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.