[Circadian rhythm of arterial pressure and use of amlodipine in primary hypertension].

PURPOSE: To evaluate the anti hypertensive efficacy and tolerability of amlodipine given once daily either morning and evening doses.

METHODS

Fifty hypertensive patients were admitted into an open non comparative 18 weeks study. All patients were submitted to wash out period of 2 weeks. Afterwards, those with BP inclusion criteria started 5 mg amlodipine, which was titrated until a maximum of 10 mg. Upon reaching the ideal dosage, patients were kept 8 weeks with drug given at 8:00 am and then 8:00 pm.

RESULTS

The majority of patients (60%) needed only 5 mg and 24 hours data revealed the following mean systolic BP: V2 (final of wash-out) = 149.3 +/- 4.8; V3 (morning dose) = 150.4 +/- 3.8; V4 (night dose) = 134.1 +/- 2.9; V5 (final of the study) = 129.5 +/- 6.1 (ANOVA p = 0.000; Bonferroni test: p < 0.05; test t of Student: p = 0.13, comparing V2 (final of wash-out) with V4 (night dose) and V5 (final of study). The mean diastolic BP were V2 (final of wash-out) = 96 +/- 3.2 (morning dose) = 96.2 +/- 2.7; V4 (night dose) = 81.9 +/- 2.6; V5 (final of the study) = 77.7 +/- 7.5 (ANOVA: p = 0.000; Bonferroni test: p = < 0.05; test t: p = 0.05). The following systolic percentage over normal values were observed (140 mmHg from 7:00 am to 11:00 pm; 130 mmHg from midnight to 7:00 am): V2 (final of wash-out) = 73.3% during the day and 71.1% at night; V3 (morning dose) = 76% in the morning and 75.6% at night; V4 (night dose) = 29.3% during the day and 39.3% at night; 20.9% during the day and 23% at night. Considering the limits of diurnal diastolic BP 90 mmHg and nocturnal, 80 mmHg, the following percentage of readings over normal limits were observed: V2 (final of wash-out) = 77.8% during the day and 91.8% at night; V3 (morning dose) = 80% during the day and 92.6% at night; V4 (night dose) = 6.7% during the day and 15.6% at night. Three patients presented adverse events, which disappeared spontaneously and discontinuation of treatment was not necessary.

CONCLUSION

Amlodipine was considered effective and well tolerated and the majority of patients needed only 5mg daily and no reflex tachycardia was observed. Amlodipine effectively reduced BP throughout 24 h and the circadian rhythm kept unaltered and the evening administration led to a greater nocturnal fall than the morning administration. The remaining periods did not show differences.