Renal pharmacology

Question 1

Mannitol

Answer 1

• Mechanism: Osmotic diuretic
  
  • Increased tubular fluid osmolarity
  • produces increased urine outflow
  • Acts on the proximal tubule
• Use:
  
  • shock
  • drug overdose
  • increased intracranial/intraocular pressure
• Toxicity: Pulmonary edema, dehydration
• Contraindicated in anuria and CHF

Question 2

Acetazolamide

Answer 2

-Mechanism: Carbonic anhydrase inhibitor
-Self limited NaHCO3 diuresis
-Reduction in total HCO3- stores
-Acts at proximal tubule
Uses:
-Glaucoma
-Urinary alkalinization
-Metabolic alkalosis
-Altitude sickness
-Toxicity:
-Hypercholremic metabolic acidosis
-Neuropathy
-NH3 toxicity
-Sulfa allergy

Question 3

Furosemide

Answer 3

• Mechanism: Sulfonamide loop diuretic
  
  • Inhibits Na+/K+/2Cl- cotransporter of TAL
  • Abolishes medulla hypertonicity
  • Prevents concentration of the urine
  • Stimulates PGE release (vasodilates afferent arteriole)
  • Inhibited by NSAIDs
  • Increases Ca2+ secretion
• Uses:
  
  • Edematous state (CHF, cirrhosis, nephrotic syndrome)
  • HTN
  • Hypercalcemia
• Toxicity:
  
  • Ototoxicity
  • Hypokalemia
  • Dehydration
  • Allergy to sulfa
  • Nephritis
  • Gout

Question 4

Ethacrynic Acid

Answer 4

• Mechanism: Phenoxyacetic acid loop diuretic
  
  • Not a sulfonamide
  • -Inhibits Na+/K+/2Cl- cotransporter of TAL
  • Abolishes medulla hypertonicity
  • Prevents concentration of the urine
  • Stimulates PGE release (vasodilates afferent arteriole)
  • Inhibited by NSAIDs
  • Increases Ca2+ secretion
• Uses: Diuresis in patients allergic to sulfa drugs
• Toxicity: Same as furosemide

Question 5

Hydrachlorothiazide

Answer 5

• Mechanism: Thiazide diuretic
  
  • NaCl reabsorption in early distal tubule
  • Reduces diluting capacity of nephron
  • Decreases Ca2+ excretion
• Uses:
  
  • HTN
  • CHF
  • idiopathic hypercalciuria
  • Nephrogenic diabetes insipidus
• Toxicity:
  
  • Hypokalemic metabolic alkalosis
  • Hyponatremia
  • hyperglycemia
  • hyperlipidemia
  • hyperuricemia
  • hypercalcemia
  • Sulfa allergy

Question 6

Spironolactone

Answer 6

• Mechanism: competitive aldosterone receptor antagonist
  
  • Act in cortical collecting tubule
• Uses:
  
  • hyperaldosteronism
  • K+ depletion
  • CHF
• Toxicity:
  
  • Hyperkalemia can lead to arrhythmias
  • Endocrine effects: gynecomastia & antiandrogen effects

Question 7

Triamterene

Answer 7

• Same as Amiloride
• Mechanism: Block Na+ channels in CCT
• Uses:
  
  • hyperaldosteronism
  • K+ depletion
  • CHF
• Toxicity:
  
  • Hyperkalemia can lead to arrhythmias