thiazides in hypertension

Last edited 09/2019 and last reviewed 06/2022

Thiazide diuretics are effective antihypertensive agents in the treatment of hypertension.

They have been shown to reduce the cardiovascular complications of hypertension - thiazide diuretics have been shown to reverse target organ damage (left ventricular hypertrophy) to the same extent as the newer antihypertensive agents (1,2).

Indications for the use of thiazides in the treatment of hypertension include (3):

• compelling indication - elderly patients including isolated systolic hypertension
  • in older patients with isolated systolic hypertension, diuretic based, stepped care antihypertensive therapy has been shown to reduce long term cardiovascular mortality (4). Patients who had diabetes at baseline or who developed diabetes during follow up and received stepped care had lower mortality than did those who received placebo

Contraindications for the use of thiazides in the treatment of hypertension include (3):

• possible contraindication - dyslipidaemia
• compelling contraindication - gout

Unwanted effects include:

• glucose intolerance
• hypokalaemia
• a 1% increase in cholesterol
• gout
• impotence

Unwanted effects are less common if low-doses are administered, such as bendroflumethiazide (bendrofluazide *) 2.5 mg / day.

* Bendroflumethiazide became the British Approved Name for bendrofluazide in 2004

Notes:

• NICE have stated that when considering a diuretic in treatment of hypertension then the clinician should offer a thiazide-like diuretic e.g: chlortalidone (12.5-25.0 mg once daily) or indapamide (1.5 mg modified-release once daily or 2.5 mg once daily) in preference to a conventional thiazide diuretic such as bendroflumethiazide or hydrochlorothiazide (5)

Reference:

1. Gosse P et al (2000). Regression of left ventricular hypertrophy in hypertensive patients treated with indapamide SR 1.5mg versus enalapril 20mg: the LIVE study. J Hypertens; 18: 1465-75.
2. Grimm RH et al (1996). Long-term effects on plasma lipids of diet and drugs to treat hypertension. Treatment of Mild Hypertension Study (TOMHS) Research Group. JAMA; 275:1549-56.
3. BMJ (1999); 319: 630-5.
4. Kostis JB et al (2005). Long-term effect of diuretic-based therapy on fatal outcomes in subjects with isolated systolic hypertension with and without diabetes. Am J Cardiol; 95:29-35.
5. NICE (August 2019). Clinical management of hypertension in adults.