A dose of long-acting diltiazem at bedtime is more effective than a morning dose of amlodipine in reducing high blood pressure in black patients, new study findings suggest. The drug works best at reducing blood pressure in the morning - the time of day when heart attacks and strokes are most likely to occur.

The study was sponsored by Biovail Pharmaceuticals, which markets long-acting diltiazem under the name Cardizem, L.A.

The study, which is reported in the American Journal of Hypertension, involved 262 African Americans with high blood pressure who were randomly selected to receive Cardizem at nighttime or amlodipine in the morning for 6 weeks. Blood pressure and heart rate were measured continuously throughout the day.

Cardizem was more effective than amlodipine at reducing heart rate in the morning as well over 24 hours, lead author Dr. Jackson T. Wright, from Case Western Reserve University in Cleveland, and colleagues note.

Both drugs provided comparable reductions in 24-hour diastolic blood pressure (the lower number on a blood pressure reading), but Cardizem was better at reducing morning diastolic blood pressure.

In contrast, amlodipine provided greater reductions in 24-hour systolic blood pressure (the higher number on a blood pressure reading) than Cardizem.

Both agents were well tolerated and no unexpected or severe side effects were observed with either, the investigators state.

The reductions in blood pressure and heart rate achieved with Cardizem, especially during the early morning hours, “may provide advantages to patients at risk” for heart attacks and stroke, the authors conclude.

SOURCE: American Journal of Hypertension, September 2004.