Diuretics Drugs in treatment Hypertension

Diuretics Drugs in treatment Hypertension

Thiazide diuretics: As HydroChloroThiaZide (HCTZ) PO 12.5 or25mg onced aily)

-Antihypertensive effects can be achieved in many patients with 12.5 mg daily of Chlorthalidone or Hydrochlorothiazide

-When used as monotherapy → the maximal daily dose → should not exceed 25 mg of Hydrochlorothiazide or Chlorthalidone.

Thiazide diureticsinitially  BP by inhibit Na+/ Cl¯ & H2O re-absorption blood volume → ECF volume shrink ,so→ COP declines

After 6–8 weeks → COP returns toward normal while PVR declines

– Thiazide diuretics act primarily on the kidney but secondarily on Blood vessels

Therefore the initial antihypertensive  effect seem to be mediated by ↓intravascular volume ↓COP ↓BP → ↓ preload

-With chronic use the plasma volume returns to nearly pre-treatment level after a few weeks due to development of tolerance after prolonged use

Mechanism of action of Thiazide diuretics Mechanism of action of Thiazide diuretics

see this image also>>

MoA of Thiazide diuretics:

Mechanism of action of Thiazide diuretics



Therefore the initial antihypertensive  effect seem to be mediated by ↓intravascular volume ↓COP ↓BP → ↓ preload

then cause decrease of total vascular resistance.

-With chronic use the plasma volume returns to nearly pre-treatment level after a few weeks due to development of tolerance after prolonged use

see this image>>

chronic use → the plasma volume returns to nearly pre-treatment level

  • Advantages of Thiazides:

The pharmacokinetic & pharmacodynamic characteristics of the Thiazides make them especially useful in the treatment of chronic HTN.

  1. Thiazide diuretics have longer duration of action than loop diuretic
  2. They are well tolerated even in elderly patients
  3. They the incidence of fracture in elderly patients
  • Therapeutic uses of Thiazides:

HTN: Hydrochlorothiazide  the 1st line therapy (DOC) that can provide adequate treatment for primary mild to moderate HTN with otherwise normal heart & kidney function

Thiazide diuretics preferred in:

  1. -Particularly effective in patients with volume-based HTN & African-American patients (black)
  2.  Elderly patients & ISH in elderly

Therapeutic uses of Thiazides

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