HTN, CHF, acute pulmonary edema, renal failure, hyperkalemia, chemical intoxication.
True or False
Furosemide does not contain a sulfonamide functional group.
False.
How is furosemide eliminated from the body?
88% Renal (secretion)
12% Fecal
What is the target MOA of furosemide? Where is its site of action in the nephron?
Inhibits the Na/K/2Cl cotransporter.
Thick ascending loop of henle.
What will happen to urine levels of the following:
H2O, NaCl, Ca, Mg, K
Increase: H2O, NaCl, Ca, Mg, K
What happens to GFR when using furosemide? Why?
Although you would expect GFR to decrease since the site of action is before the macula densa, the macula densa senses NaCl levels in the urine by using the Na/K/2Cl transporter. Since it is inhibited by furosemide, the macula densa "thinks" the nephron is not filtering enough fluid, and GFR is increased as renin is released.
Why can furosemide lead to increased calcium excretion?
At this site in the nephron, K is shuttled out of the cell to repel Ca into the cell. However, as K is lost due to the drug, Ca is not reabsorbed.
What is the capacity / relative strength of furosemide as a diuretic?
Capacity: 25% filtered NaCl, 40% filtered K
Strength: relatively strong given the site of action
What are some adverse effects associated with furosemide?
Hypokalemia
Hyperuricemia
Ototoxicity (Na/K/2Cl sympoter located in apparatus of inner ear) --> reversible
