EFFECT OF ACUTE AND LONG-TERM ADMINISTRATION OF RAMIPRIL ON CIRCADIAN-RHYTHM OF BLOOD-PRESSURE IN ESSENTIAL-HYPERTENSION

Ambulatory monitoring was used to evaluate the antihypertensive efficacy and effect on circadian rhythms of blood pressure and heart rate of a single dose and long-term administration of ramipril in 20 patients with mild to moderate essential hypertension. Patients initially were randomized to receive either placebo or a single 5-mg dose of ramipril, followed 1 week later by 5 mg of ramipril daily for 6 months. Systolic (SBP) and diastolic blood pressure (DBP) and heart rate were measured every 20 minutes for 24 hours. Single-dose ramipril reduced both SBP and DBP (P<.001) without affecting heart rate. Long-term treatment produced a small additional antihypertensive effect, again without modifying heart rate. Cosinor analysis demonstrated that both administrations of ramipril effectively lowered SBP and DBP mesors (P<.001), compared to placebo; circadian rhythms remained undisturbed. Heart rate also was not modified on any circadian parameter. A significant reduction (P<.001) of blood pressure amplitude, however, occurred after long-term treatment and may have importance in terms of preventing cardiac damage.