Pharmacology

Question 1

What is natriuresis

Answer 1

Process of excretion of sodium in the urine via action of the kidneys

Question 2

What factors promotes natriuresis

Answer 2

Ventricular natriuretic peptide
ANP
Calcitonin

Question 3

Ventricular natriuretic peptide is secreted by

Answer 3

Ventricular myocardium of the heart due to stretches of the wall

Question 4

What factors inhibit natriuresis

Answer 4

Aldosterone

Question 5

Inhibiting natriuresis =

Answer 5

Conserving sodium -> increase in blood volume due to osmosis

Question 6

Promoting natriuresis =

Answer 6

Decrease in sodium in blood -> decrease in blood volume due to osmosis (water follows sodium) -> increase in urine production

Question 7

Why is K+ balance important

Answer 7

Because K+ can effect the functions of excitable cells such as muscle cells (Na K pump maintains the potential gradient of the cell)

Question 8

How does the kidneys maintain K+ balance

Question 9

mechanism of diuretics

Answer 9

Drugs that increases the volume of urine by promoting excretion of Na+, Cl-, HCO3 and water

Net result = increase in urine flow and altered pH and ionic composition (because it takes other ions with it as well)

Question 10

Diuretics causes increase in urine volume but this also means it can take other ions with it. What is a side effect of diuretic

Answer 10

Hypokalaemia - due to increased excretion of urine = increased excretion of K+

Question 11

Symptoms of hypokalaemia

Answer 11

Muscle cramps & pain
Palpitations
Constipation
Arrhythmias
Rhabdomyolysis

Question 12

What arrhythmia is seen in hypokalaemia

Answer 12

Flat T waves
ST depression
Prominent U waves
Prolonged PR

Question 13

Types of diuretics

Answer 13

Osmotic diuretics
Carbonic anhydrase inhibitors
Loop diuretics
Thiazide
K+ sparing diuretics

Question 14

Site of action of osmotic diuretics

Answer 14

Proximal tubule
Loop of Henle
Collecting duct

Question 15

What is the mechanism of action of osmotic diuretics

Answer 15

Inhibition of water and Na+ reabsorption

Question 16

Examples of osmotic diuretics

Answer 16

Mannitol
Isosorbide
Glycerine

Question 17

Which osmotic diuretic is only given through IV injections and why

Answer 17

Mannitol

because body cells lack transport mechanisms for it hence it won’t be able to penetrate cell membranes

Question 18

Which osmotic diuretic is the most preferred

Answer 18

Mannitol

Question 19

Indications of osmotic diuretic

Answer 19

Prevent acute renal failure - Mannitol
Reduce intraocular pressure
Reduce intracranial pressure - Mannitol and urea
Reduce cerebral edema - Mannitol and urea

Question 20

Side effects of osmotic diuretic

Answer 20

Cardiovascular toxicity
- injection causes osmosis of non-vascular fluids into the vessel
- increases blood volume
- increases workload of the heart

Question 21

Contraindication of osmotic diuretic

Answer 21

Patients with congestive heart failure

Question 22

Examples of carbonic anhydrase inhibitors

Answer 22

Acetazolamide
Methazolamide

Question 23

Site of action of carbonic anhydrase inhibitors

Answer 23

Proximal tubule

Question 24

What is the role of carbonic anhydrase in proximal tubules

Answer 24

1. Carbonic anhydrase forms H2CO3 in cell from CO2 + H2O
2. H2CO3 then dissociates into HCO3- and H+
3. HCO3- is reabsorbed = conserved
4. With each H+ is excreted, a Na+ is reabsorbed = retention of water

Question 25

How does carbonic anhydrase inhibitors work

Answer 25

Inhibits the formation of H2CO3 hence it will not dissociate into H+ and HCO3
H+ will therefore not be excreted with a Na+ reabsorbed
= no reabsorption of Na+

Question 26

Indications of carbonic anhydrase inhibitors

Answer 26

Raised intra-ocular pressure in open angle glaucoma
Ocular hypertension

Question 27

Side effects of carbonic anhydrase inhibitors

Answer 27

Metabolic acidosis
Renal stones
Renal potassium wasting