Diuretics

Question 1

Classification of diuretics

Answer 1

High ceiling or loop diuretics
Medium efficacy
Adjunctive / weak diuretics

Question 2

Examples of high ceiling diuretics

Answer 2

Furosemide
Bumetanide
Torasemide

Question 3

Sub classification of medium efficacy diuretics and examples

Answer 3

Benzothiadiazines: hydrochlorothiazide, hydroflumethazide

Thiazide like: chlorthalidone, metolazone, xipamide, indapamide, clopamide

Question 4

Sub classification of weak diuretics and examples

Answer 4

CAse inhibitors: acetazolamide

K+ sparing:
Aldosterone antagonist- spironolactone
Renal epithelial Na+ Chanel inhibitors- amiloride, triamterene

Osmotic diuretics: mannitol, glycerol, isosorbide

Question 5

Duration of action of furosemide

Answer 5

3-6 hours (short)

Question 6

Site of action of furosemide

Answer 6

Thick Ascending limb of LOH inhibiting Na+-k+-2cl- cotransport

Question 7

Action of furosemide in corticomedullary osmotic gradient and free water clearance

Answer 7

Corticomedullary osmotic gradient is abolished and positive and negative free water clearance is blocked

Question 8

Action of furosemide in gfr and rbf

Answer 8

Rbf increases, gfr same

Question 9

Why is furosemide used in LVF and pulmonary edema

Answer 9

Intravenous furosemide causes prompt increase in systemic venous capacitance which decreases Left ventricular pressure.

Question 10

What happens to ca and mg in furosemide action

Answer 10

Ca and mg both decreases

Question 11

Which drug is 40 times more potent than furosemide, highly effective in pulmonary edema and induced very rapid diuresis. It is preferred for oral absorption in CHF, as it is not affected by edema of the bowels

Answer 11

Bumetanide

Question 12

Torasemide is used in

Answer 12

Edema and hypertension

Question 13

Uses of high ceiling diuretics

Answer 13

Edema
Acute pulmonary edema (LVF, After MI)
Cerebral edema
Hypertension
Blood transfusion
Hypercalcemia of malignancy

Question 14

Site of action of thiazide diuretics

Answer 14

Cortical diluting segment or early DT
Inhibits Na+-CL- symport

Question 15

Action of thiazides on free water clearance and corticomedullary osmotic gradient

Answer 15

Corticomedullary osmotic gradient not affected
Positive free water clearance reduced
Negative free water clearance not affected

Question 16

Action of thiazides on gfr

Answer 16

Reduces gfr

Question 17

Action of thiazides on ca and mg

Answer 17

Ca excretion decreases
Mg excretion increases

Question 18

Duration of action of thiazides

Answer 18

6-48 hours varies

Question 19

Examples of thiazides

Answer 19

Chlorthalidone
Metolazone
Xipamide
Indapamide

Question 20

Uses of thiazides

Answer 20

Edema
Hypertension
Diabetes insipidus
Hypercalciuria

Question 21

Complications of high ceiling and thiazides

Answer 21

Hypokalemia
Acute saline depletion
Dilutional hyponatremia
GIT and CNS disturbances
Allergic reaction
Hearing loss
Dyslipedemia and hyperglycemia
Hyperuricemia
Magnesium depletion
Hypocalcemia (loop diuretics only)
Aggravated renal insufficiency (thiazides only)
Toxemia of pregnancy
Mental disturbances

Question 22

Interactions of thiazides and high ceiling diuretics

Answer 22

Potentiate all hypertensives
Hypokalemia enhances digoxin toxicity, reduces sulphonyl urea action, increases risk of polymorphic ventricular tachycardia due to drugs which prolong Q-t interval
High ceiling diuretics and aminoglycoside antibiotic and both ototoxic and nephrotixic with concurrent use
Indomethacin and NSAID inhibits PG synthesis and diminish action of loop diuretics
Probencid inhibits diuretic action

Question 23

CA present in

Answer 23

Renal tubular cell (PCT)
Gastric mucosa
Exocrine pancreas
Ciliary body of eye
Brain
RBC

Question 24

Examples of CAse inhibitor

Answer 24

Acetazolamide
Methazolamide
Dichlorphenamide

Question 25

Uses of CAse inhibitors

Answer 25

Glaucoma Epilepsy Mountain sickness To alkalinise urine Periodic paralysis

Question 26

Extra renal actions of acetazolamide

Answer 26

Lowers Intraocular tension Decrease gastric HCL secretion Raised level of Co2 in brain which decreases PH Alteration of Co2 transport in lungs and tissues

Question 27

Why is acetazolamide not used as a diuretic

Answer 27

Because of its self limiting action, production of acidosis and Hypokalemia

Question 28

Two classes of K+ sparing diuretics with examples

Answer 28

Aldosterone antagonist - spironolactone, eplerenone Renal epithelial Na+ channel inhibitors- amiloride, triamterene

Question 29

Spironolactone MOA

Answer 29

Inhibits formation of AIP by combining with Mineralocorticoid receptor (MR)

Question 30

Spironolactone actions

Answer 30

Increases Na+ secretion Decreases K+ excretion Mild saluretic Increases Ca2+ excretion

Question 31

Most important active metabolite of spironolactone

Answer 31

Canrenone

Question 32

Uses of spironolactone

Answer 32

Edema To counter act K+ loss due to other diuretics Hypertension CHF Primary hyperaldosteronism

Question 33

Interactions of spironoloactone

Answer 33

Spironolactone + k+ supplements give hyperkalemia Aspirin blocks it by inhibiting synthesis of canrenone Hyperkalemia in presence of ACe inhibitors Increases plasma digoxin concentration

Question 34

Most serious problem with spironolactone

Answer 34

Hyperkalemia And testosterone action

Question 35

Alternative to spironolactone which has no androgen and progesterone action

Answer 35

Eplerenone

Question 36

Renal epithelial Na+ channel inhibitors example

Answer 36

Triamterene and amiloride

Question 37

Most important adverse effect of traimterene and amiloride

Answer 37

Hyperkalemia

Question 38

Uses of mannitol

Answer 38

1. In increased intracranial or intra ocular tension 2. To maintain gfr 3. To counteract low osmlolality of plasma ecf due to rapid haemodialysis