Renal Drugs

Question 1

Thiazide Diuretics

Example(s) of drugs:

Answer 1

Bendroflumethazide
Indapamide
Chlortalidone

Question 2

Thiazide Diuretics

Mechanism of action:

Answer 2

Inhibit Na+/Cl- transporter at the distal convoluted tubule and collecting duct
Increases Na+, Cl- and water excretion

Question 3

Thiazide Diuretics

Indication(s):

Answer 3

Hypertension
Oedema of cardiac / renal / hepatic / iatrogenic origin

Question 4

Thiazide Diuretics

Side effects:

Answer 4

• Hypokalaemia
• Hypomagnesaemia
• Hyponatraemia
• Hypercalcaemia
• Hyperuricaemia
• Reduced glucose tolerance
• Hypersensitivity reactions – rashes, pneumonitis (less common)

Question 5

Thiazide Diuretics

Important pharmacokinetics / pharmacodynamics:

Answer 5

• Produces diuresis quickly within 1-2 hours
• NSAIDs reduces efficacy of thiazide diuretics
• Note that urinary symptoms are less common with the lower doses used for the treatment of hypertension.

Question 6

Thiazide Diuretics

Patient information:

Answer 6

• Urinary frequency usually not affected
• Report if sudden rash
• Make aware of risk of electrolyte imbalance

Question 7

Loop Diuretics

Example(s) of drugs:

Answer 7

• Furosemide
• Bumetanide
• Torasemide

Question 8

Loop Diuretics

Mechanism of action:

Answer 8

• Na+/Cl-/K+ symporter antagonists
• Act on the thick ascending loop of Henle
• Increase secretion of Na+, K+, Cl- and water

Question 9

Loop Diuretics

Indication(s):

Answer 9

• Hypertension
• Hyperkalaemia
• Heart failure
• Cirrhosis of liver (fluid retention)
• Nephrotic syndrome

Question 10

Loop Diuretics

Side effects:

Answer 10

• Hypokalaemia, hypovolaemia, hyperuricaemia (increased urate reabsorption)
• Metabolic acidosis
• Abdominal pain
• Ototoxicity

Question 11

Loop Diuretics

Side effects:

Answer 11

• Hypokalaemia, hypovolaemia, hyperuricaemia (increased urate reabsorption)
• Metabolic acidosis
• Abdominal pain
• Ototoxicity

Question 12

Loop Diuretics

Important pharmacokinetics / pharmacodynamics:

Answer 12

• 60% absorbed in patients with normal renal function
• Renal and hepatic excretion – increased half life for patients with renal or hepatic disease

Question 13

Loop Diuretics

Patient information:

Answer 13

• Avoid excess alcohol
• Urinary frequency increases

Question 14

Insulin

Example(s) of drugs:

Answer 14

Novorapid
Glargine
Humalog Mix

Question 15

Insulin

Mechanism of action:

Answer 15

• Insulin increases cellular uptake of glucose
• It stimulates glycogenesis, encourages DNA synthesis and promotes release of growth hormone
• Several types of exogenous insulin:
• Short acting: Novorapid
• Long acting: Glargine
• Fast-acting and Intermediate-acting mix: Humalog Mix

Question 16

Insulin

Indication(s):

Answer 16

• Type 1 Diabetes Mellitus
• Type 2 Diabetes Mellitus
• Hyperkalaemia (in conjunction with dextrose)

Question 17

Insulin

Side effects:

Answer 17

• Hypoglycaemia
• Sweats / shakes / tachycardia / headache / weakness / fatigue (typically symptoms of hypoglycaemia)
• Oedema
• Injection site reactions

Question 18

Insulin

Important pharmacokinetics / pharmacodynamics:

Answer 18

• Patients are given varying types of insulin combinations based on their activities and preferences
• Given subcutaneously and short acting insulin (actrapid) can be given intravenously.

Question 19

Insulin

Patient information:

Answer 19

• Only in the form of injection
• Compliance important
• Never skip meals while on insulin

Question 20

Insulin

Other information:

Answer 20

Four types of insulin based on onset of action, peak time and the duration of action.

A. Rapid acting insulin (Novorapid):

1. Reaches circulation within 15 minutes after injection
2. Peaks 30 to 90 minutes later
3. Lasts for up to 5 hours

B. Short acting

1. Reaches circulation 30 mins after injection
2. Peaks 2 – 4 hours later
3. Lasts for up to 4 to 8 hours

C. Intermediate acting

1. Reaches circulation in 2 – 6 hours
2. Peaks 4 – 14 hours later
3. Lasts for up to 20 hours

D. Long acting (Glargine)

1. Reaches circulation in 6 to 14 hours
2. Minimal peak
3. Lasts for up to 24 hours

Question 21

Osmotic diuretic:

Example of drug

Answer 21

Mannitol

Question 22

Osmotic diuretic site of action

Answer 22

Proximal convoluted tubules and descending LOH

Question 23

Osmotic diuretic

Indication

Answer 23

• raised intracranial pressure
• raised intraocular pressure (glaucoma)

Question 24

Osmotic diuretic mechanism of action

Answer 24

• freely filtered at the the glomerulus
• but only partiallify reasbsorped
• Passive water reabsorption is reduced by the presence of this non-reabsorbable solute within the tubule lumen
• net effect is increased water loss, with a relatively smaller loss of sodium

Question 25

Osmotic diuretic: Contra-indications

Answer 25

Congestive heart failure, pulmonary oedema

Question 26

Osmotic diuretic: Side effects

Answer 26

Chills, fever

Question 27

Potassium sparing diuretic example

Answer 27

Spironolactone, amiloride

Question 28

Potassium diuretic site of action

Answer 28

Late distal tubule and collecting ducts

Question 29

Two classes of potassium sparing diuretics

Answer 29

* **Sodium-channel blockers -** amiloride * block sodium reabsoprtion by the principals cells and this reducing the potential difference across the cell and reducing K+ secretion. Secretion of H+ from the intercalated cells is also decreased * **Aldosterone antagonists -** eg spironolactone * competitive antagonist at aldosterone receptors and thus reduces Na+ reabsorption and therefore K+ and H+ secretion. The degree of diuresis depends on aldosterone levels

Question 30

Potassium Sparing diuretic Indications

Answer 30

* in conjuncton with other diuretics (thiazides, loops) in managing heart failure or hypertension, to aintain normal serum potassium levels * aldosterone antagonists are used in the treatment of hyperaldosteronis, which can be primary (Conns) or secondary (as a result of CHF, liver disease or nephrotic syndrome)

Question 31

Potassium sparing diuretics Contraindication

Answer 31

Dont give with ACE inhibitors as risk of hyperkalaemia

Question 32

Potassium sparing diuretics Adverse effects

Answer 32

* hyperkalaemia * hyponatremia * aldosterone agonists - gynaecomastia