NURS 1950: Pharmacology
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Kidneys regulate◦ Fluid volume, electrolytes, acid-base balance
Kidneys secrete◦ Renin- for blood-pressure regulation◦ Erythropoietin – to stimulate blood-cell production◦ Calcitrol –active form of vitamin D for bone
hemeostasis
Urinary system consists of◦ Two kidneys◦ Two ureters◦ One bladder◦ One urethra
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
Filtrate passes through loop of Henle, then distal tubule
Filtrate empties into collecting ducts and leaves nephron as urine
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
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
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
Urinalysis Serum creatinine Diagnostic imaging Renal biopsy
Glomerular filtration rate (GFR)◦ Best marker for estimating renal function◦ Measure volume of water filtered per minute
Requires immediate treatment Accumulation of waste products can be fatal Most common cause is hypoperfusion
Cause must be rapidly identified◦ Heart failure ◦ Dysrhythmias◦ Hemorrhage◦ Dehydration
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
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
Objective 4: pituitary hormone that influences urine volume:◦ ADH (Posterior pituitary)
Objective 5: adrenocortical hormone that influences urine volume:◦ Aldosterone (increases Na+ reabsorption in the
distal tubule)
Objective 6: four ways fluid is lost from the body◦ Urine, perspiration, lungs, stool
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Objective 7: describe the actions of diuretics
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Diuretics act to
Deplete blood volume
Excrete sodium
Vasodilate peripheral arterioles (how is unknown)
Increase rate of urine flow Excretion of excess fluid used to treat
◦ Hypertension, heart failure, kidney failure◦ Liver failure or cirrhosis, pulmonary edema
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 hoursDuration 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
Cross sensitivities◦ Sulfonamides and Lasix, Demadex
SE to expect◦ Oral irritation◦ Dry mouth◦ Orthostatic hypotension
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SE to report with loop diuretics◦ 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
Obtain baseline and monitor periodically lab values, weight, current level of urine output
Monitor electrolytes, especially potassium, sodium, and chloride
Monitor blood urea nitrogen (BUN), serum creatinine, uric acid, and blood-glucose levels
Assess for circulatory collapse, dysrhythmias, hearing loss, renal failure, and anemia
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
Clients should take potassium supplements, if ordered, and consume potassium–rich foods
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
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,
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
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
Pharmacological management of renal failure and diuretic therapy◦ Careful monitoring of client’s condition◦ Providing education relating to prescribed drug
management
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
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
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
Teach client to◦ Use sunscreen to decrease photosensitivity◦ Take potassium supplements, if ordered◦ Consume potassium-rich foods◦ Report any tenderness or pain in joints
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
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
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
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
• Adverse effects: rapid excretion of large amounts of water, dehydration and electrolyte imbalances ototoxicity
Other examples◦ Torsemide: longer half life than furosemide; once-
a- day dosing◦ Bumetanide (Bumex): 40 times potency of
furosemide; shorter duration of action
Prototype drug: chlorothiazide (Diuril) Mechanism of action: to block sodium
absorption in distal tubule of nephron
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 Adverse effects: dehydration, orthostatic
hypotension, hypokalemia
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.
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
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
Adverse effects:◦ Headache, dizziness, tremors, dry mouth◦ Fluid and electrolyte imbalances,
thrombophlebitis
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).
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
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
Implementation ◦ DO NOT crush the tablets◦ pH testing of urine: report over 5.5
SE to expect ◦ N/V, belching
SE to report◦ Hives, pruritus, rash◦ Bladder irritation, dysuria, frequency
Drug interactions◦ Acetazolamide, sodium bicarbonate◦ Sulfamethizole
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◦ Interferes with several bacterial enzyme systems◦ Effective only in the urinary tract
SE to expect: ◦ N/V, anorexia, urine discoloration
SE to report:◦ Dyspnea, chills, fever, erythematous rash, pruritus◦ Peripheral neuropathies ◦ Second infection
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
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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
SE to expect◦ Reddish-orange urine color
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
◦ 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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