Drugs Affecting the Urinary
System
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Diuretics
• Functions to lower blood pressure by primarily reducing Na
reabsorption
• Remember: Where sodium goes water will follow
• Reduced Na reabsorption means that there is more Na in the
filtrate and therefore also more water
• Urine is more dilute
• Systemic Effect: lower blood volume and therefore decreased
blood pressure
• More useful for mild to moderate hypertension
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Thiazide Diuretics
• Blocks Na/Cl transporter in distal convoluted tubule
• Inhibit the transport of sodium by these cells
• The diminished sodium gradient in the medulla
interferes with the production of a concentrated
urine
• Larger amounts of a dilute urine are produced,
causing a loss of water from the body and a
decreased blood pressure
• Drug: Hydrochlorothiazide
• Most drugs in this class in in -thiazide
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Loop Diuretics
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Used for hypertension
Block Na/K/2Cl transporter in Loop of Henle
Similar action to thiazides but better efficacy
Better for severe hypertension
• Drug: Furosemide
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Osmotic Diuretics
• Any osmotically active agent that is filtered by the glomerulus
but not reabsorbed
• These agents will prevent water reabsorption in the PCT and
the descending limb of the Loop of Henle (normally these
areas are freely permeable to water)
• Urine is more dilute
• Mannitol is used as an osmotic diuretic
• Must be given IV to cause diuresis
• If given PO (by mouth), will cause diarrhea
• Glucose acts as an osmotic diuretic in patients with
hyperglycemia
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Diuretic: ADH Inhibitors
• Drugs such as alcohol inhibit ADH release from the posterior
pituitary
• Decreased water reabsorption
• More dilute urine
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Diuretic: Aldosterone Receptor
Blocker
• Block aldosterone receptor collecting ducts
• Therefore decrease sodium reabsorption
• Drugs in this class also decrease the amount of potassium
secreted
• More dilute urine; decreased blood volume
• Drug: Spironolactone
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Renin Inhibitor
• Used for hypertension
• Inhibits enzyme activity of renin (prevents renin from
converting angiotensinogen to angiotensin I)
• Reduces angiotensin I, angiotensin II and aldosterone
• Also effects ADH secretion (refer to RAAS diagram)
• Drug: Aliskiren
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Beta Receptor Blockers
• Typically used to lower blood pressure
• Drugs in this class block beta-adrenergic receptors of the
sympathetic nervous system
• Remember (from slide 69): Direct stimulation of granular cells by
sympathetic nervous system causes the release of renin
• Sympathetic nervous system acts on beta receptors
• Drugs in this class tend to end in –olol (Propanalol, Atenolol,
Pindolol)
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Beta- Receptor Blockers
• Propranolol
• Blocks beta receptors, therefore inhibiting the stimulation for
release of renin
• Depresses the RAAS
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Less Ang II
Less Na (and water) reabsorption
Less Aldosterone secretion from adrenal gland
Less ADH secretion from posterior pituitary
• More dilute urine
• Lower blood volume (and therefore lower blood pressure)
• Not all beta blockers will cause this
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Angiotensin-Converting Enzyme
(ACE) Inhibitors
• Drugs in this class inhibit ACE therefore preventing Ang I from
converting to Ang II
• Used to lower blood pressure
• Also help stabilize renal function by decreasing proteinuria
(protein in urine)
• Decrease efferent arteriolar resistance therefore decreasing
intraglomerular capillary pressure
• Adverse effects include acute renal failure and hyperkalemia
• Drugs in this class tend to end in –pril (captopril, enalapril,
benzapril)
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Angiotensin-Converting Enzyme
(ACE) Inhibitors
• Captopril
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Inhibits conversion of Ang I to Ang II
Less Na (and water) reabsorption
Less Aldosterone secretion from adrenal gland
Less ADH secretion from posterior pituitary
More dilute urine
Decreased blood volume (and therefore blood pressure)
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Angiotensin Receptor Blockers
(ARBs)
• Used to decrease blood pressure
• Block Ang II receptors therefore preventing the actions of Ang
II
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Less Na (and water) reabsorption
Less Aldosterone secretion from adrenal gland
Less ADH secretion from posterior pituitary
More dilute urine
Decreased blood volume (and therefore blood pressure)
• Drugs in this class tend to end in –sartan (losartan, valsartan,
candesartan)
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Non-Steroidal Anti-Inflammatory
Drugs (NSAIDs)
• Inhibit cyclooxygenase enzymes 1 and 2 (COX1 and COX2)
• COX enzymes needed to synthesize prostaglandins
• Prostaglandins  vasodilation
• AT THE GLOMERULAR LEVEL
• Inhibition of the vasodilatory effect leads to constriction of the
afferent arteriole
• Effect on GFR and renal perfusion pressure? _________________
• Leads to fluid retention
• Decrease in urinary waste products
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NSAIDs
• Examples:
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Ibuprofen
Napoxen
Indomethacin
Diclofenac
Meloxicam
Celecoxib
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