Doxazosin GITS versus hydrochlorothiazide as add-on therapy in patients with uncontrolled hypertension

The objective of this prospective, randomized, open-label, parallel-arm comparative study, with a 4-month follow-up, was to assess the antihypertensive efficacy, tolerability and metabolic safety of doxazosin GITS (gastrointestinal therapeutic system) 4-8 mg/day vs hydrochlorothiazide (HCTZ) 12.5-25 mg/day as add-on therapy in patients not controlled with monotherapy with other drugs. Ninety-eight patients completed the study (mean age 57.4 +/- 15 years, 53% female). Mean systolic/diastolic blood pressure reduction was 8.2/4.5 mmHg in the HCTZ group and 8.9/5.0 mmHg in the doxazosin GITS group, and a strict blood pressure control was achieved in 79% and 83% of the patients, respectively. The incidence rates of adverse events were low and similar in both groups. However, metabolic differences were seen between the groups, doxazosin GITS vs HCTZ, respectively: total cholesterol (mg/dl) 210 +/- 53 vs 231 +/- 62 (p < 0.05), low-density lipoprotein (LDL) cholesterol (mg/dl) 139 +/- 40 vs 161 +/- 57 (p < 0.01), high-density lipoprotein (HDL) cholesterol (mg/dl) 58 +/- 16 vs 48 +/- 13 (p < 0.01), HDL/total cholesterol ratio 27.6 +/- 8 vs 21.2 +/- 7 (p < 0.001), plasma uric acid (mg/dl) 5.3 +/- 2.6 vs 6.8 +/- 3.1 (p < 0.05) and serum potassium (mEq/l) 4.1 +/- 1.3 vs. 3.7 +/- 1.2 (p < 0.01). In conclusion, doxazosin GITS has a tolerability and efficacy profile similar to low doses of thiazide diuretics, with a better evolution of metabolic and electrolyte parameters. Therefore, in patients not controlled with monotherapy, doxazosin GITS can be considered an alternative to the addition of thiazide diuretics.