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Clinical pharmacy 2024/2025 Level 3 Pharm D Pharmacology 1 (PO 502)

 Thiazide ex: Hydrochlorothiazide and Chlorothiazide

➢ All oral diuretics are effective in the treatment of hypertension, but thiazide is the
most widespread use.
➢ Chlorothiazide -------- the prototype of the thiazide group

➢ Hydrochlorothiazide is now used more common; it is more potent than
Chlorothiazide (lower dose)

Site of action ➢ act on cortical region of ascending loop of Henle.

Caution ➢ Must be excreted to be active (must reach kidney in active form),
➢ C.I in kidney problem.

➢ ↓ BP ➔ by ↑ Na, Water excretion ➔↓ extracellular volume ➔
↓ C.O.P, renal Blood flow
➢ ↓ B.P in both Supine and standing position
Action ➢ With long term ➔ Normalization of BP plasma volume reach

normal, but ↓ P.R
+
➢ counteract the Na & water retention observed with use of other
agents used for hypertension as hydralazine (direct VD)

1- useful ttt hypertension in black & elderly patients > 65 (genetic
variation) over β-Blocker
 With the exception of Metolazone (thiazide like) are not effective in
Uses patients with inappropriate kidney function especially Clearance
< 50ml/min (thiazides C.I), but Loop diuretics are more favorable.
2- in combination with other antihypertensive agents including β-
+
blockers, ACEIs, ARBs and K sparing diuretics

C/I ➢ Patients having renal stones & patients with poor renal function
(poor glomerular filtration rate)

1) Hypokalemia  hypokalemic metabolic alkalosis.

2) Hyperglycemia  due to diuretic-induced potassium deficiency
 insulin release (C/I: diabetes).
S/E
3) Hyperuricemia  due to inhibition of uric acid secretion from the
proximal tubule  development of gout (C/I)

4) Hyperlipidemia

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