Session 9

Question 1

Describe the role of carbonic anhydrase inhibitors.

Answer 1

Cause sodium carbonate diuresis, excretion of sodium, potassium and phosphate. Acts at the PCT. Affects reabsorption of sodium.

Question 2

Describe the role of osmotic diuretics.

Answer 2

Increase osmotic gradient systemically. Can causes excessive water loss and cause hypernatraemia.

Question 3

Describe the role of loop diuretics.

Answer 3

Affect the descending, thick limb of the loop of henle, used in oedematous states. Inhibits NaCl reabsorption, hence excretion of calcium and magnesium. Can cause hypokalaemia.

Question 4

Describe the role of thiazides.

Answer 4

Inhibit NaCl reabsorption, promoting calcium reabsorption.

Question 5

Describe the role of potassium sparing diuretics.

Answer 5

Act on the ENac channel in the late DCT and CD. Have no effect on potassium.

Question 6

Describe the role of aldosterone antagonists.

Answer 6

Inhibit action of aldosterone on mineralocorticoid receptors, hence affecting NaKATPase and ENaC protein synthesis. Inhibits sodium retention.

Question 7

Describe the role of ADH antagonists.

Answer 7

Reduces concentrating ability of urine in collecting ducts.

Question 8

Give two ADRs of diuretics.

Answer 8

Anaphylaxis, hypovolaemia, electrolyte disturbance, metabolic abnormalities, hyperkalaemia, erectile dysfunction etc.

Question 9

Give two major indications of diuretics.

Answer 9

Heart failure, hypertension, decompensated liver disease.

Question 10

Give two examples of drugs causing renal complications.

Answer 10

ACE-inhibitors, aminoglycosides, penicillins, metformin and NDAIDs.

Question 11

What can renovascular disease cause?

Answer 11

Renal artery stenosis, reducing renal function.

Question 12

How do you manage hyperkalaemia?

Answer 12

Identify and remove the cause.
Absent P waves, prolonged QRS and tall T-waves.
Calcium gluconate, insulin, sodium bicarbonate and salbutamol.

Question 13

How is an increase in blood pressure managed physiologically?

Answer 13

Downregulation of RAAS and reduced vasoconstriction. Causing decreased peripheral resistance. PNS is also upregulated, causing decreased cardiac output and a reduced BP.

Question 14

Give three complications of high blood pressure.

Answer 14

• Increased arterial thickening
• Smooth muscle cell hypertrophy
• Loss of arterial compliance
• Target organ damage

Question 15

Three pieces of lifestyle advice for high blood pressure.

Answer 15

Maintain normal weight, reduce salt intake, limit alcohol, eat lots of fruit and veg, reduce fat intake, stop smoking.

Question 16

How do ACE-inhibitors work to lower blood pressure?

Answer 16

E.g. Ramipril. Inhibit ACE activity, preventing generation of angiotensin 2. Causes arteriolar vasodilation and prevents bradykinin breakdown. Reduced sodium and water reabsorption.

Question 17

How do angiotensin receptor blockers work to lower blood pressure?

Answer 17

E.g. Losartan. Bind to AT1 receptors and inhibit vasoconstriction and aldosterone stimulation.

Question 18

How do calcium channel blockers work to lower blood pressure?

Answer 18

Bind to subunit of L-type calcium channels, reducing calcium entry. They vasodilate peripheral, coronary and pulmonary arteries.

Question 19

What are the three groups of calcium channel blockers?

Answer 19

1) Dihydropyridines, e.g. Amlodipine
2) Benzothiazepines, e.g. Diltiazem
3) Phenylalkylamines, e.g. Verapamil.

Question 20

How does verapamil work?

Answer 20

Depresses SA node and slows AV conduction. Impedes calcium transport across the myocardial and vascular smooth muscle membrane. Peripheral vasodilatation and reduced preload and myocardial contractility.

Question 21

How do thiazide diuretics work to lower blood pressure?

Answer 21

E.g. bendroflumethiazide. Reduces distal tubular sodium reabsorption by acting on the NaCl symporter in the DCT.

Question 22

Give three secondary causes of hypertension.

Answer 22

Cushing’s syndrome, thyroid disease, hyperparathyroidism, renovascular hypertension, diabetic renal disease, coartation of the aorta, OCP, pregnancy.

Question 23

How would you treat an hypertensive emergency?

Answer 23

IV sodium nitroprusside. This acts as nitric oxide, causing vasodilation and rapidly reduces BP.

Question 24

What is heart failure?

Answer 24

When the cardiac output is insufficiently adequate to perfuse the tissues, despite normal filling of the heart.

Question 25

What are the main symptoms of heart failure?

Answer 25

Fatigue, breathlessness and exercise intolerance.

Question 26

How would you treat heart failure?

Answer 26

• Start with an ACE-inhibitor to reduce load on the heart
• Add a diuretic to reduce circulating volume
• Add digoxin to increase force of contraction
• Add a beta-blocker
• Add spironolactone.

Question 27

Give two side-effects of ACE-inhibitors and beta-blockers.

Answer 27

ACE-inhibitors: dry cough, light headedness, fatigue, upset stomach, oedema.
Beta-blockers: depression, fatigue, light headedness and memory loss.

Question 28

Give two side-effects of diuretics and digoxin.

Answer 28

Diuretics: hyponatraemia, dizziness, headaches, dehydration.
Digoxin: dizziness, change in mood, anxiety, nausea, vomiting and diarrhoea.