NURS 1950: Pharmacology
1
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Kidneys regulate
◦ Fluid volume, electrolytes, acid-base balance
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Kidneys secrete
◦ Renin- for blood-pressure regulation
◦ Erythropoietin – to stimulate blood-cell production
◦ Calcitrol –active form of vitamin D for bone
hemeostasis
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Urinary system consists of
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Two kidneys
Two ureters
One bladder
One urethra
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Objective 2: List the four processes carried
out by the nephron.
Objective 3: Name the part of the nephron
responsible for each process.
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Nephron is functional unit of kidney
Blood enters nephron and is filtered through
Bowman’s capsule
Fluid is called filtrate
Water and small molecules pass into proximal
tubule
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Filtrate passes through loop of Henle, then
distal tubule
Filtrate empties into collecting ducts and
leaves nephron as urine
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Filtrate in Bowman’s capsule is same
composition as plasma minus large proteins
Some substances in filtrate cross wall of
nephron and reenter blood
Most of water in filtrate is reabsorbed
Glucose, amino acids, sodium, chloride,
calcium, and bicarbonate are reabsorbed
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Some substances pass from blood through
walls of nephron and become part of filtrate
Potassium, phosphate, hydrogen, ammonium
ion, and some acid drugs are secreted into
filtrate
Reabsorption and secretion are critical to
pharmacokinetics of many drugs
Figure 30.1 The nephron
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Decrease in kidney’s ability to function
◦ Drugs can accumulate to high levels
◦ Medication dosages need to be adjusted
◦ Administering average dose to person in renal
failure can be fatal
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Urinalysis
Serum creatinine
Diagnostic imaging
Renal biopsy
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Glomerular filtration rate (GFR)
◦ Best marker for estimating renal function
◦ Measure volume of water filtered per minute
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Requires immediate treatment
Accumulation of waste products can be fatal
Most common cause is hypoperfusion
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Cause must be rapidly identified
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Heart failure
Dysrhythmias
Hemorrhage
Dehydration
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Occurs over months or years
Usually history of diabetes mellitus or
hypertension
May be undiagnosed for a long time
Nephrotoxic drugs can cause acute or chronic
renal failure
◦ See Table 30-1
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Attempts to cure cause of dysfunction
◦ Diuretics to increase urine output
◦ Cardiovascular drugs to treat hypertension or heart
failure
◦ Dietary management
 Restriction of protein, reduction of sodium, potassium,
phosphorus, magnesium
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Objective 4: pituitary hormone that influences
urine volume:
◦ ADH (Posterior pituitary)
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Objective 5: adrenocortical hormone that
influences urine volume:
◦ Aldosterone (increases Na+ reabsorption in the
distal tubule)
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Objective 6: four ways fluid is lost from the
body
◦ Urine, perspiration, lungs, stool
19
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Objective 7: describe the actions of diuretics
Diuretics act to
Deplete
blood volume
Excrete
sodium
Vasodilate
peripheral arterioles
(how is unknown)
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Increase rate of urine flow
Excretion of excess fluid used to treat
◦ Hypertension, heart failure, kidney failure
◦ Liver failure or cirrhosis, pulmonary edema
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Fluid and electrolytes disturbances
◦ Dehydration
◦ Orthostatic hypotension
◦ Potassium and sodium imbalances
Diuretics work in the kidney at
various sites of the nephron
 Can interfere with the action of
aldosterone causing loss of sodium
◦ Where goes sodium, so goes water
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What happens with diuretics
◦ Decrease excess water
◦ Loop diuretics + 0.9% NaCl = loss of
calcium
◦ Decrease excess NaCl
◦ Decrease cerebral edema (Mannitol)
◦ Decrease increased IOP (Diamox)
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Mannitol is an osmotic diuretic (a
sugar);
◦ in the brain, its presence causes
water to be drawn to it
 Works the same way in the eye:
◦ the excess intraocular fluid is drawn
to the mannitol in the hyperosmotic
plasma
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◦ Diamox very weak diuretic
 Useful in treating glaucoma
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◦ Aminophylline
◦ Theophylline
◦ Caffeine
◦ Theobromine
 Diuretic effect from improved blood
flow to kidney
 Generally not used for diuretic
effect
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 Drugs
that affect the loop of
Henle
◦ Bumetanide (Bumex)
◦ Ethacrynic acid (Edecrin)
◦ Furosemide (Lasix)
◦ Torsemide (Demadex)
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Act in the loop of Henle in the kidney
◦ Inhibits Na and Cl reabsorption
 Some increase blood flow to glomeruli
 Inhibits electrolyte absorption in
proximal tubule
◦ Lose sodium, chloride, potassium,
magnesium, sodium bicarbonate
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 Onset
of diuretic effect varies,
but is within 1-2 hours. IV,
drugs work within 5-10
minutes
 Peak effect within 1-2 hours
 Duration approximately 6
hours
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Maximum mg/day
◦ Bumex 10 mg per 24 hours
◦ Edecrin 400 mg per 24 hours
◦ Lasix 1000 mg/24 hours
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Cross sensitivities
◦ Sulfonamides and Lasix, Demadex
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SE to expect
◦ Oral irritation
◦ Dry mouth
◦ Orthostatic hypotension
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SE to report with loop diuretics
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GI irritation, abdominal pain
Electrolyte imbalance, dehydration
Hives, pruritus, rash
Some can cause loss of hearing and hyperglycemia
(interfere with hypoglycemic agents)
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Drug interactions
◦ Alcohol, barbiturates, narcotics
◦ Aminoglycosides
◦ Cisplatin
◦ NSAIDs
◦ Corticosteroids
◦ Probenecid
◦ Digoxin
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Loop diuretics include
◦ Bumetanide (Bumex)
◦ Ethacrynic acid (Edecrin)
◦ Furosemide (Lasix)
◦ Torsemide (Demadex)
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Loop or high-ceiling are most effective
diuretics
Mechanism of action: to block reabsorption
of sodium and chloride in loop of Henle
Primary use: to reduce edema associated with
heart, hepatic, or renal failure
Furosemide and torsemide also approved for
hypertension
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Obtain baseline and monitor periodically lab
values, weight, current level of urine output
Monitor electrolytes, especially potassium,
sodium, and chloride
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Monitor blood urea nitrogen (BUN), serum
creatinine, uric acid, and blood-glucose levels
Assess for circulatory collapse, dysrhythmias,
hearing loss, renal failure, and anemia
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Monitor for side effects orthostatic
hypotension, hypokalemia, hyponatremia,
polyuria
Observe for rash or pruritis
Teach clients to take diuretics in the morning,
change position slowly, monitor weight
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Clients should take potassium supplements,
if ordered, and consume potassium–rich
foods
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Action of the thiazides
◦ Act on the distal tubules of the kidney
 Block reabsorption of sodium and chloride ions
from the tubule
 The unreabsorbed Na and Cl ions pass into the
collecting ducts, taking water with them
Thiazides have antihypertensive properties because
of direct vasodilation effect on peripheral arterioles
◦ Expected outcomes from treatment
 Decreased edema and improvement of
symptoms RT excess fluid accumulation
 Reduction in BP
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Assessments
◦ Mental status
◦ Diabetics require baseline blood glucose
◦ Assess hearing
◦ Assess for symptoms of acute gout
SE to expect: orthostatic hypotension
◦ Usually in initial stages of treatment
◦ Teach client safety measures
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SE to report
◦ GI irritation, N/V, constipation
◦ Electrolyte imbalance, dehydration
◦ Hyperuricemia
◦ Hyperglycemia
◦ Hives, rash
Thiazides can interact with
◦ Digoxin, corticosteroids
◦ Lithium, NSAIDs
◦ Oral hypoglycemic agents
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 Thiazides
can interact with
◦ Digoxin, corticosteroids
◦ Lithium, NSAIDs
◦ Oral hypoglycemic agents
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Thiazide diuretics include
◦ Bendroflumethiazide (Naturetin)
◦ Chlorothiazide (Diuril)
◦ Hydrochlorothiazide (HCTZ) {Esidrix,
HydroDiuril}
◦ Polythiazide (Renese)
◦ Trichlomethiazide (Naqua,
Metahydrin, Diurese)
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 Thiazide-like
drugs include
◦Chlorthalidone (Hygroton)
◦Indapamide (Lozol)
◦Metolazone (Zaroxolyn)
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Largest, most commonly prescribed class of
diuretics
Mechanism of action: to block Na+
reabsorption and increase potassium and
water excretion
Primary use: to treat mild to moderate
hypertension
◦ Also indicated to reduce edema associated with
heart, hepatic, and renal failure
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Less efficacious than loop diuretics
◦ Not effective in clients with severe renal failure
 Why
is there concern about the
electrolyte balance?
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Weak antihypertensives
 Mechanism of action unknown
 Do work in distal renal tubule
◦ Retains potassium
◦ Excretes sodium
◦ Some have anti-aldosterone activity
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Maximum dosing per 24 hrs
◦ drug dependent
 SE to expect with Midamor:
◦ anorexia, N/V, flatulence and HA
 SE to report:
◦ electrolyte imbalance, dehydration,
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SE to expect and report with
Aldactone and Dyrenium:
◦ mental confusion, HA, diarrhea,
electrolyte imbalance, dehydration,
gynecomastia, reduced libido, breast
tenderness
 Dyrenium can also cause allergic
reaction (hives, pruritus, rash)
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Generally, drug interactions for the K+
sparing agents
◦ Lithium, ACE inhibitors, salt substitutes, K+
replacement
◦ NSAIDs,
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Potassium-sparing drugs include
◦ Amiloride (Midamor)
◦ Spironolactone (Aldactone)
◦ Triamterene (Dyrenium)
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 Potassium-sparing
drugs include
◦ Amiloride (Midamor)
◦ Spironolactone (Aldactone)
◦ Triamterene (Dyrenium)
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Advantage: diuresis without affecting blood
potassium levels
Mechanism of action: either by blocking
sodium or by blocking aldosterone
Potassium-sparing diuretics shown in Table
30.5
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Why is an adequate fluid intake important
with diuretic therapy?
If the client has to get up during the night to
void, what will they probably do?
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Cannot be classified as loop, thiazide, or
potassium-sparing agents
Three of these drugs inhibit carbonic
anhydrase
Primary use: to maintain urine flow in times
of hypoperfusion
◦ For clients with acute renal failure or during
prolonged surgery
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Pharmacological management of renal failure
and diuretic therapy
◦ Careful monitoring of client’s condition
◦ Providing education relating to prescribed drug
management
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Obtaining medical, drug, dietary, and lifestyle
history
Assessment of client’s weight, intake/output,
skin turgor/moisture, vital signs, breath
sounds, and presence of edema
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Obtain baseline and monitor periodically lab
values, weight, current level of urine output
Measure electrolytes, especially potassium,
sodium, and chloride, prior to loop-diuretic
therapy
Monitor blood urea nitrogen (BUN), serum
creatinine, uric acid, blood-glucose levels
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Increased potassium loss may occur when
used with digoxin
Increased risk of lithium toxicity when taking
thiazide diuretics
Allergies to sulfa-based medications can
indicate hypersensitivity
Use with caution in pregnant women
DO not administer to lactating women
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Teach client to
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Use sunscreen to decrease photosensitivity
Take potassium supplements, if ordered
Consume potassium-rich foods
Report any tenderness or pain in joints
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Advantage: client will not experience
hypokalemia
Critical to assess electrolytes (potassium and
sodium), blood urea nitrogen (BUN), serum
creatinine
Adverse effects : hyperkalemia, and GI
bleeding, confusion, dizziness, muscle
weakness, blurred vision, impotence,
amenorrhea, gynecomastia
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Spironolactone may decrease effectiveness of
anticoagulants
Clients taking lithium or digoxin may be at
increased risk for toxicity
Triamterene contraindicated for lactating
women
Report signs and symptoms of hyperkalemia
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Avoid use of potassium-based salt
substitutes
When in direct sunlight use sunscreen
Avoid performing tasks that require mental
alertness
Do not eat excess amount of foods high in
potassium
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Prototype drug: furesomide (Lasix); increases
urine output even when blood flow to kidney
is diminished
Mechanism of action : to block reabsorption
of sodium in Loop of Henle
Primary use: to treat hypertension and reduce
edema associated with heart failure, hepatic
cirrhosis, and renal failure
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Adverse effects: rapid excretion of large
amounts of water, dehydration and
electrolyte imbalances ototoxicity
Other examples
◦ Torsemide: longer half life than furosemide; oncea- day dosing
◦ Bumetanide (Bumex): 40 times potency of
furosemide; shorter duration of action
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Prototype drug: chlorothiazide (Diuril)
Mechanism of action: to block sodium
absorption in distal tubule of nephron
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Primary use: to treat mild to moderate
hypertension
◦ To treat severe hypertension, in combination with
other drugs
◦ To treat fluid retention from heart failure, liver
disease, corticosteroid or estrogen therapy
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Adverse effects: dehydration, orthostatic
hypotension, hypokalemia
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Less effective than loop diuretics but help
prevent hypokalemia
Prototype drug : spironolactone (Aldactone)
Mechanism of action: to block action of
aldosterone
Primary use: to significantly reduce mortality
in heart failure
Adverse effects: hyperkalemia
Click here to view an animation on the topic of spironolactone.
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Example: acetazolamide (Diamox)
Mechanism of action: to inhibit formation of
carbonic acid
Primary use: to decrease intraocular fluid
pressure in clients with glaucoma
Adverse effects: allergic reaction (contain
sulfa), fluid and electrolyte imbalances
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Example : mannitol
Mechanism of action: to quickly reduce
plasma volume
Primary use: to reduce intracranial pressure
due to cerebral edema
Also used to maintain urine flow in prolonged
surgery, acute renal failure, or severe renal
hypoperfusion
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Adverse effects:
◦ Headache, dizziness, tremors, dry mouth
◦ Fluid and electrolyte imbalances, thrombophlebitis
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Evaluation the patient
◦ Experiences a decrease in blood pressure.
◦ Is free from, or experiences minimal adverse
effects.
◦ Verbalizes an understanding of the drug’s use,
adverse effects and required precautions
◦ Demonstrates proper self-administration of the
medication (e.g., dose, timing, when to notify
provider).
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What are some good dietary sources of
potassium?
If a client is on Aldactone, what would you tell
them about high potassium foods?
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Assessments to make
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Teaching to include:
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Drugs include
◦ Antibiotics
 Fosfomycin (Monurol)
 Quinolones : cinoxacin, nalidixic
acid, norfloxacin
 Methenamine madelate
 Nitrofurantoin
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Fosfomycin (Monurol)
◦ Inhibits bacterial cell wall synthesis
◦ Reduces adherence of bacteria to epithelial cells
of urinary tract
◦ Single dose therapy
SE to expect:
◦ nausea, diarrhea, abdominal cramps, flatulence
SE to report:
◦ perineal burning, dysuria
 Indicates UTI is not responding to treatment
Drug interactions
◦ Drugs such as metoclopramide that increase GI
motility
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Norfloxacin (Noroxin) has wide range of activity
against gram negative and gram positive bacteria
 Expensive
 Reserve for resistant/recurrent infections
SE to report
◦ Hematuria as crystals can form in urinary tract
◦ HA, tinnitus, dizziness, tingling sensations,
photophobia
Various drug interactions can occur
◦ Assess client’s current drug therapy, monograph
of quinolone being used
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◦ Converts to ammonia and formaldehyde in acidic urine
◦ Used in clients susceptible to chronic, recurrent UTIs
◦ Preexisting infections treated with antibiotics
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Implementation
◦ DO NOT crush the tablets
◦ pH testing of urine: report over 5.5
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SE to expect
◦ N/V, belching
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SE to report
◦ Hives, pruritus, rash
◦ Bladder irritation, dysuria, frequency
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Drug interactions
◦ Acetazolamide, sodium bicarbonate
◦ Sulfamethizole
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◦ Interferes with several bacterial enzyme systems
◦ Effective only in the urinary tract
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SE to expect:
◦ N/V, anorexia, urine discoloration
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SE to report:
◦ Dyspnea, chills, fever, erythematous rash, pruritus
◦ Peripheral neuropathies
◦ Second infection
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Drug interactions
◦ Magnesium containing products can decrease
absorption
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Bethanecole chloride (Urecholine)
 Neostigmine (Prostigmin)
 Oxybutynin chloride (Ditropan)
 Phenazopyridine (Pyridium)
 Tolterodine (Detrol)
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◦ Parasympathetic nerve stimulant
◦ Causes contraction of detrusor urinae muscle
 Results in urination
 May also stimulate gastric motility
 Can increase gastric tone
 Can restore impaired rhythmic peristalsis
SE to expect
◦ Flushing of skin, HA
SE to report
◦ N/V, sweating, colicky pain, abdominal cramps
◦ Diarrhea, belching, involuntary defecation
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◦ Anticholinesterase agent
◦ Binds to cholinesterase
 Prevents destruction of acetylcholine
 Effects are: miosis; increased tone of
intestinal, skeletal, and bladder muscles
 Bradycardia; stimulation of secretions of
salivary and sweat glands
 Constriction of bronchi and ureters
Neostigmine used to prevent and treat
postoperative distension and urinary retention
◦ Assess for pregnancy, intestinal or urinary
obstruction, peritonitis
◦ Assess coronary status
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Antispasmodic agent—acts directly on
smooth muscle of the bladder
◦ Delays initial urge to void
◦ Do not use if glaucoma, myasthenia
gravis, ulcerative colitis, obstructive
uropathy
SE to expect
◦ Dry mouth, urinary hesitance, retention
◦ Constipation, bloating
◦ Blurred vision
 Report any SE that are intensified
92
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Produces local anesthetic effect in urinary
tract
Acts about 30 min. after administration
Used to relieve burning, pain, urgency,
frequency in UTI
Reduces bladder spasms
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SE to expect
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◦ Reddish-orange urine color
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SE to report
◦ Yellow sclera or skin
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Muscarinic receptor antagonists
Inhibit muscarinic action of acetylcholine on
bladder smooth muscle
Used to treat overactive bladder
Do not use if glaucoma, ulcerative colitis,
obstructive uropathy
S/E to expect
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Dry mouth
Urinary hesitance, retention
Constipation, bloating
Blurred vision
Report if the effects intensified
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Objective 18: Discuss patient
education guidelines for drugs that
affect the urinary system
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Objective 19: identify at least one nursing
diagnosis that may be applicable for clients
receiving diuretic therapy under the guidance
of the instructor
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