Diuretic Drugs Flashcards
Describe Mechanism of Carbonic Anhydrase Inhibitors
These drugs decrease the ability to exchange Na+ for H+ resulting in mild diuresis. Note there is only a weak effect on Na+ retention because downstream, Loop of Henle reabsorbs a large fraction of NaCl.
What type of drug is Acetazolamide? What mechanism does it work by? What are it’s uses?
It is a diuretic that works via Carbonic Anhydrase Inhibition. Carbonic Anhydrase works normally in the proximal tubular epithelial cells to catalyse production of H+ and carbonate. (H+ anti ported with Na_) (Carbonate used for pH balance) Acetazolamide is mainly used for non-diuretic uses b/c it’s only a mild diuretic. Used to treat chronic glaucoma and prophylaxis of acute altitude sickness.
Describe mechanism of Loop Diuretics? (AKA High ceiling diuretics).
work on the ascending loop of henle by inhibiting the Na+/K+/2Cl carrier in the luminal membrane. These are the most effective diuretic b/c ascending limb accounts for 25% of filtered NaCl.
What are the therapeutic uses of Loop Diuretics?
These diuretics can be used in 1) Oedema of congestive heart failure. 2) Hypercalcemia 3) reducing intracranial pressure in an emergency
What are the therapeutic uses of Loop Diuretics?
These diuretics can be used in 1) Oedema of congestive heart failure. 2) Hypercalcemia 3) reducing intracranial pressure in an emergency They are excellent for immediate use.
Adverse Effects of Loop Diuretics
1) potassium depeltion - hypokalemia - due to the heavy load of Na+ presented to the detail tubule 2) acute hypovolemia- can cause severe loss of blood volume and potentially shock/cardiac arrhythmias. 3) hyperuricemia - block uric acid secretion causing attacks of gout 4) Rarely you’ll see hearing damage (ototoxicity)
Describe mechanism of thiazide diuretics
Act on distal tubule to decrease the reabsorption of Na+ by binding tot he Cl- site of the Na+/Cl- cotransporter.- inhibiting it’s action. This results in increased concentration of Na+ and Cl- in tubular fluid.
What type of drug is Chlorothiazide and by what mechanism does it work? Any Adverse side effects?
It is a Thiazide diuretic - which causes increased excretion of Na+ and Cl- with a net loss of K+. This drug over time could cause peripheral vascular resistance caused by relaxation of arteriolar smooth muscle. Side effects include potassium depletion, hyperuricemia, volume depletion, hypercalcemia, hyperglycaemia and rare hypersensitivity.
Describe the mechanism of Potassium-sparing Diuretics,
These diuretics act in the distal collecting tubule to inhibit Na+ reabsorption, K+ secretion, and H+ secretion. Major use is in treatment of hypertension - used in combination with a thiazide. ex) Amiloride
What type of drug is Amiloride?By what mechanism does it work? Any adverse Side effects?
Amilloride is a potassium sparing diuretic. It acts on the late distal tubule and collecting duct by blocking the luminal Na Channels independently to aldosterone- it inhibits Na+ reabsorption and reduces K+ and H+ secretion . It may produce hyperkalemia
Describe the mechanism of Osmotic Diuretics
These are pharmacologically inert substances that are filtered by the glomerulus, but can’t be reabsorbed. They act by indirectly modifying the content of the filtrate by increasing the osmolarity - water is then retained in the urine to maintain the osmotic balance resulting in increased urinary output with a small amount of Na+ excretion.
Which Diuretic class is the most effective?
20-30% increase in Na+ excretion for potent loop diuretics. 10% for Thiazides and 2-3% for potassium sparing diuretics.
Describe where each class of diuretics acts in the nephron
