Thiazide and Thiazide-like Diuretics

Question 1

What are the indications for Thiazide & Thiazide-like diuretics?

Answer 1

HTN
* As an alternative 1st line Tx for HTN instead of a CCB due to edema
* As an add on Tx if BP not controlled by CCB + ACE inhibitor or ARB

Question 2

Name some examples of Thiazide-like diuretics?

Answer 2

1. Indapamide
2. Chlortalidone

Question 3

Name examples of Thiazide diuretics?

Answer 3

1. Bendroflumethiazide
2. Hydrochlorothiazide (HCTZ)

Question 4

What is the MOA action?

Answer 4

Thiazides inhibit the Na/CL co-transporter in the distal convoluted tubule of the nephron, thus preventing the reabsorption of Na and its osmotically associated water. This causes a fall in the extracellular fluid volume

Question 5

What are the side effects?

Answer 5

1. Hyponatremia
2. Hypokalemia
3. Impotence in men
4. Increase plasma concentrations of:
   * Glucose (may unmask type 2 DM)
   * LDL - cholesterol & Triglycerides

Question 6

How do you monitor a person on Thiazide & Thiazide-like diuretics?

Answer 6

Get a baseline U&E before starting, repeat 2-4 weeks into treatment and after increasing dose.

Question 7

Thiazide & Thiazide-like diuretics are contraindicated in patients with?

Answer 7

1. Hyponatremia
2. Hypokalemia
3. Gout (they reduce uric acid excretion)

Question 8

Which drugs interact with Thiazide & Thiazide-like diuretics negatively?

Answer 8

• NSAIDS (NOT aspirin) - reduce its effectiveness
• Other serum potassium lowering drugs (e.g., loop diuretics)

Question 9

What benefit does a of ACE inhibitor / ARBs + Thiazide diuretic combination have on serum potassium?

Answer 9

A side effect of Thiazide diuretics is hypokalemia, while a side effect for ACE inhibitors / ARBs is hyperkalemia. Thus using both would not only improve BP but also maintain a neutral potassium balance.