24-hour blood pressure control by once-daily administration of irbesartan assessed by ambulatory blood pressure monitoring. Irbesartan Multicenter Investigators' Group

OBJECTIVES: To compare 24 h ambulatory blood pressure and trough office blood pressure lowerings after 8 weeks of therapy with 75 mg irbesartan once a day, 150 mg irbesartan once a day , and 75 mg irbesartan twice a day versus placebo; and to assess safety and tolerability of irbesartan therapy.

DESIGN: Multicenter, double-blind, randomized, placebo-controlled trial.

SETTING: Sixteen centers in Italy.

PATIENTS: Caucasian patients (n = 215) aged > or = 18 years with seated diastolic blood pressure 95-110 mmHg and ambulatory diastolic blood pressure (ADBP) > or = 85 mmHg.

PRIMARY OUTCOME: Mean 24 h ADBP after 8 weeks of irbesartan therapy.

RESULTS: Mean changes (value before treatment minus value after treatment) in ADBP for placebo, 75 mg irbesartan once a day, 150 mg irbesartan once a day, and 75 mg irbesartan twice a day were -0.2, -5.4, -7.2, and -7.2 mmHg, respectively; respective changes in ambulatory systolic blood pressure were +1.6, -8.3, -10.5, and -9.7 mmHg. All irbesartan regimens reduced trough office seated diastolic blood pressure and seated systolic blood pressure after 2 and 8 weeks of treatment (all P < 0.01, versus placebo except for seated systolic blood pressure in patients in the 75 mg irbesartan once a day group). Trough: peak ratios were > or = 55% with 150 mg irbesartan once a day. Percentages of patients whose blood pressures were normalized with 150 mg irbesartan once a day (45%) and 75 mg irbesartan twice a day (47%) were greater than those with placebo (14%, P < 0.01) and with 75 mg irbesartan once a day (19%, NS, versus placebo). Adverse events with irbesartan were similar to those with placebo.

CONCLUSIONS: All irbesartan regimens significantly reduced mean 24 h ADBP and ambulatory systolic blood pressure, and were well tolerated. Administration of 150 mg irbesartan once a day provided significant reduction of blood pressure for 24 h, equivalent to that obtained with the same daily dose divided into two separate administrations