Renal Pharmacology (Diuretics) Flashcards
How do diuretics work?
- Increase daily urine output
- Act by increasing the excretion of H2O, often through decreased re-absorption of ions (Na+, Cl-, and/or HCO3) by the renal tubular system
- Increased ion excretion results in increased H2O excretion due to osmotic effects
What organ has a tremendous capacity for producing an ultrafiltrate from plasma?
Kidneys
The _____ is the site of ultrafiltration.
Glomerulus
The _____ contains highly specialized cells that contain ion transport systems and have water permeable properties
Tubular system
What controls hormones?
Antidiuretic hormone (ADH) - Vasopressin
Aldosterone
What are the uses of a diuretic?
- Congestive HF
- Kidney disease
- Hepatic cirrhosis
- Idiopathic edema
- Nephrolithiasis (kidney stones)
- Hypercalcemia
- Nephrogenic diabetes insipidus
- HTN
What are the 5 sites on a Nephron?
- Proximal convoluted tubule
- Descending loop of Henle
- Ascending loop of Helne
- Distal convoluted tubule
- Collecting duct
Where do osmotic (Acetazolamide, Mannitol and Urea) diuretics act?
Proximal convoluted tubule
(weak diuretic properties) - Carbonic anhydrase inhibitor which inhibits reabsorption of HCO3-
Where do loop (Furosemide) diuretics act?
Ascending loop (most efficient diuretics)
Where to thiazide (chlorothiazide) diuretics act?
Distal convoluted tubule (most commonly used diuretic
Where to potassium sparing (Spironolactone and Triaterene) diuretics act?
Collecting tubule (prevent loss of K that occur in thiazide or loop diuretics.
Explain the MOA in osmotic diuretics
Freely filtered through Glomerulus. Increases osmolarity of tubular fluid. This hinders water re-absoprtion in proximal tube (major site), descending loop, and collecting tubules
Explain the MOA in loop diuretics
Inhibition of the coupled Na+/Cl-/K+ transport system in thick ascending loop. Net effect: Na+, Cl-, Ca++, Mg++
Explain the MOA in thiazide diuretics
Inhibition of Na+/Cl- transport system. Net effect: increased secretion of Na+ and Cl-; decreased re-absorption of Ca++
Explain the MOA in potassium sparing diuretics
Loop diuretics and thiazide diuretics increase Na+ excretion upstream of the collecting tubule, causing an increase delivery of Na+ to this part of the nephron.
The impact of this increase on Na+ is to cause an increase in K+ release from this site, an effect that can lead to hypocalemia (K deficiency)
Potassium-sparing diuretics in comb with loop or thiazide diuretics can minimize this K loss.
