I-COMBINE study: assessment of efficacy and safety profile of irbesartan/amlodipine fixed-dose combination therapy compared with amlodipine monotherapy in hypertensive patients uncontrolled with amlodipine 5 mg monotherapy: a multicenter, phase III, prospective, randomized, open-label with blinded-end point evaluation study.

BACKGROUND: Hypertension guidelines recommend the use of 2 agents with synergistic action when >1 agent is needed to achieve blood pressure goals. Newer antihypertensive treatment combinations include fixed-dose combinations of an angiotensin receptor blocker and a calcium channel blocker.

OBJECTIVE: The I-COMBINE study aimed to determine whether the antihypertensive efficacy of the fixed-dose combination irbesartan 150 mg/amlodipine 5 mg (I150/A5) was superior to that of amlodipine 5 mg (A5) monotherapy in lowering home systolic blood pressure (HSBP) after 5 weeks' treatment.

METHODS: The I-COMBINE study was a 10-week, multicenter, Phase III, prospective, randomized, parallel-group, open-label with blinded-endpoint study. The main inclusion criterion was essential uncontrolled hypertension (SBP ≥145 mm Hg at office, after at least 4 weeks of A5 monotherapy administered once daily). Patients continued to receive A5 for 7 to 10 days and were randomized to either monotherapy with A5 for 5 weeks then amlodipine 10 mg (A10) for the next 5 weeks or to a fixed-dose combination therapy (I150/A5 then I150/A10). Safety profile was assessed by recording adverse events reported by patients or observed by the investigator.

RESULTS: Following enrollment, 290 patients were randomized to treatment, and 287 (mean [SD] age, 57.3 [11.2] years; 48% male) were included in the intention-to-treat analysis: 144 patients treated with I150/A5 then I150/A10, and 143 patients treated with A5 then A10. At randomization, mean HSBP was similar in both groups: 148.5 (10.3) mm Hg in the I150/A5 group and 149.2 (9.7) mm Hg in the A5 group. At week 5, the adjusted mean difference in HSBP between groups was -6.2 (1.0) mm Hg (P < 0.001). The proportion of controlled patients (mean home blood pressure <135 and 85 mm Hg) was significantly higher in the I150/A5 group than in the A5 group (P < 0.001). Treatment-emergent adverse events were experienced by 13.8% of I150/A5-treated patients and 11.9% of A5-treated patients during the first 5-week period, and by 15.8% of I150/A10-treated patients and 17.0% of A10-treated patients during the second 5-week period. Two serious adverse events were reported with the fixed-dose combination; both patients recovered.

CONCLUSIONS: Data from this adult population with essential hypertension suggest greater efficacy with the fixed-dose combination I150/A5 over A5 monotherapy in lowering SBP after 5 weeks. Both treatment regimens were well tolerated throughout the study. ClinicalTrials.gov identifier: NCT00956644.