not metabolized to a significant degree
• It is pharmacologically inert
• Mechanism of Action
• Creates osmotic force within the lumen of the
  nephron, inhibiting passive reabsorption of
  water, increasing urine flow.
• No significant effect on the excretion of
  potassium and other electrolytes.

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Osmotic DiureticsMannitol

• Pharmacokinetics
• Must be given IV.
• Distributes into extracellular water
• Diuresis begins 30-60 minutes, persists for 6-8
  hours.
• Therapeutic Uses
• Prophylaxis of renal failure
• Reduction of ICP
• Reduction of IOP

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Question

• Margaret Roberts, aged 47 years, is recovering
  from a craniotomy. The nurse monitors the
  intracranial pressure (ICP) and reports an
  elevated reading. Mannitol is administered as
  ordered. Which of the following outcomes BEST
  represents therapeutic effects of mannitol
  therapy for Ms. Roberts?
• Increased ICP
• Decreased peripheral edema
• Improved neurologic status
• Enhanced creatinine clearance

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Utilizing the Nursing Process

• Assessment
• Why does this patient need a diuretic?
• Assess medication history of drugs currently
  taken, including nonprescription drugs
• Baseline physical assessment
• Weight, blood pressure, pulse, respiration,
  electrolytes, record site/extent of edema
• Identify high risk patients
• Cardiovascular disease, renal impairment,
  diabetes, gout, pregnant.

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Utilizing the Nursing Process

• Nursing Diagnosis
• Knowledge deficit
• Fluid volume excess
• Fluid volume deficit
• Electrolyte Disturbances
• Planning
• Determine nursing goals derived from nursing
  diagnosis
• Plan of care is individualized to patient

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Utilizing the Nursing Process

• Implementation
• Administration Seven rights
• Promote Compliance
• Forewarn patients that treatment will increase
  urine volume and frequency

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Utilizing the Nursing Process

• Evaluation
• Monitor intake/output, blood pressure, pulse
  rate, weight patient daily, evaluate for
  decreasing edema.
• Minimize adverse effects
• Electrolyte imbalances, dehydration, hypotension,
  hyperglycemia, hyperuricemia.
• Drug interactions