Renal Pharm Flashcards
Applications of mannitol
- Reduce ICP and/or IOP
- Flush out renal toxins (i.e. myoglobin) and protect kidneys
Electrolyte imbalances associated w/ mannitol use
- Inital hyponatremia
- Followed by hypernatremia and hypkalemia
What enzyme converts CO2 and H2O back into carbonic acid once inside the cells of the proximal tubule?
Carbonic anhydrase type II
Acetazolamide inhibits this preventing bicarb reabsorption
The bicarbonate is transported into the
blood along with sodium (Na⁺), while hydrogen is secreted back into the tubule in exchange for
more sodium.
What are the general effects of acetazolamide
- Increase excretion of bicarb, sodium, and water - leading to mild increase in urine output
- Decrease in bicarb serum cause metabolic acidosis
Clinical uses of acetazolamide
- Edematous conditions w/ alkalosis
- Kidney stone prevention
- Acute elevation sickness
- Sleep apnea
- Glaucoma
- CSF leakage
Adverse effects of acetazolamide use
- MA
- Hyperchloremia
- Kidney stones
- Hypokalemia
- Neurological effects (drowsiness and paresthesia)
Mechanism of carbonic anhydrase in the eye
Carbonic anhydrase in the ciliary body helps produce aqueous humor.
Inhibiting this enzyme reduces fluid production and lowers eye pressure, which is useful in glaucoma
Mechanism of carbonic anhydrase in the brain
Carbonic anhydrase in the choroid plexus helps produce CSF
Inhibition reduces CSF production, which is useful for conditions like CSF leakage
MOA of loop diuretics
Block NKCC cotransporter in thick ascending limb of the loop of Henle
Results in increased excretion of Na/K/Cl/Ca/Mg and water
Effect of loop diuretic on prostaglandin release
Loop diuretics stimulate prostaglandin production - dilates afferent arteriole, increasing GFR and RBF
Loop diuretics are used to Tx what electrolyte imbalance(s)
Hypercalcemia
Hyperkalemia
Increasing excretion of these ions
Loop diuretics can be used to treat what toxic exposures?
Halide poisining
Adverse effects of loop diuretics
- Hypokalemic metabolic acidosis
- Hypomagnesemia and hypocalcemia
- Hyperuricemia
- Ototoxicity
- Hyperglycemia
- May trigger allergic response in sulfa-sensitive patients (ethacrynic acid can be used in these cases)
Thiazides share the same secretion system used by what?
Uric acid - competes with its secretion and can raise uric acid levels
Thiazide MOA
Acts mainly on the NCC of the DCT
Like sulfonamide medications, thiazides can cause allergic reactions, so patients with sulfa allergies should use caution
List examples of K-sparing diuretics
- Spironolactone
- Amiloride
- Eplerenone
- Triamterene
MOA of K-sparing diuretics
Act on the cortical collecting tubules in the kidney
What are the role of principal cells in the collecting ducts?
- Epithelial sodium channels (ENaC) allow sodium to enter the cell from the tubule.
- ATP-dependent potassium channels move potassium into the tubule.
- Express V2 receptors to bind ADH
Role of α-Intercalated Cells in the collecting ducts?
These cells are responsible for secreting hydrogen ions (H⁺) into the tubule to regulate blood pH.
They use two transporters:
- H⁺ ATPase pumps hydrogen ions into the tubule.
- H⁺/K⁺ ATPase pumps hydrogen ions into the tubule in exchange for potassium
What types of Rx’s are tolvaptan and conivaptan?
ADH antagonists
Tolvaptan - po
Conivaptan - IV
When ADH binds V2 receptors, increased ______ leads to aquaporin transportation to the cell membrane
When ADH binds V2 receptors, increased cAMP leads to aquaporin transportation to the cell membrane
Which of the following is most likely to be used to treat calcium oxalate bladder stones that are recurrent?
A. Acetazolamide
B. Furosemide
C. HCTZ
D. Mannitol
C. HCTZ
When used chronically, hydrochlorothiazide is LEAST likely to cause which of the following:
A. Decreased urinary excretion of calcium
B. Elevated blood cholesterol
C. Elevated blood glucose
D. Elevated uric acid
E. Irreversible ototoxicity
E. Irreversible ototoxicity
Hypocalciuria is associated with what class of diuretics?
Thiazides
Why they’re used to prevent kidney stones (calcium stones)
A patient complains of paresthesias associated with one of her drugs. She is found to have hyperchloremic metabolic acidosis. She is probably taking:
Acetazolamide
A drug that increases the formation of dilute urine in water-loaded subjects and is used to treat SIADH is:
Conivaptan
A drug that is useful when there is concern about high altitude sickness is:
Acetazolamide
Where in the cell do potassium sparing diuretics bind its receptor?
In the cytoplasm (aldosterone receptor is in the cytoplasm)
What diuretic is associated w/ hyperchloremic metabolic acidosis?
Carbonic anhydrase inhibitors
- Hyperkalemia
- Blockade
- Reduced expression of Na/K pumps
Spironolactone has androgen effects by antagonizing progesterone receptors too
Amilioride and triamterene antagonize what?
The ENaC channels of principal cells
Unlike other k-sparing diuretics (i.e. aldosterone antagonists)
What class of diuretics results in an increased excretion of Mg/Ca?
Loop diuretics
What class of diuretics lead to enhanced potassium excretion due to increased sodium delivery to the collecting duct?
Thiazides
Inhibition of the NCC symporter in the DCT increases sodium delivery to the collecting duct
