2. 2
Therapeutic Agents for the Renal System
1. Describe the major components of the renal and urological
systems.
2. List the primary symptoms of conditions associated with
dysfunction of both the renal and urological systems.
3. Recognize prescription and over-the-counter drugs used to
treat the conditions associated with the renal and
urological systems as discussed in this chapter.
4. Write the generic and trade names for the drugs discussed
in this chapter.
5. List appropriate auxiliary labels when filling prescriptions
for drugs discussed for the treatment of conditions
associated with the renal and urological systems.
Lesson 21.1
3. Anatomy and Physiology of the
Renal and Urological Systems
Kidneys: Located inside upper abdominal cavity on
either side of vertebrae; bean shaped
Renal fascia: Fibrous connective tissue that holds
kidneys stationary
Renal artery: Where blood enters kidney
Blood is filtered in the kidney
Sodium and chloride reabsorbed into body and
circulatory system
Renal vein and ureter leave kidney via hilus
Renal vein returns blood to body after filtering process
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5. Questions
What is the function of the kidneys?
What are nephrons and where can they be seen on the
previous diagram?
What other organs excrete waste products from the
body?
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6. Renal and Urological Systems
Ureter carries waste removed from blood to bladder,
where it is stored for excretion
Bladder is a holding tank that can expand
Urine eliminated through urethra: Tube leading from
bladder to outside of body
During urination, the sphincter muscles relax to open
the bladder while the bladder (which is also a muscle)
contracts to squeeze out the urine.
Drugs are excreted through the renal system.
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7. Kidney Structure
7
From McCance KL: Pathophysiology: the biologic basis for disease in adults and children, ed 6, St Louis, 2010, Mosby.
8. Function of the Kidneys
Kidneys filter out and reabsorb nutrients and
chemicals
Waste eliminated by excretion
Four major functions of body:
Absorption
Distribution
Metabolism
Excretion
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9. Function of the Kidneys (Cont.)
Bladder holds up to 1000 mL of urine
Body excretes about 960 mL/day
Urine contains urea, produced by liver; form of
nitrogen that changes to ammonia
Kidneys balance fluid content of body
Fluids include water, blood, plasma, and ions
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10. Function of the Kidneys (Cont.)
Kidneys balance and eliminate ions within blood
Acidosis and alkalosis: Imbalance of ions in blood
Acidosis means too many free hydrogen ions
Alkalosis means too many hydroxide ions
Blood urea nitrogen (BUN) test determines levels of
acid in patient’s system
Kidneys filter about 50 gallons of blood products daily
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11. Nephron Function
Nephrons do all work of regulation of fluids, solutes,
and wastes in kidney
Each kidney contains millions of nephrons
Nephrons work 24 hours/day
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13. Tubular Reabsorption
Two mechanisms affecting balance of ions: Ion
exchange and active transport
Ion exchange: Sodium/hydrogen ion exchange (osmosis)
Sodium helps to conduct nerve impulses, so it is important for
it to be reabsorbed into the circulatory system.
Result: Decrease in excreted water
Active transport: One-way uptake of sodium and
chloride from loop of Henle
Result: Sodium returned to circulatory system
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14. Tubular Secretion
Tubular secretion takes place throughout the nephron
First, ions, toxins, and water are secreted into collecting
duct
Secretion and elimination of weak acids (aspirin and
penicillin) and weak bases (narcotic analgesics, metformin,
and antihistamines) takes place
Second, secretion allows kidneys to regulate pH of body
through urine acidification
Acidification: Process of eliminating extra hydrogen ions
through urine
Urine pH 4 to 5; blood pH is 7.4
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15. Tubular Secretion (Cont.)
Hydrogen ions combine to form bicarbonate
They are released into bloodstream to regulate overall
pH of body, maintaining homeostasis
Bicarbonate molecules act as a buffer because they can
either bind hydrogen ions [creating a basic environment
by decreasing the hydrogen ion concentration] or
release hydrogen ions [creating an acidic environment
by increasing the hydrogen ion concentration]).
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16. Importance of Electrolytes
Kidneys maintain balance through electrolytes in the
body
Specific cations and anions important
Cations include calcium, potassium, magnesium, and
sodium
Anions include chloride, bicarbonate, and phosphate
Electrolytes are required for the body. They are
important on the cardiac cycle, the balance of water,
the formation of teeth, and the growth of cells, for
instance.
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17. Conditions Affecting the Renal and
Urological Systems
Many people can live with only one kidney or partial
kidney function
Having less than 25% of normal kidney function causes
health problems. A patient with less than about 15% of
normal kidney function requires either dialysis or a
transplant for survival.
Dialysis and/or kidney transplant is sometimes
necessary
Other conditions include blockages, infections of
kidney, ureter, bladder, and urethra
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18. Chronic Kidney Disease
Progressive loss of renal function
Causes: Diabetes mellitus and uncontrolled
hypertension, glomerulonephritis, pyelonephritis, and
vascular disorders
Five stages based on glomerular filtration rate
Early symptoms: Fatigue, headache, shortness of
breath, weight changes, and edema
Dietary changes are important; protein restriction
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19. Treatment of Chronic Kidney
Disease: Dialysis
Waste products removed from blood
Compensates for lack of filtration
Two types: Hemodialysis and peritoneal dialysis
Hemodialysis: Patient must visit clinic or hospital
Peritoneal dialysis: Alternative to hemodialysis
Nocturnal dialysis: Treatment received while sleeping
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20. Negative aspects of dialysis
Additional medications patients must take to further
balance pH and fluids
The inconvenience of having to be stationary for a
length of time during a dialysis session
Even sophisticated machinery cannot perform as
efficiently as the body’s own kidneys.
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21. Drug Treatment for Chronic Kidney
Disease
Nutrients lost during hemodialysis must be replaced
by supplements
Vitamin supplements
Antihypertensives
Phosphorus-lowering medications
Vitamin D supplements
Kidneys are important in the synthesis of the active form of
vitamin D, which places people with CKD at risk of having
weak bones
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22. Kidney Stones
Kidney stones are small clumps of material that form
in the kidney from substances that pass through the
renal system
Cystine
Uric acid
Struvite
Calcium phosphate
Calcium oxalate
Kidney stones often do not cause any symptoms unless
they block the flow of urine.
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23. Drug Treatment for Kidney Stones
Calcium channel blockers and alpha blockers to help
speed up stone passing and reduce pain
To prevent stones:
Calcium: Thiazides and potassium citrate
Uric acid: Allopurinol and potassium citrate
Cystine: Captopril, tiopronin, and potassium citrate
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24. Alternative Treatments
Stones may pass on their own.
For larger stones, lithotripsy, ureteroscopes, and/or
surgery may be necessary.
The most commonly used surgical procedure for
kidney stone removal is extracorporeal shockwave
lithotripsy (ESWL). This procedure uses external
shock waves to break the stone into small particles,
which can be passed in the urine.
Drink water and limit caffeine intake.
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25. Edema
Causes: Congestive heart failure (CHF), hypertension
CHF: Heart muscle weakened by disease; decreases
efficiency; blood pumped less throughout body
Signs and symptoms include edema, chest pain, fatigue,
dyspnea, and orthopnea
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26. Edema (Cont.)
Heart failure (HF): Kidneys retain fluid, puts more
work on heart, creating vicious cycle
There is no cure for HF
Hypertension can damage heart muscle/veins, leads to
HF
Avoid salt and sitting for long periods of time
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27. Drug Treatment for Edema
Depends on underlying cause of the edema
Main drugs are:
Diuretic thiazides and thiazide-like agents
Loop diuretics and potassium-sparing diuretics
Carbonic anhydrase inhibitors
Osmotics
Two common beverage ingredients that are diuretics
Caffeine and alcohol
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28. Thiazides and Thiazide-like Agents
Drug action: Increase urinary excretion of sodium and
chloride ions equally
Inhibit normal process of reabsorption with ascending
tubule following loop of Henle and distal tubules
Increased loss of potassium and bicarbonate
Rapid onset of action
Side effect is frequent urination
Taken early in day to avoid nocturia
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29. Loop Diuretics
Loop diuretics inhibit reabsorption of sodium and
chloride in proximal convoluted tubule, distal
convoluted tubule, and loop of Henle
Great deal of potassium is lost with urination
They are taken early to avoid nocturia
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30. Potassium-Sparing Agents
These work primarily in distal convoluted tubule
They inhibit sodium reabsorption and decrease
potassium loss in urine
Large quantities of potassium-rich foods must be
avoided
Bananas, orange juice, and potatoes
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31. Osmotic Diuretics
Osmotic diuretics inhibit tubular reabsorption of
water by increasing osmolarity of glomerular filtrate
Used for prophylaxis of acute renal failure when
glomerular filtration is reduced
Agents include: Urea, glycerin, and isosorbide (also
used for glaucoma)
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32. Urinary Tract Infection
Urinary tract infections (UTIs) are a common cause of
bacterial infections
Most are caused by E. coli bacteria from the digestive
tract
Women more susceptible because of a shorter urethra
Catheterization is another cause
Kidney infection: Glomerulonephritis and
pyelonephritis
Bladder infection: Cystitis
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33. Symptoms of Urinary Tract
Infections
Symptoms of upper UTI:
Lower back pain, stomach pain, nausea, vomiting, and
headache
Symptoms of lower UTI:
Frequent but small amounts of urine, dysuria, and
sometimes incontinence
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34. Drug Treatment for Urinary Tract
Infections
Bacterial infections: Cephalosporin and
fluoroquinolone
Fungal infections: Fluconazole (Diflucan)
Tetracycline for infections caused by some sexually
transmitted diseases (STDs)
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35. Urinary Incontinence
Common urinary condition
Older adults, females, and women with multiple
pregnancies
Stress continence: Coughing, sneezing; force placed on
bladder; urine released
Urge incontinence has several causes: Decreased
bladder capacity, infection, and irritation
Risk increased by alcohol and caffeine ingestion
Common non-drug therapy treatment: Kegel exercises
(involve tightening of pelvic floor muscles)
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