How is hydrochlorothiazide (HCTZ) usually taken?

The usual initial antihypertensive dose of hydrochlorothiazide (HCTZ) in adults is 25 mg daily given as a single oral pill dose.¹ The dose may be increased to 50 mg daily, given as one dose or two divided doses.

Diuresis from HCTZ begins within two hours of oral dose.^1-4 HCTZ reaches maximum bioavailability in four to six hours.^1-3 Elimination half-life ranges from about 8 to 15 hours with long-term dosing.^1,2,5

^References

1. Hydrochlorothiazide [package insert]. Morgantown, WV: Mylan Pharmaceuticals, Inc.; 2011.
2. Carter BL, Ernst ME, Cohen JD. Hydrochlorothiazide versus chlorthalidone: Evidence supporting their interchangeability. Hypertension 2004; 43 (1): 4-9.
3. Giudicelli JF, Richer C, Mattei A. Pharmacokinetics and biological effects of captopril and hydrochlorothiazide after acute and chronic administration either alone or in combination in hypertensive patients. Br J Clin Pharmacol 1987; 23 Suppl 1: 51s-63s.
4. Jordo L, Johnsson G, Lundborg P, Persson BA, Regardh CG, Ronn O. Bioavailability and disposition of metoprolol and hydrochlorothiazide combined in one tablet and of separate doses of hydrochlorothiazide. Br J Clin Pharmacol 1979; 7 (6): 563-567.
5. Ernst ME, Carter BL, Zheng S, Grimm RH, Jr. Meta-analysis of dose-response characteristics of hydrochlorothiazide and chlorthalidone: Effects on systolic blood pressure and potassium. Am J Hypertens 2010; 23 (4): 440-446.