Diuretics Flashcards
1
Q
Carbonic anhydrase inhibitors
A
- Azetazolamide (oral), Dorzolamide and Brinzolamide (topical)
- Function site at proximal convoluted tubule; where 60-70% of total sodium are reabsorbed
- Used in glaucoma, acute mountain sickness, metabolic alkalosis
- Side effects: bicarbonaturia and metabolic acidosis, hypokalemia, hyperchloremia, paresthesiasis, renal stones, sulfonamide hypersensitivity
2
Q
Carbonic anhydrase inhibitors; mechanism of action
A
- Inhibit carbonic anhydrase in PCT;
1) CO2 + H20 –x–> H+ + HCO3
2) H2CO3 –x–> H20 + CO2
Cause: - Decreased H+ formation inside PCT cell
- Decreased Na+/H+ antiport
- Increased Na+ and HCO3 in lumen
- Increased diuresis; bicarbonaturia
3
Q
Loop diuretics
A
- Furosemide, Bumetanide, Torsemide (sulfonamide derivatives), Ethacrynic acid (phenoxyacetic acid derivative)
- Function site at thick ascending limb; where 20-30% of total sodium is reabsorbed
- Used in edematous states (pulmonary edema, ascitis), acute renal failure, anion overdose, hypercalcemic states, hypertension
- Side effects: Sulfonamide hypersensitivity, hypokalemia and alkalosis, hypocalcemia, hypomagnesemia, hyperuricemia, ototoxicity
4
Q
Loop diuretics; mechanism of action
A
- Inhibit Na+/K+/2Cl- transporter in TAL Cause: * Decreased K+ in TAL cell * Decreased back diffusion of K+ * Decreased positive potential * Decreased reabsorption of Ca2+ and Mg2+ * Increased Ca2+ excretion * Increased diereses; massive sodium chloride diuresis
5
Q
Thiazides
A
- Hydrochlorothiazide, Indapamide, Clopamide, Metolazone
- Function site at distal convoluted tubule; where 5-8% of total sodium is reabsorbed
- Used in hypertension, CHF, nephrolithiasis (calcium stones), nephrogenic diabetes insipidus
- Side effects; sulfonamide hypersensitivity, hypokalemia and alkalosis, hypercalcemia, hyperuricemia, hyperglycemia, hyperlipidemia
- Drug interaction: Digoxin causes increased toxicity due to electrolyte disturbances
6
Q
Thiazides; mechanism of action
A
- Inhibit Na+/Cl- transporter in DCT Cause: * Increased luminal Na+ and Cl- in DCT * Increased Ca2+ and Mg2+ reabsorption * Increased diuresis; sodium chloride diuresis
7
Q
Potassium sparing agents
A
- Spironolactone and Eplereone:
- Used in hyperaldosteronic state adjunct to K+ wasting diuretics, antiandrogenic uses, congestive heart failure.
- Used in combination with thiazides
- Side effects: hyperkalemia and acidosis
- Amiloride and Triamterene:
- Used adjunct to K+ wasting diuretics, lithium-induced, nephrogenic diabetes insipidus
- Side effects: hyperkalemia and acidosis
8
Q
Spironolactone and Eplereone
A
- Potassium sparing agents
- Inhibit aldosterone by combining with and block the intracellular aldosterone receptor
- Thus, decrease expression of genes controlling synthesis of sodium ion channels and Na+/K+-ATPase
9
Q
Amiloride and Triamterene
A
- Potassium sparing agents
- Na+ channel blockers
10
Q
Osmotic diuretics
A
- Mannitol (IV), Glycerin, Isosobide, Urea
- Mannitol inhibits water reabsorption though out the tubule, by osmotic effects. It is filtrated in the glomeruli, but are poorly reabsorbed.
- Mainly act at the proximal convoluted tubule
- Used to decrease IOP in glaucoma, decrease intracerebral pressure, and used in oliguric states to maintain urine flow
- Side effects: acute hypovolemia, hyponatremia, pulmonary edema
11
Q
Antidiuretic hormone (ADH) agonists
A
- ADH and Desmopressin
- Must be given parenterally
- Activate V2 receptors on the collecting tubule, which stimulates adenylyl cyclase via Gs. The increased cAMP causes the insertion of additional aquaporin water channels
- Cause an reduction in urine volume and increase its concentration
- Used in pituitary diabetes indsipidus
- Side effects: hyponatremia, hypertension
12
Q
Antidiuretic hormone (ADH) antagonists
A
- Demeclocycline and Lithium
- Inhibit the action of ADH at some point distal to the generation of cAMP and presumably interfere with the insertion of water channels
- Act at the same V2 receptors as ADH
- Used to treat syndrome of inappropriate ADH secretion (SIADH) (not Lithium)
- Side effects: bone and teeth abnormalities (Demeclocycline), nephrogenic diabetes insipidus (Lithium)
13
Q
Urinary antiseptics
A
- Nitrofurantoin, Nalidixic acid, Methenamine
14
Q
Nitrofurantoin
A
- Urinary antiseptic
- Active against many urinary tract pathogens (not Proteus or Pseudomonas)
- Single daily doses of the drug can prevent recurrent urinary tract infections
- Side effects: GI irritations, skin rashes, photo toxicity, neuropathies, hemolysis
15
Q
Nalidixic acid
A
- Urinary antiseptic
- Act against many gram-negative organisms (not Proteus or Pseudomonas)
- Act by acidification or inhibition of DNA gyrase in bacteria
- Side effects: GI irritation, glycosuria, skin rashes, photo toxicity, visual disturbances, CNS stimulation
