In our area of care, hydrochlorothiazide (HCT) is dispensed as thiazide diuretic. Can the results from chlorthalidone (a-t 2003; 34: 1-2) now simply be applied to HCT?

J. HOLSTEN (pharmacist, Central Hospital St.-Jürgen-Str.)
D-28205 Bremen
Conflict of interests: none

Taking into consideration both the results from the ALLHAT* study (1) and the other long-term studies to date on anti-hypertensive therapy, then best evidence of a clinical benefit is provided for chlorthalidone (HYGROTON) and thiazide diuretics. Chlorthalidone and hydrochlorothiazide (ESIDRIX etc.) were the main agents investigated in studies testing low-dose diuretics, which according to a meta-analysis protected better against sequelae of high blood pressure than diuretics given in high dosage (e.g. 50 mg hydrochlorothiazide initially) (2). Therefore from our point of view not only low-dose chlorthalidone but also low-dose thiazide diuretics, in particular hydrochlorothiazide, should be preferred for first-step anti-hypertensive therapy.

In the ALLHAT* and SHEP** study (3) on chlorthalidone the starting dose was 12.5 mg per day. If this dose was not adequately efficacious, the dosage was doubled to 25 mg daily. There are no corresponding outcome studies on hydrochlorothiazide for this low-dose strategy with an initial dose of 12.5 mg. The low-dose scheme investigated in studies with clinical endpoints on hydrochlorothiazide always had a starting dose of 25 mg per day (4-10). However taking into account the strong response to its blood pressure-lowering and diuretic property, particularly in old people, it appears to us that an initial daily dose of 12.5 mg should be recommended in the case of hydrochlorothiazide, too. -ed.

(R = randomised study, M = meta-analysis)

1

ALLHAT Officers and Coordinators: JAMA 2002; 288: 2981-97

2

PSATY, B.M. et al.: JAMA 1997; 277: 739-45

3

SHEP Cooperative Research Group: JAMA 1991; 265: 3255-64

4

AMERY, A. et al.: Lancet 1985; 1: 1349-54

5

DAHLÖF, B. et al.: Lancet 1991; 338: 1281-5

6

Medical Research Council Working Party: BMJ 1992; 304: 405-12

7

BORHANI, N.O. et al.: JAMA 1996; 276: 785-91

8

BROWN, M.J. et al.: Lancet 2000; 356: 366-72

9

HANSSON, L. et al.: Lancet 1999; 353: 611-6

10

HANSSON, L. et al.: Lancet 1999; 354: 1751-6

ALLHAT = Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (a-t 2003; 34: 1-2)

SHEP = Systolic Hypertension in the Eiderly Program