CVS - Diuretics - Drugs affecting fluid & electrolytes Flashcards Preview

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Flashcards in CVS - Diuretics - Drugs affecting fluid & electrolytes Deck (16):
1

Classes of diuretics & examples

1. Caffeine
2. Carbonic Anhydrase Inhibitors (Acetazolamide)
3. Loop Diuretics (Furosemide, Ethacrynic Acid)
4. Thiazide Diuretics (Hydrochlorothiazide)
5. Potassium Sparing Diuretics (Spironolactone, Triamterene)
6. ADH/Vasopressin Antagonists (Lithium, Vaptans)

2

Uses of diuretics (3+4)

Edematous States
1. Heart Failure
2. Renal Disease & Renal Failure (due to Na retention by kidney)
3. Hepatic Cirrhosis (often resistant to loops, use spirono)

Non-edematous States
1. Hypertension
2. Nephrolithiasis
3. Hypercalcemia
4. Diabetes Insipidus

3

Mechanism of action of caffeine

Weak antagonist of adenosine receptors - A1 receptor antagonist - blocks PT reabsorption of Na+

4

Mechanism of action of CAI

Blocks NaHCO3 reabsorption

5

Uses of CAI (4)

1. Glaucoma - reduces aq humour formation & intraocular pressure
2. Acute Mountain Sickness - reduces CSF production & pH - increases ventilation - decreases pulmonary/cerebral edema
3. Metabolic Alkalosis
4. Urinary Alkalinization - enhances excretion of weak acids

6

Mechanism of action of loop diuretics

1. Inhibits NKCC2 co transporter - selectively inhibits NaCl reabsorption - decreased lumen positive potential - increased cation secretion
2. Increased expression of COX-2 - catalyses PGE2 production from arachidonic acid - PGE2 inhibits NaCl transport in TAL

7

Uses of loop diuretics (6)

1. Acute Pulmonary Edema
2. Other edematous conditions
3. Acute Hypercalcemia
4. Mild Hyperkalemia
5. Acute Renal Failure - enhances urine flow & K+ excretion, flushes intratubular casts
6. Anion Overdose

8

Toxicity of loop diuretics (5)

1. Hypomagnesemia - prolonged use, reversible with oral Mg
2. Hypokalemic Metabolic Alkalosis - reversible by K+ replacement & rehydration
3. Ototoxicity - esp with poor renal function
4. Hyperuricemia, precipitate gout attacks - due to hypovolemic associated enhanced reabsorption of uric acid
5. Allergic Reactions

9

Mechanism of action of thiazide diuretics

1. Inhibits NaCl reabsorption by blocking Na/Cl cotransporter
2. Enhances Ca reabsorption (A) passively in PCT due to hypovolemia (B) Na/Ca exchanger on basolat membrane in DCT by decreasing intracellular Na

10

Uses of thiazide diuretics (4)

1. Hypertension
2. Heart Failure
3. Nephrolithiasis - due to idiopathic hypercalciuria
4. Nephrogenic Diabetes Insipidus

11

Toxicity of thiazide diuretics (6)

1. Hypokalemic Metabolic Alkalosis
2. Hyperuricemia (Gout)
3. Impaired Carbohydrate Tolerance - impaired insulin release & impaired tissue glucose utilization
4. Hyperlipidemia
5. Hyponatremia - reduce dose and limit H2O intake
6. Allergic Reactions

12

Mechanism of action of K+ sparing diuretics

Antagonizes effects of aldosterone in CCT - prevents K+ secretion
1. Direct antagonism of mineralocorticoid receptors (spironolactone, eplerenone)
2. Inhibits Na+ influx through ENaC (amiloride, triamterene)

13

Uses of K+ sparing diuretics (2)

1. Primary Hyperaldosteronism
2. Secondary Hyperaldosteronism

14

Toxicity of K+ sparing diuretics (5)

1. Hyperkalemia
2. Hyperchloremic Metabolic Acidosis
3. Gynecomastia
4. Acute Renal Failure
5. Kidney Stones

15

Mechanism of action of ADH antagonists

Lithium: anti-ADH
Vaptans: non-peptide V1a & V2 receptors antagonist

16

Toxicity of ADH antagonists (1)

1. Nephrogenic Diabetes Insipidus