Effectiveness of hydrochlorothiazide in combination with telmisartan and olmesartan in adults with moderate hypertension not controlled with monotherapy: A prospective, randomized, open-label, blinded end point (PROBE), parallel-arm study

BACKGROUND: The potential combinations of antihypertensive agents are many, and making rational choices depends on the characteristics of each drug and on their complementary mechanisms of action. OBJECTIVE: The aim of this study was to evaluate the effectiveness of adding hydrochlorothiazide (HCTZ) 12.5 mg to olmesartan 20 mg or telmisartan 80 mg on blood pressure (BP) in patients with moderate hypertension. METHODS: Consecutive outpatients at the Centro per l'Ipertensione e la Fislopatologia Cardiovascolare, University of Pavia, Pavia, Italy, of both sexes aged 39 to 75 years were considered eligible for enrollment if they had a sitting diastolic BP (DBP) >= 99 mm Hg and <110 mm Hg at the end of an initial 2-week washout period. Patients were randomized to olmesartan 20 mg QD or telmisartan 80 mg QD according to a prospective, open-label, blinded end point, parallel-arm design. After 8 weeks of monotherapy, patients whose BP was not controlled (DBP >= 90 mm Hg) received HCTZ 12.5 mg QD for 8 additional weeks. Clinical and ambulatory BPs were measured at the end of the washout period and at the end of both treatment periods. Adverse events (AEs) were recorded from spontaneous reports and direct inquiry from investigators. RESULTS: One hundred forty-five patients, all of whom were white, were recruited for the study. After the initial washout period, 13 patients did not meet the inclusion criteria and 6 refused to continue. A total of 126 white patients (69 men, 57 women; mean [SD] age, 60.2 [11.6] years) were randomized to receive monotherapy. Of these, 35 patients (56%) in the olmesartan group and 33 (52%) in the telmisartan group had previously received anti hypertensive therapy. At the end of monotherapy, the 52 patients in the olmesartan group and the 49 patients in the telmisartan treatment group who were still in the study and had their BP inadequately controlled by treatment had HCTZ 12.5 mg QD added to their treatment regimen. Both combinations induced a greater ambulatory mean (SD) systolic BP (SBP) and DBP reduction than monotherapy (SBP: 145.3 [6.1] in the olmesartan group and 140.1 [6.4] in the telmisartan group, P < 0.05; DBP: 88.1 [5.1] in the olmesartan group and 849 [49] in the telmisartan group, P < 0.05). The mean (SD) reduction from baseline in the tetmisartan/HCTZ-treated patients (21.5 [10.1]/14.6 [5.2] mm Hg for 24 hours, 21.8 [10.2]/14.9 [5.2] mm Hg for daytime, and 20.4 [10.3]/13.7 [59] mm Hg for nighttime; all, P < 0.001 vs baseline) was significantly greater than that observed in the olmesartan/HCTZ-treated patients (18.8 [9.8]/12.3 [4.9] mm Hg for 24 hours, 19.3 [9.8]/12.8 [49] mm Hg for daytime, and 17.4 [10.2]/10.6 [5.5] mm Hg for nighttime; all, P < 0.001 vs baseline), with a significant difference between the 2 treatment groups (P < 0.01). Compared with monotherapy, the add-on effect of HCTZ 12.5 mg QD administration was significantly greater in the telmisartan group than in the olmesartan group (P < 0.05); the difference being more evident for nighttime BP values (SBP, P = 0.031; DBP, P = 0.025). Reported AEs were similar in the olmesartan/HCTZ and the telmisartan/HCTZ groups (4 patients [7%] vs 3 patients [6%]). CONCLUSION: The addition of HCTZ 12.5 mg to telmisartan 80 mg monotherapy was associated with greater BP reduction than the addition of the same dose of HCTZ to olmesartan 20 mg monotherapy in these patients previously uncontrolled on monotherapy.