Diuretics Flashcards
What is the target response of diuretics?
Increase urine volume by increasing excretion of Na+ (solutes) and H2O (inhibiting reabsorption)
What is Natriuresis?
Increasing excretion of Na+ from the body.
What are the principle uses of diuretics?
- Treatment of Edema (excreting water)
- Treatment of Mild Essential Hypertension
Where is the main site of Na+/ H20 reabsorption in the nephron?
-The Proximal Convoluted Tubule (65%)
Examples of Carbonic Anhydrase Inhibitors and their mechanism of action?
- Acetazolamide
- Inhibits Carbonic Anhydrase enzyme action
- ->Increases excretion of NaHCO3 and K+.
- ->Retention of H+ ions.
- ->Hypokalemia of PCT
What are the Therapeutic Uses of Carbonic Anhydrase Inhibitors?
- Glaucoma, petit mal (absence/ small) seizures
- *Acute high altitude mountain sickness
- ->Promotes metabolic acidosis due to accumulation of H+ which increases respiration?
- Can treat edema and metabolic alkalosis
What are the adverse effects of Carbonic Anhydrase Inhibitors?
- Metabolic acidosis (due to the excretion of bicarbonate and retention of H+)
- Hypokalemia (due to the excretion of K+)
- Hypersensitivity reactions
True of False:
Osmolairty increases along the descending loop of Henle.
True.
–>At the bottom of the descending loop of Henle, Na+ concentration is 3x higher than the top portion.
Mannitol
Osmotic Diuretic
–>Causes a high amount of water excretion and minimal solute loss in the Thin Descending loop of Henle.
(Promotes diuresis and little natriuresis)
-Used to treat cerebral edema (decrease intracranial pressure) and acute renal failure (promote urine formation)
Adverse Affects: Dehydration in long term use.
What is characteristic of the Thin Descending loop of Henle?
-NO electrolyte loss.
Aquaporins channels allow for water movement only
What is characteristic of the Thick Ascending loop of Henle?
- Impermeability to water
- ->Electrolyte movement only.
- Major site of salt reabsorption
Mechanism of Action of Loop Diuretics?
-Blocks the Na+/ K+/ 2Cl- Pump (Inhibits exchanger) in the Thick Ascending loop of Henle
- Drugs include Furosemide, Bumetanide, Torsemide and Ethacrynic Acid
- Rapid onsets
- ->Increased secretion of Na+/ K+/ Cl- and Ca2+
Therapeutic uses?
- Edema due to increased secretion of solutes and increased retention of H2O.
- -Adverse Effects include hypokalemia, hyponatremia, hypovolemia, alkalosis, ototoxicity, hypotension and hyperuricemia.
What drugs affect the Distal Convoluted Tubule, and what is their mechanism of action?
- ->Thiazides!
- Inhibits Na+/ Cl- pump to increase SECRETION of Na+, Cl-, K+ and H+
- ->Increases Ca2+ reabsorption
Examples of thiazides include:
-Hydrocholorthiazide (HCTZ)
(Chlorothalidone Indapamine)
Therapeutic uses include:
- Essential hypertension
- Treatment for hypocalcemia
Adverse Effects include: Hyperkalemia, hypercalcemia, hyperuricemia, alkalosis and impaired glucose tolerance.
What are the two mechanism’s of action of K+ Sparing Diuretics, where do they act on the nephron and what drugs are included in this category?
Act on the cortical collecting tubule.
1) Aldosterone receptor antagonists (blocks K+ excretion/ H+ excretion)
- Spironolactone and Eplerenone
2) ENa+C Inhibitors (Blocks H+/ Na+/K+ excretion)
- Triamerene and Amilorde
Therapeutic uses:
Spironolactone is frequently used in combination with Furosemide (Loop Diuretic) to reduce hypokalemia in patients with hypertension or heart disease.
Adverse Effects include hyperkalemia and acidosis.
Spironolactone:
- K+ Sparing Diuretic
- ->Aldosterone receptor antagonist
- MILD androgen blocker (can cause gynecomastia) and menstrual irregularities.
- Can be used to treat Hirsutism (hair growth on women’s faces)