Trough:peak ratio of nifedipine gastrointestinal therapeutic system and nifedipine retard in essential hypertensive patients: an Italian multicentre study

Combination of lisinopril and nifedipine GITS increases blood pressure control compared with single drugs in essential hypertensive patients

The present study was designed to evaluate the effect of combination therapy using the angiotensin-converting enzyme-inhibitor lisinopril and the dihydropyridine calcium antagonist nifedipine GITS on the degree and homogeneity of 24-hour blood pressure reduction in essential hypertensive patients. After a 4-week placebo run-in period, 51 patients (mean age, 54.4 +/- 9.4 years) with essential hypertension and clinic diastolic blood pressure between 105 and 115 mm Hg were randomized to 4-week treatment with lisinopril (20 mg), nifedipine GITS (30 mg), or their combination according to a multicenter, randomized, double-blind, crossover study. Trough clinic blood pressure and 24-hour ambulatory blood pressure were measured at the end of the run-in period and after 4 weeks of treatment. In addition to clinic and 24-hour average blood pressure reduction, the trough-to-peak ratio and the smoothness index, a new measure for the homogeneity of blood pressure reduction, were also calculated. Although both lisinopril and nifedipine GITS produced a significant reduction in clinic and 24-hour average blood pressure values, the reduction obtained with the combination was significantly (P < 0.001) greater. Moreover, the combination therapy increased (P < 0.01) the smoothness index as compared with each single drug for both systolic (lisinopril, 1.02; nifedipine GITS, 1.1; combination, 1.76) and diastolic (lisinopril, 0.98; nifedipine GITS, 0.87; combination, 1.54) blood pressure values, whereas trough-to-peak ratio values (expressed as median) for systolic (lisinopril, 0.41; nifedipine GITS, 0.52; combination, 0.55) and diastolic (lisinopril, 0.35; nifedipine GITS, 0.40; combination, 0.49) blood pressure values were not significantly increased by the combination therapy. Thus, antihypertensive treatment with the combination of lisinopril and nifedipine GITS is more effective and balanced over the 24 hours than the combination components administered alone, confirming that the smoothness index is superior to the trough-to-peak ratio in assessing homogeneity of pharmacologic blood pressure reduction.