The thiazides act in the distal tubule to
decrease sodium reabsorption (inhibits Na/Cl
transporter). As a result of decreased sodium and
chloride reabsorption, a hyperosmolar diuresis
Delivery of more sodium to the distal
tubule results in potassium loss by an exchange
Thiazides also promote calcium
reabsorption, in contrast to loop diuretics.
The initial decrease in blood volume
followed by a longer-termed reduction in vascular
resistance appears to account for the hypotensive
effects of the thiazides.
Potassium depletion is a potentially
serious side-effect that may require potassium
supplementation and/or concurrent use of
Hyperuricemia may occur precipitating
gout. The increase in systemic uric acid is due
to a decrease in the effectiveness of the organic
acid secretory system
Diabetic patient may have difficulty in
maintaining proper blood sugar levels.