Purpose: To evaluate clinical efficacy and tolerability of isradipine SRO (I.SRO), 5 mg O.D. in essential hypertensives.
Methods: Eighty-three of 87 selected outpatients with a mean age of 51.3 years (ranging from 25 to 65), 33 male, 48 white, 29 black and others of different races, who had clinical supine and orthostatic diastolic blood pressure (DBP) > or = 95 mmHg and < or = 115 mmHg underwent the study. After a three-week wash-out period, patients received I.SRO 5 mg O.D. at 8:00 am for a six-week period (phase I). After this phase, patients received I.SRO 5 mg O.D. at 8:00 pm for a six-week period (phase II). The patients had a follow-up with an interval of three weeks and the ambulatorial blood pressure monitoring (ABPM) for 24 hours was performed with a SpaceLabs 90207 or Del Mar Avionics devices after the wash-out period and at the end of phases I and II. Measurements were performed at 15-min intervals during the day (6 am to 10 pm) and at 30-min intervals during the night (10 pm to 6 am).
Results: a) Heart rate did not show significant changes during the treatment period (phases I and II) when compared with the wash-out period; b) causal blood pressure: at the end of both treatment periods (phases I and II) there were statistically significant decreases (p < 0.001) in supine SBP and DBP compared with wash-out values. The mean SBP decreased from 161.6 +/- 14 to 144.3 +/- 13 mmHg (phase I) and to 141.8 +/- 13 mmHg (phase II). The mean DBP decreased from 103.4 +/- 6 to 91.2 +/- 7 (phase I) and to 89.1 +/- 8 (phase II); c) ABPM: the mean systolic 24-h ambulatory blood pressure was significantly reduced (p < 0.001) from 148.8 +/- 17 to 137.2 +/- 15 mmHg (phase I) and to 133.4 +/- 13 mmHg (phase II). The mean diastolic 24-h ambulatory blood pressure was significantly decreased (p < 0.001) from 94.3 +/- 9 to 87.0 +/- 9 (phase I) and to 85.8 +/- 8 mmHg (phase II). The mean daytime and nighttime, systolic and diastolic 24-h ambulatory blood pressure were: wash-out--152.3 +/- 17, 140.2 +/- 21, 97.4 +/- 9, 86.8 +/- 13; phase I--139.9 +/- 15, 130.0 +/- 17, 89.3 +/- 9, 81.3 +/- 10; phase II--136.7 +/- 13, 125.3 +/- 15, 88.5 +/- 8, 79.1 +/- 10, respectively. Blood pressure load (percentage of systolic blood pressure values > 140 mmHg or of diastolic blood pressure values > 90 mmHg) was significantly reduced from 62.2/62% (SBP/DBP), on the was-out, to 37.9/39.9% (SBP/DBP) on phase I and to 32.3/34.3% (SBP/DBP) on phase II; d) side effects: most frequently related were palpitations (2.3%), headache (1.1%), flush (1%) and ankle oedema (1%). They were in general, mild-to-moderate and disappeared after the first 3 weeks of treatment. Only two patients were withdrawn because of headache (one of them with previous diagnosis of migraine).
Conclusion: I.SRO, given by oral route, in the dosage of 5 mg O.D. as monotherapy, was effective and well tolerated, promoted significant reduction on 24-h ambulatory blood pressure attenuating the early morning rise and did not interfere with the circadian rhythm of blood pressure. No significant differences were detected in the BP lowering effect when I.SRO was given during the morning or evening. These results may indicate that the drug is as suitable as one of the first choice for treating mild and moderate hypertensive patients.