Diuretics Flashcards
Thiazide diuretics (increase/decrease) calcium reabsorption
Increase
Loop diuretics (increase/decrease) calcium and magnesium excretion
Increase
What effect do acidic drugs have on uric acid excretion?
They compete for excretion with uric acid, so they may cause hyperuricemia —> gout
What are the 3 Carbonic Anhydrase Inhibitors?
Acetazolamide (Diamox)
Dorzolamide (Trusopt) eyedrop
Brinzolamide (Azopt) eyedrop
What is the MOA of Carbonic Anhydrase Inhibitors?
- Block Carbonic Anhydrase enzyme
- Prevents production of bicarb
- H+ can’t exchange with Na+ in the urine so more Na+ and H2O are lost in the urine
What are the 3 indications for Carbonic Anhydrase Inhibitors?
- Glaucoma- decreases aqueous humor and CSF
- Alkalinization of the urine (more bicarb in urine)
- Alkalosis (metabolic and respiratory/Acute Mountain Sickness)
(WOW WHY ISN’T HTN OR EDEMA ON HERE????? ISNT THIS THE DIURETIC LECTURE!!??)
How long do Carbonic Anhydrase Inhibitors work as diuretics?
Only a few days
Reason we don’t use it as a diuretic
Weak bases are (more/less) ionized in alkaline environments
Less ionized.
Which makes it easier for them to diffuse across membranes
What are the adverse effects of Carbonic Anhydrase Inhibitors?
Hyperchloremic Metabolic Acidosis
Hypokalemia
Hyperuricemia
Why do CA Inhibitors cause hyperchloremic metabolic acidosis?
The Na+ loss is in the form of NaHCO3, not NaCl.
=you’re losing bicarb
Why do CA inhibitors cause hypokalemia?
More Na+ is in the lumen which causes an increased Na/K exchange further down the line
Why do CA inhibitors cause hyperuricemia?
They are acids and compete for uric acid secretion
What are the 4 Loop Diuretics?
Furosemide (Lasix)
Bumetanide
Torsemide
Ethacrynic Acid
What is the MOA of Loop Diuretics?
- Block NKCC2 cotransporter
- Induce kidney prostaglandins which decreases salt reabsorption
- Vasodilation- due to the prostaglandins
What are the indications for Loop Diuretics?
Heart Failure
Pulmonary Edema
Peripheral Edema
Hypercalcemia
How do loop diuretics relieve pulmonary congestion?
By increasing systemic venous capacitance
NOT because of fluid loss!!!**
What are the adverse effects of loop diuretics?
Hypokalemic metabolic alkalosis (induces K+ and H+ loss)
Hypocalcemia and hypomagnesemia
Hyperuricemia (loops are acids)
Irreversible ototoxicity**
Which loop diuretic is the worst at causing ototoxicity?
Ethacrynic acid**
What other drug will make the ototoxicity of loop diuretics even worse?
Aminoglycosides
Streptomycin, tobramycin, neomycin, amikacin, gentamycin in case you forgot
Which loop diuretic is NOT a sulfonamide and is OK for patients with Sulfa allergies?
Ethacrynic acid***
What other drug should not be combined with loop diuretics due to the risk of fatal hypokalemia?
Digoxin
What makes ethacrynic acid (Edecrin) different from the other loop diuretics?
It is not a sulfonamide derivative
It has the highest risk of ototoxicity
*100% chance this is on the test
Your patient has profound edema and your choices are Lasix and Ethacrynic Acid. Which one should you use?
Use lasix unless he has a sulfa allergy
What are the 2 thiazides and the 4 compounds released to thiazides?
Thiazides:
Hydrochlorothiazide
Chlorothiazides
Related compounds: Chlorthalidone Metolazone Quinethazone Indapamide
(You have to know the related compounds too)
What is the MOA of thiazide diuretics?
Inhibition of sodium reabsorption at the early distal tubule.
Also increases ATP-dependent K+ channel opening which hyperpolarizes membranes=vasodilation (as well as decreased insulin release because these K+ channels are in the pancreas too)