Diuretics

Question 1

Furosemide (Lasix): Most frequently prescribed loop diuretic

Answer 1

• Mechanism of action
• ActsonascendingloopofHenletoblockreabsorption
• Pharmacokinetics
• Rapidonset(PO60min;IV5min)
• Therapeutic uses
• Pulmonaryedema • Edematousstates • Hypertension
• Adverse effects
• Hyponatremia, hypochloremia, and dehydration
• Hypotension
• Lossofvolume
• Relaxationofvenoussmoothmuscle • Hypokalemia
• Ototoxicity
• Adverse effects
• Hyperglycemia
• Hyperuricemia
• Use in pregnancy
• Impact on lipids, calcium, and magnesium

Drug interactions • Digoxin
• Ototoxic drugs
• Potassium-sparing diuretics
• Lithium-lowers sodium.
• Antihypertensive agents
• Nonsteroidal antiinflammatory drugs-increases effects of lasix.
• Preparations, dosage, and administration • Oral
• Parenteral

Question 2

Other High-Ceiling (Loop) Diuretics

Answer 2

Ethacrynic acid [Edecrin] • Bumetanide [Bumex]
• Torsemide [Demadex]
• All can cause:
• Ototoxicity, hypovolemia, hypotension, hypokalemia, hyperuricemia, hyperglycemia, and disruption of lipid metabolism

Question 3

Thiazides and Related Diuretics

Answer 3

• Also known as benzothiadiazides
• Effects similar to those of loop diuretics
• Increase renal excretion of sodium, chloride, potassium, and water
• Elevate levels of uric acid and glucose
• Maximum diuresis is considerably lower than
with loop diuretics
• Not effective when urine flow is scant (unlike with loop diuretics)

Question 4

Hydrochlorothiazide [HydroDIURIL]

Answer 4

• Most widely used
• Action: Early segment distal convoluted tubule
• Peaks in 4 to 6 hours
• Therapeutic uses
• Essentialhypertension
• Edema
• PostmenapausalOsteoporosis-It helps with reabsorption of calcium.

• Adverse effects
• Hyponatremia, hypochloremia, and dehydration
• Hypokalemia
• Use in pregnancy and lactation
• Hyperglycemia
• Hyperuricemia
• Impact on lipids, calcium, and magnesium
NO OTOTOXICITY.

• Drug interactions
• Digoxin
• Augments effects of hypertensive medications
• Can reduce renal excretion of lithium (leading to
accumulation)
• NSAIDs may blunt diuretic effect
• Can be combined with ototoxic agents without increased risk of hearing loss

Question 5

Potassium-Sparing Diuretics

Answer 5

Useful responses
• Modest increase in urine production
• Substantial decrease in potassium excretion
• Rarely used alone for therapy • Aldosterone antagonist
• Spironolactone
• Nonaldosterone antagonists • Triamterene
• Amiloride

Question 6

Spironolactone [Aldactone]

Answer 6

• Mechanism of action
• Blocks aldosterone in the distal nephron
• Retention of potassium
• Increased excretion of sodium
• Therapeutic uses • Hypertension
• Edematous states
• Heart failure (decreases mortality in severe failure) • Primary hyperaldosteronism
• Premenstrual syndrome
• Polycystic ovary syndrome
• Acne in young women
• Adverse effects • Hyperkalemia
• Benign and malignant tumors • Endocrine effects
• Drug interactions
• Thiazide and loop diuretics
• Agents that raise potassium levels

Question 7

Triamterene [Dyrenium]

Answer 7

Potassium sparing diuretic

 Mechanism of action
• Disrupts sodium-potassium exchange in the distal
nephron
• Direct inhibitor of the exchange mechanism
• Decreases sodium reuptake
• Inhibits ion transport
• Therapeutic uses • Hypertension
• Edema

• Adverse effects • Hyperkalemia
• Leg cramps • Nausea
• Vomiting
• Dizziness
• Blood dyscrasias (rare)

Question 8

Amiloride [Midamor]

Answer 8

Potassium Sparing Diuretic

• Mechanism of action
• Blocks sodium-potassium exchange in the distal
nephron
• Therapeutic use
• Counteracts potassium loss caused by more powerful diuretics
• Adverse effects • Hyperkalemia
• Drug interaction
• ACE inhibitors; other drugs with hyperkalemia

Question 9

Osmotic Diuretic

Mannitol [Osmitrol]

Answer 9

• Promotes diuresis by creating osmotic force within
lumen of the nephron • Pharmacokinetics
• Drugmustbegivenparenterally • Therapeutic uses
• Prophylaxisofrenalfailure
• Reductionofintracranialpressure • Reductionofintraocularpressure

• Adverse effects • Edema
• Headache
• Nausea
• Vomiting
• Fluid and electrolyte imbalance