ABSTRACT
To study the antihypertensive effect of dihydropyridines and correlated with the patient's age, the degree of hypertension and mean arterial pressure, in three groups of eight hypertensive patients with mild, moderate and severe hypertension selected from the Clinical Pharmacology Unit of Vargas Hospital in Caracas. Mean age, weight and height of the selected patients were 55.66 ¤ 3.4, years 67 ¤ 3.05 Kg and 1.63 ¤ 0.01 m, respectively. Three acute experimental designs compared with placebo were followed and each group of patients received amlodipine, nitrendipine or isradipine at different times, in single doses of 10,20 and 5 mg, respectively. The cardiovacular parameters evaluated were: mean arterial pressure, systolic blood pressure, diastolic blood pressure and cardiac frequency at regular intervals during 48,6 and 24 hours for amlodipine, nitrendipine and isradipine, respectively. Acute administration of amlodipine (10 mg) to hypertensive patients, significantly reduced blood pressure form 185 ¤ 11.21/100 ¤ 7.07 to 150.5 ¤ 10.6/88.6 ¤ 7.8 mmHg at 8 hours and to 162 ¤ 10.9/91 ¤ 5.6 mmHg at 48 hour. Cardiac frequency also increased significantly at 8 and 48 hours in 10 and 9 beats/min, respectively. There was a positive correlation between patient's age and mean arterial pressure decrease and also between pretreatment and decreased arterial pressure. Two hours after acute administration of isradipine (5 mg) to hypertensive patients, blood pressure decreased significantly from 179.50 ¤ 7.6/100.26 ¤ 3.28 mmHg to 143.75 ¤ 4.7/82 ¤ 5.18 mmHg. Cardiac frequency increased in 5 beats/min at the same time of measure. There was a positive correlation between patient's age and arterial pressure decrease and slight but not significant correlation between pretreatment and mean arterial blood pressure decrease. Acute dose of nitrendipine (20 mg) to hypertensive patients induced significant fall of arterial blood pressure from 172.25 ¤ 7.8/107.13 ¤ 3,58 to 134.5 ¤ 5.08/81 ¤ 5.84 mmHg two hours after the administration of the drug, and the cardiac frequency increased significantly in 11 beats/min during this time. There was no significant correlation between patient's age and the mean arteral pressure fall, neither between pretreatment and the decrease of arterial blood pressure